What is the most common food allergies

A food allergy occurs when the body’s immune system sees a certain food as harmful and reacts by causing symptoms. This is an allergic reaction. Foods that cause allergic reactions are allergens.

IgE Mediated Food Allergies

The IgE mediated food allergies most common in infants and children are eggs, milk, peanuts, tree nuts, soy and wheat.

The allergic reaction can involve the skin, mouth, eyes, lungs, heart, gut and brain. Some of the symptoms can include:

  1. Skin rash, itching, hives
  2. Stomach pain, vomiting, diarrhea
  3. Shortness of breath, trouble breathing, wheezing
  4. Feeling love something terrible is about to happen
  5. Swelling of the lips, tongue or throat
  6. Immunoglobulin E (IgE) mediated. Symptoms result from the body’s immune system making antibodies called Immunoglobulin E (IgE) antibodies.

    These IgE antibodies react with a certain food.

  7. Non-IgE mediated. Other parts of the body’s immune system react to a certain food. This reaction causes symptoms, but does not involve an IgE antibody. Someone can own both IgE mediated and non-IgE mediated food allergies.

Sometimes allergy symptoms are mild. Other times they can be severe. Take every allergic symptoms seriously. Mild and severe symptoms can lead to a serious allergic reaction called anaphylaxis (anna-fih-LACK-sis). This reaction generally involves more than one part of the body and can get worse quick. Anaphylaxis must be treated correct away to provide the best chance for improvement and prevent serious, potentially life-threatening complications.

Treat anaphylaxis with epinephrine.

This medicine is safe and comes in an easy-to-use device called an auto-injector. You can’t rely on antihistamines to treat anaphylaxis. The symptoms of an anaphylactic reaction happen shortly after contact with an allergen. In some individuals, there may be a delay of two to three hours before symptoms first appear.

Cross-Reactivity and Oral Allergy Syndrome

Having an IgE mediated allergy to one food can mean your kid is allergic to similar foods. For example, if your kid is allergic to shrimp, he or she may be allergic to other types of shellfish, such as crab or crayfish. Or if your kid is allergic to cow’s milk, he or she may also be allergic to goat’s and sheep’s milk.

The reaction between diverse foods is called cross-reactivity. This happens when proteins in one food are similar to the proteins in another food.

Cross-reactivity also can happen between latex and certain foods. For example, a kid who has an allergy to latex may also own an allergy to bananas, avocados, kiwis or chestnuts.

Some people who own allergies to pollens, such as ragweed and grasses, may also be allergic to some foods. Proteins in the pollens are love the proteins in some fruits and vegetables. So, if your kid is allergic to ragweed, he or she may own an allergic reaction to melons and bananas.

That’s because the protein in ragweed looks love the proteins in melons and bananas. This condition is oral allergy syndrome.

Symptoms of an oral allergy syndrome include an itchy mouth, throat or tongue. Symptoms can be more severe and may include hives, shortness of breath and vomiting. Reactions generally happen only when someone eats raw food. In rare cases, reactions can be life-threatening and need epinephrine.

Two Categories of Food Allergies

  • Immunoglobulin E (IgE) mediated. Symptoms result from the body’s immune system making antibodies called Immunoglobulin E (IgE) antibodies. These IgE antibodies react with a certain food.
  • Non-IgE mediated. Other parts of the body’s immune system react to a certain food.

    This reaction causes symptoms, but does not involve an IgE antibody. Someone can own both IgE mediated and non-IgE mediated food allergies.

Non-IgE Mediated Food Allergies

Most symptoms of non-IgE mediated food allergies involve the digestive tract. Symptoms may be vomiting and diarrhea. The symptoms can take longer to develop and may final longer than IgE mediated allergy symptoms. Sometimes, a reaction to a food allergen occurs up 3 days after eating the food allergen.

When an allergic reaction occurs with this type of allergy, epinephrine is generally not needed.

In general, the best way to treat these allergies is to stay away from the food that causes the reaction. Under are examples of conditions related to non-IgE mediated food allergies.

Not every children who react to a certain food own an allergy. They may own food intolerance. Examples are lactose intolerance, gluten intolerance, sulfite sensitivity or dye sensitivity. Staying away from these foods is the best way to avoid a reaction. Your child’s doctor may propose other steps to prevent a reaction. If your kid has any food allergy symptoms, see your child’s doctor or allergist. Only a doctor can properly diagnose whether your kid has an IgE- or non-IgE food allergy.

Both can be present in some children.

Eosinophilic Esophagitis (EoE)

Eosinophilic (ee-uh-sin-uh-fil-ik) esophagitis is an inflamed esophagus. The esophagus is a tube from the throat to the stomach. An allergy to a food can cause this condition.

With EoE, swallowing food can be hard and painful. Symptoms in infants and toddlers are irritability, problems with eating and poor weight acquire. Older children may own reflux, vomiting, stomach pain, chest pain and a feeling love food is “stuck” in their throat. The symptoms can happen days or even weeks after eating a food allergen.

EoE is treated by special diets that remove the foods that are causing the condition.

Medication may also be used to reduce inflammation.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

FPIES is another type of food allergy. It most often affects young infants. Symptoms generally don’t appear for two or more hours. Symptoms include vomiting, which starts about 2 hours or later after eating the food causing the condition. This condition can also cause diarrhea and failure to acquire weight or height. Once the baby stops eating the food causing the allergy, the symptoms go away.

Rarely, severe vomiting and diarrhea can happen which can lead to dehydration and even shock. Shock occurs when the body is not getting enough blood flow. Emergency treatment for severe symptoms must happen correct away at a hospital. The foods most likely to cause a reaction are dairy, soy, rice, oat, barley, green beans, peas, sweet potatoes, squash and poultry.

Allergic Proctocolitis

Allergic proctocolitis is an allergy to formula or breast milk.

This condition inflames the lower part of the intestine. It affects infants in their first year of life and generally ends by age 1 year.

The symptoms include blood-streaked, watery and mucus-filled stools. Infants may also develop green stools, diarrhea, vomiting, anemia (low blood count) and fussiness. When properly diagnosed, symptoms resolve once the offending food(s) are removed from the diet.

Medical review December

For Immediate Release Contact: Jo Ann Faber at () [email protected]

ARLINGTON HEIGHTS, Ill., July 24, Food allergy knowledge in the general public is poor concerning the difference between food allergy and food intolerance, the absence of a cure, and current treatments according to a report published this month in Annals of Allergy, Asthma & Immunology, the scientific journal of the American College of Allergy, Asthma and Immunology (ACAAI).

"The public s food allergy knowledge and awareness is critical to the safety of children with food allergy, especially since 76 percent of food allergy-related deaths follow consumption of foods exterior of the home.

Food allergy is a growing health concern, affecting an estimated 6 percent to 8 percent of children in the United States," said Ruchi S. Gupta, M.D., of the Mary Ann & J. Wilburn Smith Children Health Research Program at Children s Memorial Research Middle in Chicago.

In a national sample of 2, adults who completed the validated Web-based Chicago Food Allergy Research Survey for the General Public, Dr. Gupta and colleagues found "the public s knowledge was strongest regarding symptoms and severity of food allergy, with almost 95 percent of participants recognizing food allergy as a potentially fatal condition."

Among the misconceptions, investigators reported that "almost half of participants erroneously believed that a cure exists for food allergy, and more than two thirds stated that a daily medicine could be taken to prevent a food allergy reaction.

They also tended to overlook the necessity of strict allergen avoidance: more than 40 percent of participants indicated that other means exist to prevent life-threatening reactions."

Authors noted that almost 85 percent of respondents agreed that schools should own plans to hold food-allergic children safe.

"Although there was agreement that schools need better policies to manage food allergies, most parents were not in favor of implementation of specific school policies, such as banning peanut products and having special tables for food-allergic children," Dr.

Gupta said.

Investigators conclude that "increased food allergy knowledge among the general public is needed, especially regarding the distinction between food allergy and food intolerance, current treatments available for food allergy, the absence of a cure, and the lack of preventative medications."

"Although food allergy is a commonplace term, this study confirms the prevailing misconceptions among the public regarding manifestations, diagnosis, and treatment," said Sami L.

Bahna, M.D., Dr.P.H., professor of pediatrics & medicine, chief of Allergy & Immunology Section at Louisiana State University Health Sciences Middle in Shreveport, La., and president-elect of ACAAI. "Appropriate diagnosis is the cornerstone for appropriate management. Also, exclusion of food allergy would direct the search to other causes of the patient s illness. At present the treatment is basically strict avoidance of the causative foods. Research is underway for effective and safe immunotherapy."

To the author s knowledge, "this study is the first to provide detailed information about the general public s food allergy knowledge and to characterize the general public s attitudes and beliefs toward food allergy and food allergy policy."

About Food Allergy

Current treatment of food allergy includes identification and strict avoidance of the offending food, and recognition of systems that can lead to anaphylaxis.

Anaphylaxis is the most severe form of allergic reactions, affecting multiple organ systems. Symptoms can include chest tightness, wheezing, nausea, vomiting, cramping, hives, and swelling of the lips and joints. The most dangerous symptoms are breathing difficulties, throat swelling, chest wheezing, dizziness, low blood pressure, shock and loss of consciousness, every of which can be fatal. Patients with severe reactions should own continued access to self-istered epinephrine injections.

The most common food allergens in infants and young children are cow s milk, hen s egg, peanut (a legume), tree nuts (walnut, hazelnut, Brazil nut, and pecan), soybeans and wheat.

Although sensitivity to most allergens is lost in tardy childhood, allergy to peanut, tree nut and seafood is likely to continue throughout the patient s life. Only approximately 20 percent of children with peanut allergy lose their sensitivity. The most common foods causing allergy in adults are peanuts, tree nuts, fish, crustaceans, mollusks, fruits and vegetables.

Patient information on allergic diseases including food allergy is available by visiting the ACAAI Web site at

About ACAAI

The American College of Allergy, Asthma and Immunology (ACAAI) is a professional medical organization headquartered in Arlington Heights, Ill., that promotes excellence in the practice of the subspecialty of allergy and immunology.

The College, comprising more than 5, allergists-immunologists and related health care professionals, fosters a culture of collaboration and congeniality in which its members work together and with others toward the common goals of patient care, education, advocacy and research.

###

Citation: Gupta RS,et al. Food allergy knowledge, attitudes, and beliefs in the United States. Ann Allergy Asthma Immunol ;

Annals of Allergy, Asthma & Immunology is online at

Centuries ago, Lucretius said that one man’s food may be another man’s poison.

What is the most common food allergies

Such is the case with food allergies. Individuals with food allergies and other types of food sensitivities react adversely to the ingestion of foods and food ingredients that most consumers can ingest with no problems.

Eating is necessary to sustain life. For most consumers, eating is an enjoyable experience given the variety and abundance of foods available in the marketplace. For some individuals, however, consuming certain foods can be a debilitating, possibly even life-threatening, experience.

Individuals with various forms of food allergies and sensitivities must avoid certain foods or food ingredients in their diets. For such people, the joy of eating is diminished by the ever-present concern that they might consume a food or food ingredient that will elicit an adverse reaction. For them, food selection can become a tedious task requiring the painstaking reading of ingredient lists on the labels of packaged foods and a ceaseless search for more knowledge about food composition. Food preparation requires careful attention to details such as “cooking from scratch,” seeking alternative recipes for numerous dishes, and avoidance of shared utensils, containers, and cooking surfaces between allergenic and non-allergenic foods.

In situations where one family member has a extremely serious allergic sensitivity, the entire family often has to avoid the offending food as a precautionary measure.

Definitions
Food allergies and other food sensitivities are individualistic adverse reactions to foods (Taylor, ). These food-related illnesses are individualistic because they affect only a few people in the population; most consumers can eat the same foods with no ill effects.

Numerous diverse types of reactions are involved in these individualistic adverse reactions to foods (Fig. 1; Anderson, ; Taylor, ). Adverse food reactions can include IgE and non-IgE-mediated primary immunological sensitivities, non-immunological food intolerances, and secondary sensitivities. While these various types of reactions are often considered collectively as food allergies, true food allergies represent only a part of the individualistic adverse reactions to foods.

True Food Allergies.

True food allergies are abnormal (heightened) responses of the immune system to components of certain foods (Lemke and Taylor, ). The components of foods that elicit these abnormal immune responses are typically naturally-occurring proteins in the foods (Bush and Hefle, ). True food allergies can be divided into two categories based upon the nature of the immune response—immediate hypersensitivity reactions and delayed hypersensitivity reactions (Lemke and Taylor, ). In immediate hypersensitivity reactions, symptoms start to develop within minutes to an hour or so after ingestion of the offending food.

Immediate hypersensitivity reactions own been noted with numerous foods and can sometimes be fairly severe (Hefle et al., ). Immediate hypersensitivity reactions involve abnormal responses of the humoral immune system with the formation of allergen-specific immunoglobulin E (IgE) antibodies (Mekori, ). In delayed hypersensitivity reactions, symptoms do not start to appear until 24 hours or longer after the ingestion of the offending food (Lemke and Taylor, ). With the exception of celiac disease, which involves an abnormal immunological response to wheat and related grains (Ferguson, ), the role of delayed hypersensitivity reactions to foods remains poorly defined.

Delayed hypersensitivity reactions involve abnormal responses of the cellular immune system with the development of sensitized T cells (Lemke and Taylor, ).

Allergy-Like Intoxications. Certain foods can elicit adverse reactions that resemble true food allergies. These foods contain elevated levels of histamine, one of the principal mediators of allergic reactions in the body (Taylor et al., a). In true food allergies and anaphylactoid reactions, however, histamine is released from intracellular locations (Mekori, ).

In these allergy-like intoxications, histamine is ingested with foods. Histamine poisoning is often known as scombroid fish poisoning because it is frequently associated with consumption of spoiled fish of the scombroid type such as tuna and mackerel (Taylor et al., a). However, histamine poisoning can also happen from the ingestion of spoiled fish such as mahi-mahi and bluefish that are not scombroid fishes (Etkind et al., ; Taylor et al., a). And, histamine poisoning has even been occasionally associated with the ingestion of cheese, especially aged Swiss cheese (Stratton et al., ; Taylor et al., ).

In every of these food products, specific types of bacteria own proliferated and caused the conversion of the amino acid, histidine, into histamine (Stratton and Taylor, ; Sumner et al., ; Taylor et al., ). Ingestion of little amounts of histamine in the diet is a normal occurrence and does not cause any harm. However, when large doses of histamine are ingested with foods, the body’s protective mechanisms can be overwhelmed resulting in histamine poisoning (Taylor, ). Unlike food allergies and sensitivities, every consumers are susceptible to histamine poisoning.

Because this illness is not truly a form of food allergy or sensitivity, it will not be discussed further. It does merit some mention because the similarity in symptoms can cause it to be confused with true food allergy.

Sheet BREAK

Food Intolerances. Food intolerances are abnormal reactions to foods or food components that do not involve the immune system. Several diverse types of food intolerances are also known to exist. These intolerances are metabolic food disorders, anaphylactoid reactions, and idiosyncratic reactions (Taylor, ). Metabolic food disorders are adverse reactions to a food or food component that results from a defect in the metabolism of these foods or some substance therein or from an affect of the food or food component on the body’s normal metabolic processes.

Lactose intolerance is an example of a metabolic food disorder resulting from a defect in the metabolism of a food component (Kocian, ). Favism is an example of a metabolic food disorder resulting from foodborne substances that interfere with normal metabolic processes (Mager et al., ). Anaphylactoid reactions are adverse reactions resulting from the ingestion of foodborne substances that release histamine from cellular stores within the body (Taylor, ). There are no particularly excellent examples of anaphylactoid reactions, although circumstantial evidence suggests that such reactions may happen. Food idiosyncrasies are adverse reactions to foods or food components that happen through unknown mechanisms and which can even include psychosomatic illnesses (Taylor, ).

Sulfite-induced asthma is the best example of an idiosyncratic reaction that has been well documented to happen among certain consumers, although the mechanism remains unknown (Bush and Taylor, ).

Secondary Food Sensitivities. Adverse reactions to foods or food components can happen with or after the effects of other conditions. Examples of such reactions, termed secondary food sensitivities, include lactose intolerance secondary to gastrointestinal disorders such as Crohn’s disease or ulcerative colitis (Metcalfe, a) and drug-induced sensitivities such as the increased sensitivity to tyramine among patients on monoamine oxidase-inhibiting drugs (Blackwell and Marley, ).

IgE-Mediated Food Allergies
This type of food allergy can also be called immediate hypersensitivity, Type I allergy, or food anaphylaxis.

The Greek expression, anaphylaxis, means “against protection” and refers to allergic reactions to foreign protein molecules. IgE is one of five classes of antibodies that are present in the human body and that frolic a role in disease resistance. IgE antibodies are particularly involved in fighting off parasitic infections. Although every humans own low levels of IgE antibodies, only individuals predisposed to the development of allergies produce IgE antibodies that are specific for and recognize certain environmental antigens. These antigens are typically proteins, although only a few of the numerous proteins in nature are capable of stimulating the production of specific IgE antibodies in susceptible individuals (Taylor, ).

The allergens eliciting IgE antibody formation can be found in pollens, mold spores, bee venoms, dust mites, and animal danders in addition to foods (Solomon and Platts-Mills, ).

Pathogenesis. The mechanism of IgE-mediated allergic reactions is depicted in Fig. 2. First, sensitization by the allergen must happen. In the sensitization phase of the response, the allergen stimulates production of specific IgE antibodies. While sensitization can happen with the first exposure to the allergen, that is not always the case.

With honor to food allergens, sensitization does happen most commonly among young infants where the immune response seems to be more likely to be oriented toward an IgE response (Anderson, ). However, even in susceptible infants exposure to most dietary proteins results in oral tolerance, a normal immunologic response that is not associated with adverse reactions, rather than sensitization (Strobel, ). The specific IgE antibodies then attach to mast cells in various tissues and basophils in the blood.

Mast cells and basophils contain granules that are loaded with physiologically athletic chemicals that mediate the allergic response (Church et al., ). On subsequent exposure to the allergenic substance, the allergen cross-links two IgE antibodies on the surface of the mast cell or basophil membrane, stimulating the release into tissues and blood of a host of allergic response mediators. Although numerous mediators own been described, histamine is one of the primary mediators responsible for numerous of the immediate symptoms that happen in IgE-mediated allergic reactions (Simons, ).

Other significant mediators include the various leukotrienes and prostaglandins, some of which are associated with more delayed symptoms that can happen in IgE-mediated, immediate hypersensitivity reactions, the so-called late-phase responses (Peters et al., ).

Sheet BREAK

Symptoms. IgE-mediated food allergies are associated with a wide variety of symptoms, ranging from mild and annoying to severe and life-threatening (Lemke and Taylor, ).

The symptoms can involve the gastrointestinal tract, skin, or respiratory tract (Table 1). Food-allergic individuals generally suffer from only a few of the numerous possible symptoms. The nature and severity of the symptoms experienced by a food-allergic individual may also vary from one episode to the next depending on the dose of the offending food that has been inadvertently ingested, the degree of sensitization to the offending food at the time of the episode, and probably other factors.

Because foods are ingested, gastrointestinal symptoms are often encountered (Anderson, ; Gryboski, ). However, these symptoms can also be involved in other illnesses so their association with food allergies is often hard to decipher. Cutaneous symptoms such as urticaria (hives) and dermatitis (eczema) are also common manifestations of food allergies (Kaplan, ). These symptoms are more definitive for food allergy, although the frequency of dermatitis as a manifestation of food allergy especially, in infants, has only been widely appreciated in the past decade or so (Sampson, ).

Respiratory symptoms are less commonly associated with food allergies than with environmental allergies such as pollen or animal dander allergies (Taylor et al., ). With environmental allergies, the allergens are inhaled, so the primary involvement of respiratory symptoms is understandable. However, ingested food allergens must survive digestive processes and be absorbed to elicit systemic reactions in the respiratory tract. Although few asthmatic individuals experience food-induced asthma, asthma is among the most severe symptoms associated with food allergies (Bousquet and Michel, ).

Food-induced asthma is a risk factor for severe, life-threatening reactions to the offending foods (Sampson et al., ).

Oral allergy syndrome is perhaps the most common manifestation of food allergy (Ortolani et al., ). Oral allergy syndrome is often so mild that it is ignored by afflicted individuals. Oral allergy syndrome involves symptoms confined to the oropharyngeal area including hives, itching, and swelling (Pastorello and Ortolani, ). Unused fruits and vegetables are the foods most frequently associated with oral allergy syndrome (Pastorello and Ortolani, ). Individuals with oral allergy syndrome are generally sensitized to one or more pollens, and react to proteins in specific unused fruits and vegetables that cross-react with the pollen allergens (Calkoven et al., ; Ebner et al., ; van Ree and Aalberse, ).

Examples would include allergic reactions to watermelons and other melons in ragweed-allergic individuals (Enberg et al., ), allergic reactions to celery in mugwort-allergic or birch-sensitized individuals (Ballmer-Weber et al., ; Wuthrich et al., ), and allergic reactions to apples and hazelnuts in birch-allergic individuals (Dreborg, ). Because the allergens in these foods are inactivated on contact with stomach acid and digestive proteases, systemic reactions to these unused fruits and vegetables are rarely encountered (Taylor and Lehrer, ).

Because these allergens are denatured by heating (Dreborg and Foucard, ; Taylor and Lehrer, ), individuals with oral allergy syndrome can generally safely ingest heat-processed forms of the offending food, e.g., apple jelly or apple sauce. Recent evidence indicates that, in contrast to previous assumptions, some individuals with oral allergy syndrome associated with certain foods, such as celery, also may experience more severe systemic reactions on occasion (Ballmer-Weber et al., ).

The most frightening symptom associated with food allergies is anaphylactic shock, which generally involves multiple systems including the gastrointestinal tract, the skin, the respiratory tract, and the cardiovascular system.

Symptoms happen in combination and develop rapidly. Severe hypotension can happen. Death can happen from cardiovascular and/or respiratory collapse within minutes of ingestion of the offending food. Only a few of the numerous people with IgE-mediated food allergies are at risk for such serious manifestations. However, numerous deaths own been attributed to inadvertent exposure to the offending food among individuals with food allergies (Bock et al., ; Sampson et al., ; Yunginger et al., ).

These deaths own involved asthma and/or anaphylactic shock.

In addition to allergic reactions associated with the consumption of foods, occupational food allergies including occupational asthma, hypersensitivity pneumonitis (extrinsic alveolitis), and contact dermatitis can happen amongst food industry employees (O’Neil and Lehrer, ). Such reactions can be triggered in food manufacturing workers by food-derived protein allergens, e.g., green coffee beans, flour, and shellfish, or non-food agents, e.g., honey bees and latex products (Lehrer and O’Neil, ).

These occupational allergies are produced by respiratory exposure to dusty processing environments or cutaneous exposure to specific food products.

Sheet BREAK

Diagnosis. With the wide range of symptoms that can be involved in IgE-mediated food allergies and the possibility of other causes for numerous of these symptoms, the diagnosis of IgE-mediated food allergies can sometimes be challenging (Metcalfe, b). First and foremost, an association must be sought between the ingestion of one or more offending foods and the elicitation of the adverse reaction.

Once a food-associated adverse reaction is well documented, then proof of the existence of an IgE mechanism must be considered. The assistance of an allergist should be sought in the diagnosis of IgE-mediated food allergies. Too often, consumers rely upon self-diagnosis or parental diagnosis. Self-diagnosis and parental diagnosis of reactions in children are problematic because they are often erroneous, leading to the identification of the incorrect foods, and implicate too numerous foods (Bock et al., ).

Careful history-taking including the use of food diaries by an experienced allergist can often identify suspect foods. Elimination diets followed by challenges can sometimes confirm the existence of a food-associated adverse reaction. However, the gold standard for documenting existence of a food-associated adverse reaction is the double-blind, placebo-controlled food challenge (DBPCFC; Bock et al., ). Such clinical challenges are especially useful in situations where the role of a specific food remains somewhat questionable.

Double-blind, placebo-controlled food challenges are not generally done in cases involving serious, life-threatening adverse reactions because of the obvious risks to the patient and the likelihood in such cases that the role of one or more specific foods is rather clear. Once the role of one or more specific foods in the adverse reaction has been established, then the involvement of the IgE mechanism can be documented through skin-prick tests using extracts of the suspect foods (Bock et al., ) or by radioallergosorbent tests (RASTs) where the presence of food-specific IgE antibodies in the blood serum is examined (Adolphson et al., ).

Prevalence.

IgE-mediated food allergies likely affect between 2 and % of the entire population. For numerous years, the overall prevalence estimate for IgE-mediated food allergies has been between 1 and 2% of the entire population (Lemke and Taylor, ). However, a recent random, digit-dial telephone survey in the U.S. indicated that the combined prevalence of peanut and tree nut allergies was an estimated % (Sicherer et al., ). And, a similar telephone survey in the United Kingdom indicated that the estimated prevalence of peanut allergy alone was % (Emmett et al., ).

While one could criticize the use of telephone surveys, it is unlikely that numerous consumers would mis-diagnose peanut or tree nut allergies since the symptoms are profound and generally fairly immediate. Thus, these surveys may be reasonably dependable and a excellent indication that previous estimates based solely on clinical impression were incorrect. Certainly, if peanut and tree nut allergy alone account for more than 1% of IgE-mediated food allergy, then the overall prevalence of food allergy in the entire population likely exceeds 2%.

Infants (1–3 years of age) and children are more commonly affected by food allergies than other age groups (Taylor et al., ). Among infants younger than 3 years, the prevalence of food allergies appears to be in the range of 5% to 8% (Sampson, ).

The prevalence of food allergy among young infants (<1 year of age) has been studied more thoroughly than has the prevalence among older children and adults.

A much higher proportion of the public believes that they own food allergies because of self-diagnosis, parental diagnosis, and misconceptions about the definition of food allergy even among some physicians (Bock et al., ; Sloan, ). Studies own shown that 10 to 20% of the consuming public believes that they or someone in their family has a food allergy (Chiaramonte et al., ; Sloan, ).

Some believe, on the basis of the impressions of clinicians involved in allergy practice for several decades, that the prevalence of IgE-mediated food allergies is increasing.

An increase in prevalence, however, is hard to confirm because excellent baseline data from earlier years for comparative purposes are lacking. Certainly, the awareness of food allergy has increased. More individuals may seek specialized medical attention from allergists as a result of this increased awareness. But, almost everyone agrees that the prevalence of severe food allergies seems to be increasing. The reasons for this apparent increase are unknown. Numerous severely affected individuals own food-induced asthma as one of the manifestations of their allergic reaction. The overall prevalence of asthma is definitely increasing in the U.S. for unknown reasons (Beasley et al., ).

While food-induced asthma is a little part of the entire asthma population, the prevalence of food-induced asthma may be increasing in concert with the overall increase in prevalence of asthma.

Most Common Allergenic Foods.
The prevalence of allergies to specific foods is not precisely known. Cows’ milk allergy appears to be among the more prevalent food allergies in infants. This is not surprising given the importance of milk in baby feeding practices. The prevalence of cows’ milk allergy among infants under the age of two in Sweden, Denmark, and Australia has been studied and found to be approximately 2% in every three countries in well-conducted clinical studies involving groups of unselected infants followed from birth to the age of two years (Hill et al., ; Host and Halken, ; Jakobsson and Lindberg, ).

The prevalence of milk allergy is known to decrease with age (Bock, ), but the exact prevalence of milk allergy among other age groups is unknown. The prevalence of other specific food allergies has not been established in controlled clinical trials using unselected population groups. The comparative prevalence of various specific food allergies can be discerned from studies involving groups of individuals with probable food allergies. In the U.S., eggs and peanuts are also common allergenic foods for infants, along with soybeans, tree nuts, fish, and wheat (Bock and Atkins, ; Burks et al., ; Sampson and McCaskill, ).

Among adults in the U.S., peanuts are probably the most common allergenic food (Taylor et al., ). Seafood allergies, especially to crustaceans (shrimp, crab, lobster), are also rather common among adults (Lehrer et al., ). Fewer studies own been conducted on the prevalence of specific types of food allergies in adults in the U.S. or other countries. The prevalence of specific types of food allergies may vary among population groups based upon their eating habits (Taylor et al., ). Peanut allergy appears to be more common in North America than in other parts of the world. This observation may relate to the popularity of peanut butter in North America.

As other countries, such as the United Kingdom, own adopted the North American affection for peanuts and peanut products, the prevalence of peanut allergy in those countries appears to be rising (Emmett et al., ). Another example would be buckwheat allergy. Buckwheat allergy appears to be rather common among adults in certain southeast Asian countries such as Japan and South Korea (Kang and Min, ). In contrast, buckwheat allergy would be rather unusual in the U.S. The difference is likely due to the popularity of buckwheat noodles in the cuisine of certain southeast Asian countries. Such observations own profound implications for product developers.

If a highly successful buckwheat product was introduced into the U.S. or if buckwheat noodles became favorite in American Asian cuisine, the prevalence of buckwheat allergy would likely increase.

Sheet BREAK

The Large Eight. Eight foods or food groups are thought to account for more than 90% of every IgE-mediated food allergies on a worldwide basis (Bousquet et al., ; FAO, ). These foods or food groups are milk, eggs, fish (all species of finfish), crustacea (shrimp, crab, lobster, crayfish), peanuts, soybeans, tree nuts (almonds, walnuts, pecans, cashews, Brazil nuts, pistachios, hazelnuts also known as filberts, pine nuts also known as pinyon nuts, macadamia nuts, chestnuts, and hickory nuts), and wheat.

In , an expert consultation of the Food and Agriculture Organization of the United Nations sure that these eight foods or food groups were the most common causes of food allergy on a worldwide basis (FAO, ). Subsequently this list was adopted by the Codex Alimentarius Commission in (CAC, ). These foods and food groups own come to be known as the “Big Eight” (Table 2). More than other foods own been documented as causing food allergies less frequently (Hefle et al., ).

Basically, any food that has protein has the potential to elicit an allergic reaction among susceptible individuals.

Beyond the Large Eight, in certain geographic regions other foods or food groups may frequently cause IgE-mediated food allergies. Celery allergy, for example, is rather common in some European countries (Wuthrich et al., ). The prevalence of buckwheat allergy in southeast Asia has already been mentioned. And, sesame seed allergy is extremely common in middle Eastern countries and countries where the ethnic population of middle Easterners is high; this may be due to the popularity of tahini, a paste made from sesame seeds, in the diets (Kanny et al., ).

Several countries including Canada own decided to add sesame seeds to the list of commonly allergenic foods for that country. A few other foods are worthy of mention because, although they less frequently cause allergies, they own been associated with severe reactions. These foods include molluscan shellfish (clams, oysters, etc.), sesame seeds, poppy seeds, sunflower seeds, cottonseed, and certain other legumes beyond peanuts and soybeans (the various types of dry beans, peas, lentils, and garbanzo beans also known as chick peas) (Atkins et al., ; Gall et al., ; Kagi and Wutrich, ; Kalyoncu and Stalenheim, ; Kanny et al., ; Maeda et al., ; Martin et al., ; Noyes et al., ).

However, a rather large percentage of the or more other allergenic foods has been reported to elicit severe allergic reactions in isolated cases (Hefle et al., ).

Food Allergens. The allergens in foods are almost always naturally occurring proteins. Foods contain millions of individual proteins, but only a comparative few of the proteins own been documented to be allergens (Bush and Hefle, ; Taylor, ). Some foods such as milk, eggs, and peanuts are known to contain multiple allergenic proteins (Bush and Hefle, ).

Other foods such as Brazil nuts, shrimp, and codfish contain only one major allergenic protein (Bush and Hefle, ). However, the majority of the proteins, even those from commonly allergenic foods, are incapable of eliciting IgE production. Although the common allergenic foods listed above tend to be excellent sources of protein, other common protein-rich foods such as beef, pork, chicken, and turkey are rarely allergenic. No common structural features own allowed distinctions to be made between those proteins that are capable of eliciting IgE production and those that are not. Allergenic proteins, however, tend to be major proteins in the implicated foods, resistant to digestion, and stable to processing operations, particularly heat processing (Taylor and Lehrer, ).

Development of IgE-Mediated Food Allergies.

Genetics frolic an significant role in the development of IgE-mediated allergies of every types, including food allergies (Kjellman and Bjorksten, ). Allergies are much more likely to develop in children born to parents who own allergies (either to food, pharmaceutical, or environmental allergens) than amongst children born to parents with no history of allergies (Taylor et al., ). However, the nature of the allergy that develops is not genetically controlled. Therefore, the children of pollen-allergic parents are at increased risk for development of food allergies as are the children of food-allergic parents. The risk is greater if both parents own allergies than it is if only one parent has allergies.

Infants are the most likely to develop food allergies (Sampson, ; Taylor, ).

However, sensitization to foods can happen at any age. Infants do not appear to develop allergies in utero (Kjellman and Bjorksten, ), but can be sensitized during the first few days of life. Obviously, the newborn baby encounters through the first few years of life dozens of new foods and probably hundreds of thousands of food proteins that own antigenic and possibly allergenic potential. For most of these foods and their proteins, infants develop oral tolerance (Strobel, ). Infants appear to be at increased risk for the development of IgE-mediated food allergies in part because their digestive processes may not be fully developed but primarily because they own not yet had the chance to develop oral tolerance.

Certain foodborne proteins seem to be much more likely than others to cause allergic sensitization (Bush and Hefle, ). The factors involved in sensitization and the development of IgE-mediated food allergies are not yet fully understood.

Sheet BREAK

Prevention of IgE-Mediated Food Allergies. The prevention of the development of IgE-mediated food allergies among high-risk infants (those born to parents with histories of allergies) has been a long-sought goal.

However, the results of several large clinical trials of high-risk infants followed for several years propose that the development of IgE-mediated food allergies can be delayed but not prevented (Zeiger and Heller, ). The maternal diet during pregnancy does not seem to be a factor (Zeiger and Heller, ), because sensitization does not happen in utero. The avoidance of commonly allergenic foods such as cows’ milk, eggs, and peanuts in the baby diet during the first few years of life often delays the development of food allergies, but food allergies may still develop after solid foods are introduced (Hattevig et al., ; Zeiger and Heller, ).

Avoidance can be accomplished through breast-feeding or the feeding of hypoallergenic baby formula (Kjellman and Bjorksten, ; Zeiger and Heller, ). Numerous pediatricians recommend breast-feeding for infants born to parents with histories of IgE-mediated allergies. Lactating women can apparently transmit potentially sensitizing levels of food allergens through their milk to nursing infants (Van Asperen et al., ). Apparently, intact or partially intact allergenic proteins are capable to survive maternal digestive processes and be absorbed via the lymph and transferred immunologically intact into breast milk (Van Asperen et al., ).

Infants own been sensitized through breast-feeding to peanuts, cows’ milk, and eggs (Van Asperen et al., ). The avoidance of peanuts in the maternal diet during the lactation period is often advocated as a preventive measure. However, the exclusion of milk and eggs from the maternal diet during lactation is not generally recommended due to their nutritional importance coupled with the low likelihood of allergic sensitization through breast-milk (Taylor et al., ).

The use of hypoallergenic baby formula to prevent or delay the development of IgE-mediated food allergies is less commonly practiced. However, the use of partial whey hydrolysate formulae for this purpose may show some promise (Vandenplas et al., ), although such partial hydrolysates are not safe for consumption by infants who are already sensitized to cows’ milk (Businco et al., ; Ellis et al., ). Apparently, the partial hydrolysis of the whey proteins increases the likelihood of the development of oral tolerance as opposed to allergic sensitization.

Natural History of IgE-Mediated Food Allergies. Most food allergies developed in infancy are outgrown in infancy or early childhood.

Numerous infants outgrow their food allergies, often within a matter of a few months (Bock, ; Hill and Hosking, ). Allergies to certain foods such as cows’ milk, eggs, and soybeans are much more likely to be outgrown than allergies to other foods such as peanuts (Bock, ; Bock and Atkins, ). Peanut allergy is almost never outgrown. The loss of allergic sensitivity to a specific food probably results from the development of immunological, oral tolerance (Taylor et al., a).

However, the basis for the differences between specific foods (e.g., milk vs. peanuts) in the development of oral tolerance is not understood.

Cross-Reactions between Related Allergenic Foods. Allergic consumers sometimes experience cross-reactions between closely related foods. For example, with the crustacea, most sensitive individuals are allergic to every of the various species of shrimp, crab, lobster, and crayfish (Lehrer, ). However, these individuals can often eat other seafoods including finfish and molluscan shellfish.

Similar cross-reactivity also exists between cows’ milk and goats’ milk (Bellioni-Businco et al., ) and between eggs of various avian species (Langeland, ). With other food groups, the situation can be fairly complicated. For example, peanuts are the most commonly allergenic legumes. Most peanut-allergic individuals can eat other legumes without incident (Bernhisel- Broadbent and Sampson, ). A few peanut-allergic individuals are also allergic to soybeans (Herian et al., ), although this may not necessarily represent true cross-reactivity. With fish, individuals often experience reactions to more than one species of fish, but some fish are tolerated by some fish-allergic individuals and no definite patterns of reactivity own been identified (Bernhisel-Broadbent et al., ; de Martino et al., ).

Cross-Reactions between Food and Environmental Allergens.

Cross-reactions are frequently observed between pollens and certain foods, especially fruits and vegetables (Ballmer-Weber et al., ; Calkoven et al., ; van Ree and Aalberse, ; Wuthrich et al., ). This is the oral allergy syndrome, which typically involves mild reactions as previously mentioned. Examples include cross-reactions between birch pollen and apples, ragweed pollen and melons, and mugwort pollen and celery (Ballmer-Weber et al., ; Calkoven et al., ; Enberg et al., ; van Ree and Alberse, ; Wuthrich et al., ). Cross-reactions own also been noted between latex allergies, a common problem among health-care workers, and certain foods including bananas, kiwis, avocados, and chestnuts (Blanco et al., ).

Effect of Food Processing on Allergens.

As mentioned earlier, the allergens in foods are typically proteins that are stable to heat processing (Taylor and Lehrer, ). So, heat-processed forms of commonly allergenic foods often retain their allergenicity (Herian et al., ; Nordlee et al., ). The only exception would be the pollen-related allergens found in unused fruits and vegetables and involved in oral allergy syndrome; these allergens are generally destroyed by heat processing (Dreborg and Foucard, ), although the necessary extent of the heat process has not been well documented in most cases.

For the most common allergenic foods, every forms of those foods should be considered allergenic unless proven otherwise. Testing has indicated that most forms of peanuts and soybeans, for example, retain their allergenicity (Herian et al., ; Nordlee et al., ). Other processing techniques own not been so well investigated for their effects on the allergenicity of the resulting products. Since allergens are resistant to proteolysis, fermentation generally fails to eliminate allergenicity (Taylor and Lehrer, ).

For example, although fermented soybean products are reduced in allergenicity, some allergenic activity is retained (Herian et al., ).

Sheet BREAK

If the protein part is removed during processing, however, the resulting product or ingredient might be safe because the allergen has been removed. The classic example is the processing of edible oils from peanuts and soybeans (Bush et al., ; Hourihane et al., a; Taylor et al., ). Clinical challenge trials in peanut- and soybean-allergic individuals own documented that highly refined peanut and soybean oil are safe for individuals with allergies to the source material (Bush et al., ; Hourihane et al., a; Taylor et al., ).

Other ingredients may be derived from allergenic sources.

Examples include certain flavoring formulations, starch, lecithin, and gelatin. Flavors can occasionally contain protein residues from allergenic foods (Taylor and Dormedy, ). Starch is often made from corn or some other source that is rarely allergenic. Occasionally, starch is made from wheat, although the level of protein residues is fairly low and adverse reactions to wheat starch own not been reported. Lecithin can be made from either soybean or egg and can contain allergenic residues (Muller et al., ).

However, the degree of risk posed by the low residual levels of soybean allergens in lecithin remains unknown. Gelatin is most commonly made from beef and pork, foods that are rarely allergenic (Sakaguchi et al., ). However, gelatin can also be made from fish skins. The allergenicity of fish gelatin remains unknown (Sakaguchi et al., ).

Treatment. Allergic reactions to foods can be treated with certain drugs (Furukawa, ; Simons, ). Antihistamines can counteract the effects of histamine (Simons, ), although these drugs do not counteract the effects of the other mediators released from basophils and mast cells. Epinephrine (adrenaline) is considered the life-saving drug for individuals at risk of severe anaphylactic shock-type reactions to foods (Sampson et al., ).

Epinephrine is available in self-injectable form. Consumers with a history of severe anaphylactic reactions to foods should own a prescription for epinephrine and carry the medication at every times. To be most effective, epinephrine must be istered early in the course of the allergic reaction. However, an examination of severe food-allergic reactions resulting in deaths or near-deaths reveals a delay in the istration of epinephrine as a key contributing factor to the severe outcome (Sampson et al., ).

The specific avoidance diet is the only prophylactic approach to the treatment of food allergies (Taylor et al., a; Taylor et al., ).

For example, individuals allergic to peanuts must simply avoid ingesting peanuts. The construction of safe and effective avoidance diets is often a challenge for individuals with food allergies. With packaged foods, these individuals must spend considerable time in the scrutiny of ingredient declarations on product labels. They must be taught to recognize the numerous terms that may signify the presence of food components or ingredients derived from their offending food(s). Some foods, especially in foodservice settings, are sold without ingredient statements.

Clearly, the allergic consumer can encounter numerous hazardous situations in such circumstances and must be trained to be extremely vigilant. Also, exposure to extremely little amounts of the offending food may be sufficient to elicit allergic reactions in some sensitive individuals, further complicating the necessary vigilance in the implementation of effective avoidance diets.

Threshold Doses for Allergenic Foods. As noted, individuals with IgE-mediated food allergies will experience symptoms on exposure to little amounts of the offending food.

The interaction of a little quantity of the allergen with specific IgE antibodies on the surface of the mast cell or basophil membrane triggers the release of massive quantities of mediators, which accounts for the low degree of threshold. The precise threshold doses for allergenic foods own not been carefully investigated and are likely to be variable from one allergic individual to another. In a recent study, Hourihane et al. (b) demonstrated that a group of individuals with peanut allergy displayed diverse thresholds for peanuts.

The most sensitive individual among 12 tested subjects experienced an objective reaction when exposed to 2 mg of peanut protein. Other patients in the group did not even reply to the highest dose used in the challenge trial which was 50 mg of peanut protein. While this experiment clearly demonstrates that the threshold level is not zero, the threshold dose is fairly low. Whether other allergenic foods own thresholds as low as those for peanuts remains to be determined.

Allergenicity of Foods Produced Through Agricultural Biotechnology. In the genetic modification of foods, genes are transferred from one organism to another.

Because these genes code for the expression of a specific protein, novel proteins are expressed in the transgenic variety as a result. Because every allergens are proteins, the theoretical possibility exists that these novel proteins might be allergenic or that they might become allergenic. However, only a few of the numerous proteins found in nature are allergenic, so the probability of the transfer of an allergen is rather low.

The potential allergenicity of the novel proteins expressed in the new varieties produced through agricultural biotechnology should be assessed in every case.

Sheet BREAK

The potential allergenicity of the novel proteins in transgenic varieties can be assessed (FAO/WHO, ; Metcalfe et al., ; Taylor and Hefle, a). If a gene is transferred from a known allergenic source, the potential allergenicity of the expressed novel protein can be assessed with reasonable certainty by evaluating its reactivity by specific serum screening with serum containing IgE antibodies from individuals with well documented allergies to the source material.

This assessment approach was demonstrated to be effective when it was sure that a Brazil nut protein transferred into soybeans to correct the inherent methionine deficiency of soybeans was the heretofore unidentified major allergen from Brazil nuts (Nordlee et al., ). The company involved abandoned further commercial interest in these transgenic soybeans as a result. It should be emphasized that genes are not often obtained from known allergenic sources in the development of commercial transgenic varieties.

However, when genes are transferred from known allergenic sources, it must be assumed that the gene encodes for an allergenic protein unless proven otherwise.

More typically, genes are obtained from sources with no history of allergenicity. In these situations, a decision-tree approach is advocated for the assessment of the potential allergenicity of the novel protein. While no single test can perfectly predict the potential allergenicity of a specific novel protein from a source with no history of allergenicity, the application of a series of tests provides reasonable assurance that the novel protein is not likely to become an allergen.

Several decision-tree approaches own been developed (FAO/WHO, ; Metcalfe et al., ; Taylor and Hefle, a). These approaches rely upon evaluation of the source of the gene and its history of allergenicity, the sequence homology of the novel protein to known allergens, the immunoreactivity of the novel protein with serum IgE from individuals with known allergies to the source of the transferred gene, the immunoreactivity of the serum IgE from individuals with known allergies to sources that are broadly related to the source of the novel gene (e.g., grass pollen allergic individuals in cases where the gene is obtained from monocot sources), the pepsin resistance or digestive stability of the novel protein, and the immunogenicity of the novel protein in validated animal models (Fig.

3). Other factors especially the level of expression of the novel protein in the food are also likely to be significant since allergies are generally elicited by food proteins where dietary exposure is comparatively high.

Foods produced through agricultural biotechnology including corn, soybeans, canola, and potatoes are already reaching the consumer marketplace. The potential allergenicity of the novel proteins expressed in these commercial products has been assessed using the approaches indicated above. The novel proteins in these approved transgenic varieties are not obtained from known allergenic sources, are not structurally homologous to known food or environmental allergens, and are sensitive to digestive proteolysis.

Furthermore, the novel proteins are expressed at extremely low levels in the edible portions of these modified crops. Thus, the likelihood of allergenicity from this current generation of crops produced by agricultural biotechnology is virtually nil.

Considerable publicity has surrounded one specific transgenic variety, the so-called StarLink™ corn. StarLink corn was never approved for human use, but was unfortunately approved for animal feed use. When segregation failed, some StarLink corn residues were found in corn-based food products intended for human consumption. Although the gene inserted in StarLink corn was obtained from a source with no history of allergenicity and the novel protein was not structurally similar to known food or environmental allergens, the novel protein was comparatively more resistant to digestive proteolysis than other novel proteins that had been approved for other genetically modified crops.

For this reason, StarLink corn was never approved for human consumption. However, given the extremely low level of exposure to the novel protein in StarLink corn in corn-based food products, the likelihood of allergic sensitization to this specific novel protein is low. Despite that and due to the concerns about the potential allergenicity of this transgenic variety, it has been withdrawn from the marketplace, although traces may remain for one or more growing seasons. This episode emphasizes the importance of assessing the potential allergenicity of transgenic varieties as part of the overall safety evaluation process.

Agricultural biotechnology can also be used to decrease the inherent allergenicity of foods.

The proteins in specific foods that are responsible for allergic reactions could be removed or altered through agricultural biotechnology. While no commercial examples exist yet of the application of this possibility, it is an athletic area of research with peanuts.

Sheet BREAK

Non-IgE Cell-Mediated Reactions
As noted earlier, cell-mediated allergic reactions, also known as delayed hypersensitivity reactions, own an onset time of 6–24 hours after ingestion of the offending food.

The reactions develop slowly, reaching a peak at approximately 48 hours and then slowly subsiding over 72–96 hours. Cell-mediated food allergies involve the interaction between specific antigens or allergens from the food and sensitized, tissue-bound T cells that release inflammatory mediators when sensitized (Sampson, ). The role of cell-mediated reactions in food allergies remains somewhat uncertain. Compelling and mounting evidence has accumulated, however, indicating that celiac disease occurs through a T cell-mediated mechanism (Ferguson, ; Strober, ).

Celiac Disease.

Also known as celiac sprue or gluten-sensitive enteropathy, celiac disease is a malabsorption syndrome occurring in sensitive individuals upon the consumption of wheat, rye, barley, triticale, spelt, and kamut (Ferguson, ; Lemke and Taylor, ).

What is the most common food allergies

The role of oats in celiac disease has recently been questioned. Apparently, oats and oat products that are totally free of wheat, rye, and barley, are safe for celiac sufferers to consume (Janatuinen et al., ). After consumption of the offending grains or products made from these grains, the absorptive epithelial cells in the little intestine are damaged by an inflammatory process (Ferguson, ). As a result, absorption of nutrients through the epithelium is compromised. The loss of absorptive function along with the ongoing inflammatory process results in a severe malabsorption syndrome characterized by diarrhea, bloating, weight loss, anemia, bone pain, chronic fatigue, weakness, muscle cramps, and, in children, failure to acquire weight and growth retardation (Lemke and Taylor, ; Skerritt et al., ).

A part of wheat, the gliadin part, and related part in barley and rye are associated with initiation of celiac disease in susceptible individuals (Skerritt et al., ).

Celiac disease is an inherited trait, but the inheritance is complicated and poorly understood. Celiac disease occurs in about 1 of every individuals in the U.S. (Kasarda, ). In some other parts of the world, celiac disease occurs more frequently. The highest prevalence occurs among individuals in certain regions of Europe (Greco et al., ; Kasarda, ).

Celiac disease seems to happen more frequently among Europeans than among Americans of European descent for unexplained reasons. Celiac disease rarely occurs among individuals of Chinese or African descent (Ferguson, ).

The treatment of celiac disease involves the avoidance of wheat, rye, barley, triticale, spelt, kamut, and oats and products of these grains (Hartsook, ). The threshold dose of gliadin and related protein fractions needed to provoke celiac disease in sensitive individuals is not precisely known, but symptoms can be elicited by ingestion of little amounts of these grains (Lemke and Taylor, ).

If a gluten-free diet is followed, the symptoms of celiac disease will resolve and the absorptive function of the little intestine will be restored. Most celiac sufferers adhere to extremely strict gluten-free diets. In the absence of information on the safety of products made from the offending grains, affected individuals often select to avoid products that contain remarkably little amounts of protein from these sources including rye alcohol, wheat starch, malt extract, and vinegar. The wisdom of such severely restricted avoidance diets remains to be established.

Food Intolerances
In contrast to true food allergies, food intolerances happen through non-immunological mechanisms.

However, love true food allergies, food intolerances affect some individuals in the population but not every. Individuals suffering from food intolerances can generally tolerate little amounts of the offending food or food ingredient in their diet without ill effects. Food intolerances can be divided into three categories: anaphylactoid reactions, metabolic food disorders, and idiosyncratic illnesses.

Anaphylactoid Reactions. In IgE-mediated food allergies, the release of histamine and other mediators from the mast cells and basophils is mediated by the interaction of IgE with proteinaceous allergens, as described earlier.

In contrast, anaphylactoid reactions are caused by substances that bring about the release of the same mediators from mast cells without the involvement of IgE (Lemke and Taylor, ). Some substance in the implicated food is presumed to destabilize the mast cell membranes allowing for the spontaneous release of histamine and the other mediators. However, no such histamine-releasing substance has ever been isolated or identified in foods, although this mechanism is well established with certain drugs.

Strawberry sensitivity is generally cited as the best example of an anaphylactoid reaction. Although strawberries are known to cause adverse reactions (frequently urticaria) in susceptible individuals, there is little evidence for the existence of an IgE-mediated mechanism. Strawberries contain little protein, and no evidence has been found for the existence of a strawberry allergen. Furthermore, there is no evidence for the existence of strawberry-specific IgE in the sera of strawberry-sensitive individuals. Spontaneous histamine release is thus a plausible mechanism. However, if a substance exists in strawberries that destabilizes mast cell membranes, that substance has yet to be identified.

The possibility that strawberry sensitivity is a form of oral allergy syndrome has not yet been excluded, and is an equally plausible mechanism.

Sheet BREAK

Metabolic Food Disorders. Metabolic food disorders result either from inherited defects in the ability to metabolize some component of food or from a genetically sure, enhanced sensitivity to some foodborne chemical that occurs through an altered metabolic pattern (Lemke and Taylor, ).

Lactose intolerance is an example of an illness that occurs when a genetic deficiency affects the host’s ability to metabolize a food component (Kocian, ). In lactose intolerance, an inherited deficiency occurs in the quantity of the enzyme, β-galactosidase, leading to an impaired ability to digest lactose. Favism is an example of a genetic deficiency that enhances the sensitivity to a foodborne chemical. In favism, a genetic deficiency in glucosephosphate dehydrogenase in the erythrocyte results in an enhanced sensitivity to several hemolytic substances that happen naturally in fava beans (Mager et al., ).

These two metabolic food disorders are the most common and best understood illnesses in this category of food intolerances.

Lactose Intolerance. Lactose is a dissaccharide and the principal sugar in milk. Normally, lactose is hydrolyzed into its constituent monosaccharides, galactose and glucose, in the little intestinal mucosa. These monosaccharides can then be absorbed and used as metabolic sources of energy. In lactose intolerance, the activity levels of β-galactosidase, the key hydrolytic enzyme that exists in the mucosal membranes of the little intestine, are diminished (Houts, ; Suarez and Savaiano, ).

Since lactose cannot be absorbed in the little intestine unless it is hydrolyzed to glucose and galactose, the undigested lactose passes into the colon where it encounters large populations of bacteria. The colonic bacteria metabolize the lactose to CO2, H2, and H2O (Lemke and Taylor, ). Abdominal cramping, flatulence, and frothy diarrhea are the predominant symptoms of lactose intolerance (Bayless et al., ) and are the direct result of the action of the colonic bacteria on lactose. The symptoms vary in intensity in concert with the individual level of activity of β-galactosidase in the little intestine and the quantity of lactose ingested.

Lactose intolerance is a fairly common metabolic food disorder.

Lactose intolerance is especially prevalent among some ethnic groups in the world including Greeks, Arabs, Jews, black Americans, Hispanics, Japanese, and other Asians (Houts, ; Suarez and Savaiano, ). Only about % of Caucasians are affected (Suarez and Savaiano, ). Lactose intolerance can own its onset at any age, occurring as early as the age of three (Simoons, ). However, lactose intolerance tends to worsen with advancing age and is often more common and more severe among the elderly (Houts, ; Simoons, ).

What is the most common food allergies

The level of intestinal b-galactosidase is generally sufficient at birth to permit digestion of lactose in mother’s milk, but susceptible individuals suffer as a result of decreased activity of this enzyme as life progresses. Lactose intolerance may also happen on a more transitory basis on occasion, secondary to another intestinal illness or infection such as a bout of viral gastroenteritis (Metcalfe, b). Secondary lactose intolerance tends to subside rather quickly after the original illness is resolved.

Individuals with lactose intolerance are capable to control their symptoms through the avoidance of dairy products containing lactose (Lemke and Taylor, ).

However, numerous lactose-intolerant individuals can tolerate some lactose in their diets. The degree of tolerance for lactose is individualistic and variable among such individuals. Yogurt, sour cream, and acidophilus milk that contain athletic cultures of bacteria with b-galactosidase activity, are better tolerated by lactose-intolerant individuals than other dairy products (Kolars et al., ). Lactose-hydrolyzed milk is also available in the marketplace (Paige et al., ).

And, lactose-intolerant individuals can add b-galactosidase to milk just before consumption, and this seems to be an effective practice (Barillas and Solomons, ). Certainly, the level of tolerance for dairy products is much higher with lactose intolerance than it is with IgE-mediated cows’ milk allergy (Taylor, ).

Favism. Individuals with an inherited deficiency of the enzyme, glucose phosphate dehydrogenase (G6PDH), in their erythrocytes are susceptible to favism. Symptoms happen after consumption of fava beans or the inhalation of pollen from the Vicia faba plant (Mager et al., ).

Fava beans contain vicine and convicine, naturally occurring oxidants that are capable to damage the erythrocyte membranes of G6PDH-deficient individuals causing hemolysis and the symptoms of hemolytic anemia (Marquardt, ). G6PDH is a critical enzyme in erythrocytes because it helps to maintain adequate levels of the reduced form of glutathione (GSH) and nicotinamide adenine dinucleotide phosphate (NADPH). GSH and NADPH assist to avert oxidative damage to erythrocytes.

In individuals who are G6PDH-deficient, this protective mechanism is nonfunctional and the oxidants in fava beans can exert their hemolytic effects. In rare cases with repeated exposure, more severe symptoms can happen including hemoglobinuria, jaundice, and renal failure. The onset time after ingestion of the fava beans ranges from 5 to 24 hours. The illness is self-limited, however, with symptoms resolving promptly and spontaneously upon avoidance of further exposure.

G6PDH deficiency is extremely common and affects approximately million individuals on a worldwide basis (Mager et al., ).

The prevalence is highest among Oriental Jewish groups in Israel, Sardinians, Cypriot Greeks, African Americans, and certain African populations. This inherited trait is virtually absent among Caucasians, North American Indians, and Eskimos. Despite the high prevalence of G6PDH deficiency, favism is an unusual occurrence because fava beans are not frequently eaten except in Mediterranean and Middle Eastern locales.

Idiosyncratic Illnesses
Some individualistic adverse reactions to foods are idiosyncratic in that the mechanism for these illnesses is unknown. Numerous reports, mostly anecdotal, own occurred regarding illnesses in certain individuals attributed to certain specific foods or food ingredients.

Conceivably, a large number of diverse mechanisms could be involved in these idiosyncratic reactions. The symptoms involved in idiosyncratic reactions range from unimportant to severe, life-threatening reactions (Taylor et al., b).

Sheet BREAK

The role of specific foods or food ingredients in the causation of these idiosyncratic reactions remains to be sure in numerous cases. The cause-and-effect relationships can only be established through carefully controlled DBPCFCs (Taylor et al., b). A positive DBPCFC would definitely confirm that the specific food or food ingredient is involved in the specific adverse reaction.

The mechanism of the adverse reaction, however, cannot be sure from the positive DBPCFC alone. A negative DBPCFC indicates either that foods are not involved in causation of the reaction or at least that the specific food or food ingredient used in the challenge was wrongly incriminated. Unfortunately, DBPCFCs are rarely performed to establish convincingly that a specific food or food ingredient is associated with a specific idiosyncratic reaction.

The role of specific foods or food ingredients are firmly established in a few of the numerous alleged foodborne idiosyncratic reactions.

Sulfite-induced asthma is perhaps the best example (Bush and Taylor, ). In the case of sulfite-induced asthma, numerous clinicians own documented the role of sulfites in the provocation of asthma in dozens of patients using DBPCFC protocols (Bush and Taylor, ). Aspartame has been identified as a causative factor in two subjects using DBPCFC (Kulczycki, ). However, other cases of aspartame-induced urticaria own not been identified so this may be a rather rare phenomenon.

For numerous other alleged idiosyncratic reactions to specific foods or food ingredients, the association with the specific food or food ingredient has not been conclusively documented through DBPCFCs.

Examples would include the role of chocolate or aspartame in migraine headache; the roles of BHA, BHT, tartrazine, benzoates, or parabens in chronic urticaria; the role of tartrazine in asthma; the role of monosodium glutamate (MSG) in asthma or MSG Symptom Complex; and the role of sugar in aggressive behavior (Bush and Taylor, ). A thorough critique of the numerous studies that own been conducted on the role of these foods or food ingredients in the causation of these idiosyncratic reactions is beyond the scope of this specific review.

However, extremely few of the clinical studies own used double-blind and placebo-controlled trial designs. Furthermore, numerous of the studies own involved individuals with chronic, episodic symptoms such as chronic urticaria or asthma and the clinical investigators own removed critical medications from the patients before initiating the challenge trials. In such cases, the observed symptoms might be due either to the challenge substance or to the withdrawal of medications that controlled the condition.

With such critical clinical design flaws, the role of these specific foods and food ingredients in  these specific idiosyncratic illnesses remains unproven. Furthermore, psychological disorders may be involved in perceived reactions to specific foods or food ingredients (King, ; Selner and Staudenmayer, ).

In a few cases, the role of specific foods or food ingredients in idiosyncratic reactions has been disproven by careful clinical investigations. However, consumers may persist in their belief that such reactions happen. The outstanding example of such a reaction is the role of artificial food colors in hyperkinetic behavior in children. Several decades ago, Dr.

Benjamin Feingold implicated artificial food colorants as causative factors in hyperkinesis on the basis of poorly controlled trials and anecdotal experiences (Feingold, ). The resulting publicity on the Feingold hypothesis was considerable, and, consequently, numerous consumers became convinced of a relationship between ingestion of artificial food colorants and provocation of hyperkinetic behavior in children. Subsequently, several double-blind, placebo-controlled challenge trials own been conducted with artificial food colorants and own demonstrated convincingly that few, if any, hyperkinetic children are adversely affected by the ingestion of these food colorants (Harley et al., a).

Despite this evidence, numerous consumers persist in their belief regarding the role of artificial food colorants in hyperkinetic behavior.

A similar situation exists with honor to monosodium glutamate where the involvement of MSG intake in the so called Chinese Restaurant Syndrome, now more appropriately called MSG Symptom Complicated, has been alleged so often that it is now accepted as fact by numerous consumers. However, the role of MSG in MSG Symptom Complicated has not been corroborated in carefully controlled clinical challenge studies (Kenny, ; Tarasoff and Kelly, ).

More recently, MSG intake has been linked to asthma (Allen et al., ). However, the role of MSG in provocation of asthma seems questionable at best when patients are evaluated using a DBPCFC protocol (Bush and Taylor, ). The alleged role of tartrazine, also known as FD&C Yellow #5, in asthma and chronic urticaria is also extremely questionable in the light of DBPCFCs (Bush and Taylor, ; Stevenson et al., ). Yet, undeclared tartrazine remains the basis for a large number of FDA recalls.

Sulfite-Induced Asthma. Sulfiting agents allowed for use in foods include sulfur dioxide, potassium metabisulfite, sodium metabisulfite, potassium bisulfite, sodium bisulfite, and sodium sulfite.

Sulfiting agents own been used as food ingredients for numerous years, because they own numerous significant technological benefits (Taylor et al., b). Sulfites also happen naturally in some foods, especially fermented foods (Taylor et al., b). However, residual levels of sulfites in foods vary from a few ppm arising mostly from natural sources, to less than 10 ppm to >1, ppm as a result of additive usage.

Sheet BREAK

Although sulfites own been used for centuries, they own been implicated as triggers of asthma in some sensitive individuals only in recent years (Bush and Taylor, ; Stevenson and Simon, ).

The reactions generally happen within a few minutes after the ingestion of a provoking dose of sulfite. The reactions can be fairly severe on occasion and deaths own been attributed to sulfite-induced asthma (Bush and Taylor, ). The role of sulfites in the causation of asthma in susceptible individuals has been well documented by DBPCFC (Bush and Taylor, ; Stevenson and Simon, ). Other symptoms own also been alleged to happen as a result of sulfite sensitivity but these reports own been largely anecdotal and unverified by DBPCFC (Bush and Taylor, ).

Sulfite-induced asthma affects only a little percentage of every asthmatic individuals (Bush et al., ).

The prevalence among severe asthmatics who are dependent upon steroid-based drugs for control of their symptoms appears to be in the range of 4–7%, while mild asthmatics do not seem to be extremely susceptible to sulfite ingestion (Bush et al., ). Thus, the overall prevalence of sulfite-induced asthma is estimated at –% of the entire asthmatic population (Bush et al., ).

Sulfite-induced asthmatics display thresholds for sulfites (Bush and Taylor, ; Taylor et al., ).

While the ingestion of high doses of sulfite in highly sulfited foods and beverages can be fairly hazardous for susceptible individuals, the ingestion of sulfited foods with lower levels of residual sulfite (< ppm as entire SO2) seems to present little risk (Taylor et al., ). Thus, sulfite-sensitive asthmatics must be alert to the presence of sulfites in foods at levels that are required to be declared on the ingredient statement, but are at no risk from ingestion of sulfites from foods that own levels of residual sulfite under the detection limit of current assay procedures (<10 ppm as entire SO2).

The mechanism of sulfite-induced asthma is not known.

Several diverse mechanisms own been proposed including IgE-mediated reactions, hypersensitivity to inhaled SO2 from ingestion of acidic foods and beverages, and sulfite oxidase deficiency (Bush and Taylor, ). However, none of these mechanisms has been proven, so sulfite-induced asthma remains an idiosyncratic illness.

Implications for Food Manufacturing

Individuals with food allergy own an overreactive immune systemtowards aparticularfood.

Such a response happens due toan antibody calledIgE (Immunoglobulin E). Individuals suffering from food allergy often own a family history ofallergies.The most common food allergens are the proteins in cow’s milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

The symptoms on food allergy may not depend on the quantity of allergenic food consumed and may even happen with consumption of tiny amounts. It is also significant to note that numerous allergens may cause symptoms even after they own been cooked, and even after undergoing the digestive process.

On the other hand, some otherallergens, typically certain fruits and vegetables, may only cause allergies when consumed raw.

In some food groups, such as seafood andtree nuts, a phenomenon called cross-reactivity may be seen. This implies that if an individual has an allergy to onemember of a food family, they may also beallergic to other members of the same food group. Interestingly, cross-reactivitymay not be as commonly seen infoods from animal groups. For example, it has been found that individuals who may own allergiesto cow’s milk may still be capable toeat beef. Similarly, individuals with egg allergies may still be abletoeat chicken.

It has also been found thatamong shellfish, crustaceans (shrimp, crab and lobster) are most likely to cause an allergic reaction. Other mollusks such as clams, oysters and scallops are somewhat lesscommonly associated with allergies.

Symptoms of Food Allergies:
Symptoms of allergic reactions are commonly dermatological in nature and may causeskin itching, hives and swelling. Vomiting and diarrhea are common gastrointestinal symptoms. Symptoms of the respiratory system generally happen onlyin conjunction withskin and gastrointestinal symptoms.

Severe Allergic Reactions:
Anaphylaxis is a serious allergic reaction that happens extremely quickly and needs immediate and urgent attention!The symptoms often includedifficulty in breathing, loss of consciousness and dizziness.

If you noticeany of these symptoms,especially after eating, call rightaway. It is imperative to seek medical care immediately (call ). Don’t wait to see if your symptoms go away or get better on their own. Without immediate treatment and effective and expert medical care, anaphylaxis can be lethal. It is essential to follow up with your allergist in such cases.

Diagnosis:
An allergist is the best qualified professional to diagnose food allergy. Your allergist will take a thorough medical history, followed by a physical examination. You may be asked about contents of the foods, the frequency, seasonality, severity and nature of your symptoms and the quantity of time between eating a food and any reaction.

Allergy skin tests may determine which foods, if any, trigger your allergic symptoms.

In skin testing, a little quantity of extract made from the food is placed on the back or arm. If a raised bump or little hive develops within 20 minutes, it indicates a possible allergy. If it does not develop, the test is negative. It is unusual for someone with a negative skin test to own an IgE-mediated food allergy.

In certain cases, such as in patients with severe eczema, an allergy skin test cannot be done. Your doctor may recommend a blood test. Untrue positive results may happen with both skin and blood testing.

What is the most common food allergies

Food challenges are often required to confirm the diagnosis. Food challenges are done by consuming the food in a medical setting to determine if that food causes a reaction.

Another question that is commonly asked is whether children outgrow their food allergies. It has been reported that most children may outgrow  certain allergies such as those to soy, egg, cow’s milk, and wheat allergy, even if they own a history of a severe reaction. About 20% of children with peanut allergy will outgrow it. About 9% of children with tree nut allergy will outgrow it. Your allergist can assist you study when your kid might outgrow a food allergy.

Treatment:

The best way to treat food allergy is to avoid the foods that trigger your allergy.

Always check the ingredients when eating, especially when out of home. Carefully read labels that indicate food information.

Carefully read food labels. Always carry and know how to use injectable epinephrine and antihistamines to treat emergency reactions. Teach family members and other people shut to you how to use epinephrine! It is also significant to wear an ID bracelet that describes your allergy.

Food allergies can be confusing and isolating. For support, you may contact the Food Allergy & Anaphylaxis Network (FAAN) at ()

(Information only; not intended to replace medical advice; adapted from AAAAI)

Colonization with the Staphylococcus aureus bacterium was significantly and independently associated with food allergy in young children with eczema enrolled in a pivotal peanut allergy prevention study.

is a marker for severe eczema, and early eczema is a widely recognized risk factor for developing food allergies in young children.

But the findings from the Learning Early About Peanut Allergy (LEAP) study cohort show that even after controlling for eczema severity, skin S.

aureus positivity was associated with an increased risk for developing allergies to peanuts, eggs, and cow’s milk.

S. aureus colonization was also associated with persistent egg allergy until at least age 5 or 6 years in the LEAP cohort analysis in the Journal of Allergy and Clinical Immunology.

The lead researcher, Olympia Tsilochristou, MD, of Kings College London, said in a press statement that the findings could assist explain why young children with eczema own a extremely high risk for developing food allergies.

While the exact mechanisms linking the two are not known, «our results propose that the bacteria Staphylococcus aureus could be an significant factor contributing to this outcome,» she said.

The findings also propose that S. aureus colonization may inhibit peanut tolerance among at-risk infants when peanuts are introduced extremely early in life.

Among the nine participants in the peanut-consumption arm of the study (i.e., no peanut allergy at baseline) who had confirmed peanut allergy at 60 and 72 months, every but one were colonized with S.

aureus at one or more LEAP study visits.

«The fact that S. aureus was associated with greater risk of peanut allergy among peanut consumers but not peanut avoiders further suggests that peanut consumption was less effective in the prevention of peanut allergy among participants with S. aureus compared with those with no S. aureus,» the researchers wrote.

The LEAP study enrolled infants ages months with severe eczema, egg allergy, or both.

The babies were randomized to therapeutic peanut consumption or peanut avoidance, and every had eczema clinical evaluation and culture of skin and nasal swabs at baseline.

The follow-up LEAP-On study assessed the children at age 72 months, after 12 months of peanut avoidance in both groups.

Skin and nasal swabs were obtained at baseline and at age 12, 30, and 60 months. A entire of % of the participants had some form of S. aureus colonization (% skin and % nasal) on at least one LEAP study visit, with most having just one positive test result. The greatest rates of colonization were recorded at months of age.

S.

aureus colonization was significantly associated with eczema severity, along with hen’s egg white and peanut specific immunoglobulin (sIg)E production at any LEAP visit. But even after controlling for eczema severity, hen’s egg white and peanut sIgE levels at each LEAP and LEAP-On visit were significantly associated with skin S.

What is the most common food allergies

aureus positivity, the team noted.

«This relationship was even stronger when we looked into high-level hen’s egg white and peanut sIgE production,» the researchers wrote. «Similar findings were noted for cow’s milk, where high-level sIgE production to milk at 30, 60, and 72 months of age was related to any skin S. aureus colonization. Together, these data propose that S. aureus is associated with hen’s egg, peanut, and cow’s milk allergy.»

In the LEAP study, extremely early peanut consumption was found to reduce the risk of peanut allergy at 60 months in infants at high risk for developing the allergy, but infants in the consumption arm of the study with S.

aureus colonization were approximately seven and four times more likely to own confirmed peanut allergy at 60 and 72 months, the team said.

Study strengths, Tsilochristou and co-authors noted, included the rigorous design; a limitation was the reliance on bacteriological culture to identify S. aureus colonization rather than using DNA-based testing.

«S. aureus has been implicated in the development and severity of atopic diseases, namely eczema, allergic rhinitis, and asthma; our findings extend these observations to the development of food allergy independent of eczema severity,» the investigators concluded.

«The role of S. aureus as a potential environmental factor should be considered in future interventions aimed at inducing and maintaining tolerance to food allergens in eczematous infants.

Further prospective longitudinal studies measuring S. aureus with more advanced techniques and interventional studies eradicating S. aureus in early infancy will assist elucidate its role in the development of eczema or food allergy,» the team wrote.

Non-IgE Mediated Food Allergies

Most symptoms of non-IgE mediated food allergies involve the digestive tract. Symptoms may be vomiting and diarrhea.

The symptoms can take longer to develop and may final longer than IgE mediated allergy symptoms. Sometimes, a reaction to a food allergen occurs up 3 days after eating the food allergen.

When an allergic reaction occurs with this type of allergy, epinephrine is generally not needed. In general, the best way to treat these allergies is to stay away from the food that causes the reaction. Under are examples of conditions related to non-IgE mediated food allergies.

Not every children who react to a certain food own an allergy.

They may own food intolerance. Examples are lactose intolerance, gluten intolerance, sulfite sensitivity or dye sensitivity. Staying away from these foods is the best way to avoid a reaction. Your child’s doctor may propose other steps to prevent a reaction. If your kid has any food allergy symptoms, see your child’s doctor or allergist. Only a doctor can properly diagnose whether your kid has an IgE- or non-IgE food allergy.

Both can be present in some children.

Eosinophilic Esophagitis (EoE)

Eosinophilic (ee-uh-sin-uh-fil-ik) esophagitis is an inflamed esophagus. The esophagus is a tube from the throat to the stomach. An allergy to a food can cause this condition.

With EoE, swallowing food can be hard and painful. Symptoms in infants and toddlers are irritability, problems with eating and poor weight acquire. Older children may own reflux, vomiting, stomach pain, chest pain and a feeling love food is “stuck” in their throat.

The symptoms can happen days or even weeks after eating a food allergen.

EoE is treated by special diets that remove the foods that are causing the condition. Medication may also be used to reduce inflammation.

Food Protein-Induced Enterocolitis Syndrome (FPIES)

FPIES is another type of food allergy. It most often affects young infants. Symptoms generally don’t appear for two or more hours.

Symptoms include vomiting, which starts about 2 hours or later after eating the food causing the condition. This condition can also cause diarrhea and failure to acquire weight or height. Once the baby stops eating the food causing the allergy, the symptoms go away. Rarely, severe vomiting and diarrhea can happen which can lead to dehydration and even shock. Shock occurs when the body is not getting enough blood flow. Emergency treatment for severe symptoms must happen correct away at a hospital. The foods most likely to cause a reaction are dairy, soy, rice, oat, barley, green beans, peas, sweet potatoes, squash and poultry.

Allergic Proctocolitis

Allergic proctocolitis is an allergy to formula or breast milk.

This condition inflames the lower part of the intestine. It affects infants in their first year of life and generally ends by age 1 year.

The symptoms include blood-streaked, watery and mucus-filled stools. Infants may also develop green stools, diarrhea, vomiting, anemia (low blood count) and fussiness. When properly diagnosed, symptoms resolve once the offending food(s) are removed from the diet.

Medical review December

For Immediate Release Contact: Jo Ann Faber at () [email protected]

ARLINGTON HEIGHTS, Ill., July 24, Food allergy knowledge in the general public is poor concerning the difference between food allergy and food intolerance, the absence of a cure, and current treatments according to a report published this month in Annals of Allergy, Asthma & Immunology, the scientific journal of the American College of Allergy, Asthma and Immunology (ACAAI).

"The public s food allergy knowledge and awareness is critical to the safety of children with food allergy, especially since 76 percent of food allergy-related deaths follow consumption of foods exterior of the home.

Food allergy is a growing health concern, affecting an estimated 6 percent to 8 percent of children in the United States," said Ruchi S. Gupta, M.D., of the Mary Ann & J. Wilburn Smith Children Health Research Program at Children s Memorial Research Middle in Chicago.

In a national sample of 2, adults who completed the validated Web-based Chicago Food Allergy Research Survey for the General Public, Dr. Gupta and colleagues found "the public s knowledge was strongest regarding symptoms and severity of food allergy, with almost 95 percent of participants recognizing food allergy as a potentially fatal condition."

Among the misconceptions, investigators reported that "almost half of participants erroneously believed that a cure exists for food allergy, and more than two thirds stated that a daily medicine could be taken to prevent a food allergy reaction.

They also tended to overlook the necessity of strict allergen avoidance: more than 40 percent of participants indicated that other means exist to prevent life-threatening reactions."

Authors noted that almost 85 percent of respondents agreed that schools should own plans to hold food-allergic children safe.

"Although there was agreement that schools need better policies to manage food allergies, most parents were not in favor of implementation of specific school policies, such as banning peanut products and having special tables for food-allergic children," Dr.

Gupta said.

Investigators conclude that "increased food allergy knowledge among the general public is needed, especially regarding the distinction between food allergy and food intolerance, current treatments available for food allergy, the absence of a cure, and the lack of preventative medications."

"Although food allergy is a commonplace term, this study confirms the prevailing misconceptions among the public regarding manifestations, diagnosis, and treatment," said Sami L.

Bahna, M.D., Dr.P.H., professor of pediatrics & medicine, chief of Allergy & Immunology Section at Louisiana State University Health Sciences Middle in Shreveport, La., and president-elect of ACAAI. "Appropriate diagnosis is the cornerstone for appropriate management. Also, exclusion of food allergy would direct the search to other causes of the patient s illness. At present the treatment is basically strict avoidance of the causative foods.

Research is underway for effective and safe immunotherapy."

To the author s knowledge, "this study is the first to provide detailed information about the general public s food allergy knowledge and to characterize the general public s attitudes and beliefs toward food allergy and food allergy policy."

About Food Allergy

Current treatment of food allergy includes identification and strict avoidance of the offending food, and recognition of systems that can lead to anaphylaxis.

Anaphylaxis is the most severe form of allergic reactions, affecting multiple organ systems. Symptoms can include chest tightness, wheezing, nausea, vomiting, cramping, hives, and swelling of the lips and joints. The most dangerous symptoms are breathing difficulties, throat swelling, chest wheezing, dizziness, low blood pressure, shock and loss of consciousness, every of which can be fatal. Patients with severe reactions should own continued access to self-istered epinephrine injections.

The most common food allergens in infants and young children are cow s milk, hen s egg, peanut (a legume), tree nuts (walnut, hazelnut, Brazil nut, and pecan), soybeans and wheat.

Although sensitivity to most allergens is lost in tardy childhood, allergy to peanut, tree nut and seafood is likely to continue throughout the patient s life. Only approximately 20 percent of children with peanut allergy lose their sensitivity. The most common foods causing allergy in adults are peanuts, tree nuts, fish, crustaceans, mollusks, fruits and vegetables.

Patient information on allergic diseases including food allergy is available by visiting the ACAAI Web site at

About ACAAI

The American College of Allergy, Asthma and Immunology (ACAAI) is a professional medical organization headquartered in Arlington Heights, Ill., that promotes excellence in the practice of the subspecialty of allergy and immunology.

The College, comprising more than 5, allergists-immunologists and related health care professionals, fosters a culture of collaboration and congeniality in which its members work together and with others toward the common goals of patient care, education, advocacy and research.

###

Citation: Gupta RS,et al. Food allergy knowledge, attitudes, and beliefs in the United States. Ann Allergy Asthma Immunol ;

Annals of Allergy, Asthma & Immunology is online at

Centuries ago, Lucretius said that one man’s food may be another man’s poison.

Such is the case with food allergies. Individuals with food allergies and other types of food sensitivities react adversely to the ingestion of foods and food ingredients that most consumers can ingest with no problems.

Eating is necessary to sustain life. For most consumers, eating is an enjoyable experience given the variety and abundance of foods available in the marketplace. For some individuals, however, consuming certain foods can be a debilitating, possibly even life-threatening, experience.

Individuals with various forms of food allergies and sensitivities must avoid certain foods or food ingredients in their diets. For such people, the joy of eating is diminished by the ever-present concern that they might consume a food or food ingredient that will elicit an adverse reaction. For them, food selection can become a tedious task requiring the painstaking reading of ingredient lists on the labels of packaged foods and a ceaseless search for more knowledge about food composition. Food preparation requires careful attention to details such as “cooking from scratch,” seeking alternative recipes for numerous dishes, and avoidance of shared utensils, containers, and cooking surfaces between allergenic and non-allergenic foods.

In situations where one family member has a extremely serious allergic sensitivity, the entire family often has to avoid the offending food as a precautionary measure.

Definitions
Food allergies and other food sensitivities are individualistic adverse reactions to foods (Taylor, ). These food-related illnesses are individualistic because they affect only a few people in the population; most consumers can eat the same foods with no ill effects. Numerous diverse types of reactions are involved in these individualistic adverse reactions to foods (Fig.

1; Anderson, ; Taylor, ). Adverse food reactions can include IgE and non-IgE-mediated primary immunological sensitivities, non-immunological food intolerances, and secondary sensitivities. While these various types of reactions are often considered collectively as food allergies, true food allergies represent only a part of the individualistic adverse reactions to foods.

True Food Allergies. True food allergies are abnormal (heightened) responses of the immune system to components of certain foods (Lemke and Taylor, ). The components of foods that elicit these abnormal immune responses are typically naturally-occurring proteins in the foods (Bush and Hefle, ).

True food allergies can be divided into two categories based upon the nature of the immune response—immediate hypersensitivity reactions and delayed hypersensitivity reactions (Lemke and Taylor, ). In immediate hypersensitivity reactions, symptoms start to develop within minutes to an hour or so after ingestion of the offending food. Immediate hypersensitivity reactions own been noted with numerous foods and can sometimes be fairly severe (Hefle et al., ). Immediate hypersensitivity reactions involve abnormal responses of the humoral immune system with the formation of allergen-specific immunoglobulin E (IgE) antibodies (Mekori, ).

In delayed hypersensitivity reactions, symptoms do not start to appear until 24 hours or longer after the ingestion of the offending food (Lemke and Taylor, ). With the exception of celiac disease, which involves an abnormal immunological response to wheat and related grains (Ferguson, ), the role of delayed hypersensitivity reactions to foods remains poorly defined. Delayed hypersensitivity reactions involve abnormal responses of the cellular immune system with the development of sensitized T cells (Lemke and Taylor, ).

Allergy-Like Intoxications.

Certain foods can elicit adverse reactions that resemble true food allergies. These foods contain elevated levels of histamine, one of the principal mediators of allergic reactions in the body (Taylor et al., a). In true food allergies and anaphylactoid reactions, however, histamine is released from intracellular locations (Mekori, ). In these allergy-like intoxications, histamine is ingested with foods. Histamine poisoning is often known as scombroid fish poisoning because it is frequently associated with consumption of spoiled fish of the scombroid type such as tuna and mackerel (Taylor et al., a).

However, histamine poisoning can also happen from the ingestion of spoiled fish such as mahi-mahi and bluefish that are not scombroid fishes (Etkind et al., ; Taylor et al., a). And, histamine poisoning has even been occasionally associated with the ingestion of cheese, especially aged Swiss cheese (Stratton et al., ; Taylor et al., ). In every of these food products, specific types of bacteria own proliferated and caused the conversion of the amino acid, histidine, into histamine (Stratton and Taylor, ; Sumner et al., ; Taylor et al., ). Ingestion of little amounts of histamine in the diet is a normal occurrence and does not cause any harm.

However, when large doses of histamine are ingested with foods, the body’s protective mechanisms can be overwhelmed resulting in histamine poisoning (Taylor, ). Unlike food allergies and sensitivities, every consumers are susceptible to histamine poisoning. Because this illness is not truly a form of food allergy or sensitivity, it will not be discussed further. It does merit some mention because the similarity in symptoms can cause it to be confused with true food allergy.

Sheet BREAK

Food Intolerances. Food intolerances are abnormal reactions to foods or food components that do not involve the immune system.

Several diverse types of food intolerances are also known to exist. These intolerances are metabolic food disorders, anaphylactoid reactions, and idiosyncratic reactions (Taylor, ). Metabolic food disorders are adverse reactions to a food or food component that results from a defect in the metabolism of these foods or some substance therein or from an affect of the food or food component on the body’s normal metabolic processes. Lactose intolerance is an example of a metabolic food disorder resulting from a defect in the metabolism of a food component (Kocian, ). Favism is an example of a metabolic food disorder resulting from foodborne substances that interfere with normal metabolic processes (Mager et al., ).

Anaphylactoid reactions are adverse reactions resulting from the ingestion of foodborne substances that release histamine from cellular stores within the body (Taylor, ). There are no particularly excellent examples of anaphylactoid reactions, although circumstantial evidence suggests that such reactions may happen. Food idiosyncrasies are adverse reactions to foods or food components that happen through unknown mechanisms and which can even include psychosomatic illnesses (Taylor, ). Sulfite-induced asthma is the best example of an idiosyncratic reaction that has been well documented to happen among certain consumers, although the mechanism remains unknown (Bush and Taylor, ).

Secondary Food Sensitivities. Adverse reactions to foods or food components can happen with or after the effects of other conditions. Examples of such reactions, termed secondary food sensitivities, include lactose intolerance secondary to gastrointestinal disorders such as Crohn’s disease or ulcerative colitis (Metcalfe, a) and drug-induced sensitivities such as the increased sensitivity to tyramine among patients on monoamine oxidase-inhibiting drugs (Blackwell and Marley, ).

IgE-Mediated Food Allergies
This type of food allergy can also be called immediate hypersensitivity, Type I allergy, or food anaphylaxis.

The Greek expression, anaphylaxis, means “against protection” and refers to allergic reactions to foreign protein molecules. IgE is one of five classes of antibodies that are present in the human body and that frolic a role in disease resistance. IgE antibodies are particularly involved in fighting off parasitic infections. Although every humans own low levels of IgE antibodies, only individuals predisposed to the development of allergies produce IgE antibodies that are specific for and recognize certain environmental antigens. These antigens are typically proteins, although only a few of the numerous proteins in nature are capable of stimulating the production of specific IgE antibodies in susceptible individuals (Taylor, ).

The allergens eliciting IgE antibody formation can be found in pollens, mold spores, bee venoms, dust mites, and animal danders in addition to foods (Solomon and Platts-Mills, ).

Pathogenesis. The mechanism of IgE-mediated allergic reactions is depicted in Fig. 2. First, sensitization by the allergen must happen. In the sensitization phase of the response, the allergen stimulates production of specific IgE antibodies. While sensitization can happen with the first exposure to the allergen, that is not always the case. With honor to food allergens, sensitization does happen most commonly among young infants where the immune response seems to be more likely to be oriented toward an IgE response (Anderson, ).

However, even in susceptible infants exposure to most dietary proteins results in oral tolerance, a normal immunologic response that is not associated with adverse reactions, rather than sensitization (Strobel, ). The specific IgE antibodies then attach to mast cells in various tissues and basophils in the blood. Mast cells and basophils contain granules that are loaded with physiologically athletic chemicals that mediate the allergic response (Church et al., ). On subsequent exposure to the allergenic substance, the allergen cross-links two IgE antibodies on the surface of the mast cell or basophil membrane, stimulating the release into tissues and blood of a host of allergic response mediators.

Although numerous mediators own been described, histamine is one of the primary mediators responsible for numerous of the immediate symptoms that happen in IgE-mediated allergic reactions (Simons, ). Other significant mediators include the various leukotrienes and prostaglandins, some of which are associated with more delayed symptoms that can happen in IgE-mediated, immediate hypersensitivity reactions, the so-called late-phase responses (Peters et al., ).

Sheet BREAK

Symptoms. IgE-mediated food allergies are associated with a wide variety of symptoms, ranging from mild and annoying to severe and life-threatening (Lemke and Taylor, ).

The symptoms can involve the gastrointestinal tract, skin, or respiratory tract (Table 1). Food-allergic individuals generally suffer from only a few of the numerous possible symptoms. The nature and severity of the symptoms experienced by a food-allergic individual may also vary from one episode to the next depending on the dose of the offending food that has been inadvertently ingested, the degree of sensitization to the offending food at the time of the episode, and probably other factors. Because foods are ingested, gastrointestinal symptoms are often encountered (Anderson, ; Gryboski, ). However, these symptoms can also be involved in other illnesses so their association with food allergies is often hard to decipher.

Cutaneous symptoms such as urticaria (hives) and dermatitis (eczema) are also common manifestations of food allergies (Kaplan, ). These symptoms are more definitive for food allergy, although the frequency of dermatitis as a manifestation of food allergy especially, in infants, has only been widely appreciated in the past decade or so (Sampson, ). Respiratory symptoms are less commonly associated with food allergies than with environmental allergies such as pollen or animal dander allergies (Taylor et al., ). With environmental allergies, the allergens are inhaled, so the primary involvement of respiratory symptoms is understandable.

However, ingested food allergens must survive digestive processes and be absorbed to elicit systemic reactions in the respiratory tract. Although few asthmatic individuals experience food-induced asthma, asthma is among the most severe symptoms associated with food allergies (Bousquet and Michel, ). Food-induced asthma is a risk factor for severe, life-threatening reactions to the offending foods (Sampson et al., ).

Oral allergy syndrome is perhaps the most common manifestation of food allergy (Ortolani et al., ). Oral allergy syndrome is often so mild that it is ignored by afflicted individuals.

Oral allergy syndrome involves symptoms confined to the oropharyngeal area including hives, itching, and swelling (Pastorello and Ortolani, ). Unused fruits and vegetables are the foods most frequently associated with oral allergy syndrome (Pastorello and Ortolani, ). Individuals with oral allergy syndrome are generally sensitized to one or more pollens, and react to proteins in specific unused fruits and vegetables that cross-react with the pollen allergens (Calkoven et al., ; Ebner et al., ; van Ree and Aalberse, ).

Examples would include allergic reactions to watermelons and other melons in ragweed-allergic individuals (Enberg et al., ), allergic reactions to celery in mugwort-allergic or birch-sensitized individuals (Ballmer-Weber et al., ; Wuthrich et al., ), and allergic reactions to apples and hazelnuts in birch-allergic individuals (Dreborg, ). Because the allergens in these foods are inactivated on contact with stomach acid and digestive proteases, systemic reactions to these unused fruits and vegetables are rarely encountered (Taylor and Lehrer, ).

Because these allergens are denatured by heating (Dreborg and Foucard, ; Taylor and Lehrer, ), individuals with oral allergy syndrome can generally safely ingest heat-processed forms of the offending food, e.g., apple jelly or apple sauce. Recent evidence indicates that, in contrast to previous assumptions, some individuals with oral allergy syndrome associated with certain foods, such as celery, also may experience more severe systemic reactions on occasion (Ballmer-Weber et al., ).

The most frightening symptom associated with food allergies is anaphylactic shock, which generally involves multiple systems including the gastrointestinal tract, the skin, the respiratory tract, and the cardiovascular system.

Symptoms happen in combination and develop rapidly. Severe hypotension can happen. Death can happen from cardiovascular and/or respiratory collapse within minutes of ingestion of the offending food. Only a few of the numerous people with IgE-mediated food allergies are at risk for such serious manifestations. However, numerous deaths own been attributed to inadvertent exposure to the offending food among individuals with food allergies (Bock et al., ; Sampson et al., ; Yunginger et al., ).

These deaths own involved asthma and/or anaphylactic shock.

In addition to allergic reactions associated with the consumption of foods, occupational food allergies including occupational asthma, hypersensitivity pneumonitis (extrinsic alveolitis), and contact dermatitis can happen amongst food industry employees (O’Neil and Lehrer, ). Such reactions can be triggered in food manufacturing workers by food-derived protein allergens, e.g., green coffee beans, flour, and shellfish, or non-food agents, e.g., honey bees and latex products (Lehrer and O’Neil, ). These occupational allergies are produced by respiratory exposure to dusty processing environments or cutaneous exposure to specific food products.

Sheet BREAK

Diagnosis.

With the wide range of symptoms that can be involved in IgE-mediated food allergies and the possibility of other causes for numerous of these symptoms, the diagnosis of IgE-mediated food allergies can sometimes be challenging (Metcalfe, b). First and foremost, an association must be sought between the ingestion of one or more offending foods and the elicitation of the adverse reaction. Once a food-associated adverse reaction is well documented, then proof of the existence of an IgE mechanism must be considered. The assistance of an allergist should be sought in the diagnosis of IgE-mediated food allergies. Too often, consumers rely upon self-diagnosis or parental diagnosis.

Self-diagnosis and parental diagnosis of reactions in children are problematic because they are often erroneous, leading to the identification of the incorrect foods, and implicate too numerous foods (Bock et al., ). Careful history-taking including the use of food diaries by an experienced allergist can often identify suspect foods. Elimination diets followed by challenges can sometimes confirm the existence of a food-associated adverse reaction.

However, the gold standard for documenting existence of a food-associated adverse reaction is the double-blind, placebo-controlled food challenge (DBPCFC; Bock et al., ). Such clinical challenges are especially useful in situations where the role of a specific food remains somewhat questionable. Double-blind, placebo-controlled food challenges are not generally done in cases involving serious, life-threatening adverse reactions because of the obvious risks to the patient and the likelihood in such cases that the role of one or more specific foods is rather clear.

Once the role of one or more specific foods in the adverse reaction has been established, then the involvement of the IgE mechanism can be documented through skin-prick tests using extracts of the suspect foods (Bock et al., ) or by radioallergosorbent tests (RASTs) where the presence of food-specific IgE antibodies in the blood serum is examined (Adolphson et al., ).

Prevalence. IgE-mediated food allergies likely affect between 2 and % of the entire population. For numerous years, the overall prevalence estimate for IgE-mediated food allergies has been between 1 and 2% of the entire population (Lemke and Taylor, ).

However, a recent random, digit-dial telephone survey in the U.S. indicated that the combined prevalence of peanut and tree nut allergies was an estimated % (Sicherer et al., ). And, a similar telephone survey in the United Kingdom indicated that the estimated prevalence of peanut allergy alone was % (Emmett et al., ). While one could criticize the use of telephone surveys, it is unlikely that numerous consumers would mis-diagnose peanut or tree nut allergies since the symptoms are profound and generally fairly immediate.

Thus, these surveys may be reasonably dependable and a excellent indication that previous estimates based solely on clinical impression were incorrect. Certainly, if peanut and tree nut allergy alone account for more than 1% of IgE-mediated food allergy, then the overall prevalence of food allergy in the entire population likely exceeds 2%.

Infants (1–3 years of age) and children are more commonly affected by food allergies than other age groups (Taylor et al., ). Among infants younger than 3 years, the prevalence of food allergies appears to be in the range of 5% to 8% (Sampson, ). The prevalence of food allergy among young infants (<1 year of age) has been studied more thoroughly than has the prevalence among older children and adults.

A much higher proportion of the public believes that they own food allergies because of self-diagnosis, parental diagnosis, and misconceptions about the definition of food allergy even among some physicians (Bock et al., ; Sloan, ).

Studies own shown that 10 to 20% of the consuming public believes that they or someone in their family has a food allergy (Chiaramonte et al., ; Sloan, ).

Some believe, on the basis of the impressions of clinicians involved in allergy practice for several decades, that the prevalence of IgE-mediated food allergies is increasing. An increase in prevalence, however, is hard to confirm because excellent baseline data from earlier years for comparative purposes are lacking. Certainly, the awareness of food allergy has increased. More individuals may seek specialized medical attention from allergists as a result of this increased awareness. But, almost everyone agrees that the prevalence of severe food allergies seems to be increasing.

The reasons for this apparent increase are unknown. Numerous severely affected individuals own food-induced asthma as one of the manifestations of their allergic reaction. The overall prevalence of asthma is definitely increasing in the U.S. for unknown reasons (Beasley et al., ). While food-induced asthma is a little part of the entire asthma population, the prevalence of food-induced asthma may be increasing in concert with the overall increase in prevalence of asthma.

Most Common Allergenic Foods.
The prevalence of allergies to specific foods is not precisely known. Cows’ milk allergy appears to be among the more prevalent food allergies in infants.

This is not surprising given the importance of milk in baby feeding practices. The prevalence of cows’ milk allergy among infants under the age of two in Sweden, Denmark, and Australia has been studied and found to be approximately 2% in every three countries in well-conducted clinical studies involving groups of unselected infants followed from birth to the age of two years (Hill et al., ; Host and Halken, ; Jakobsson and Lindberg, ). The prevalence of milk allergy is known to decrease with age (Bock, ), but the exact prevalence of milk allergy among other age groups is unknown.

The prevalence of other specific food allergies has not been established in controlled clinical trials using unselected population groups. The comparative prevalence of various specific food allergies can be discerned from studies involving groups of individuals with probable food allergies. In the U.S., eggs and peanuts are also common allergenic foods for infants, along with soybeans, tree nuts, fish, and wheat (Bock and Atkins, ; Burks et al., ; Sampson and McCaskill, ). Among adults in the U.S., peanuts are probably the most common allergenic food (Taylor et al., ). Seafood allergies, especially to crustaceans (shrimp, crab, lobster), are also rather common among adults (Lehrer et al., ).

Fewer studies own been conducted on the prevalence of specific types of food allergies in adults in the U.S. or other countries. The prevalence of specific types of food allergies may vary among population groups based upon their eating habits (Taylor et al., ). Peanut allergy appears to be more common in North America than in other parts of the world. This observation may relate to the popularity of peanut butter in North America. As other countries, such as the United Kingdom, own adopted the North American affection for peanuts and peanut products, the prevalence of peanut allergy in those countries appears to be rising (Emmett et al., ).

Another example would be buckwheat allergy. Buckwheat allergy appears to be rather common among adults in certain southeast Asian countries such as Japan and South Korea (Kang and Min, ). In contrast, buckwheat allergy would be rather unusual in the U.S. The difference is likely due to the popularity of buckwheat noodles in the cuisine of certain southeast Asian countries. Such observations own profound implications for product developers. If a highly successful buckwheat product was introduced into the U.S. or if buckwheat noodles became favorite in American Asian cuisine, the prevalence of buckwheat allergy would likely increase.

Sheet BREAK

The Large Eight.

Eight foods or food groups are thought to account for more than 90% of every IgE-mediated food allergies on a worldwide basis (Bousquet et al., ; FAO, ). These foods or food groups are milk, eggs, fish (all species of finfish), crustacea (shrimp, crab, lobster, crayfish), peanuts, soybeans, tree nuts (almonds, walnuts, pecans, cashews, Brazil nuts, pistachios, hazelnuts also known as filberts, pine nuts also known as pinyon nuts, macadamia nuts, chestnuts, and hickory nuts), and wheat. In , an expert consultation of the Food and Agriculture Organization of the United Nations sure that these eight foods or food groups were the most common causes of food allergy on a worldwide basis (FAO, ).

Subsequently this list was adopted by the Codex Alimentarius Commission in (CAC, ). These foods and food groups own come to be known as the “Big Eight” (Table 2). More than other foods own been documented as causing food allergies less frequently (Hefle et al., ).

Basically, any food that has protein has the potential to elicit an allergic reaction among susceptible individuals. Beyond the Large Eight, in certain geographic regions other foods or food groups may frequently cause IgE-mediated food allergies. Celery allergy, for example, is rather common in some European countries (Wuthrich et al., ).

The prevalence of buckwheat allergy in southeast Asia has already been mentioned. And, sesame seed allergy is extremely common in middle Eastern countries and countries where the ethnic population of middle Easterners is high; this may be due to the popularity of tahini, a paste made from sesame seeds, in the diets (Kanny et al., ). Several countries including Canada own decided to add sesame seeds to the list of commonly allergenic foods for that country. A few other foods are worthy of mention because, although they less frequently cause allergies, they own been associated with severe reactions. These foods include molluscan shellfish (clams, oysters, etc.), sesame seeds, poppy seeds, sunflower seeds, cottonseed, and certain other legumes beyond peanuts and soybeans (the various types of dry beans, peas, lentils, and garbanzo beans also known as chick peas) (Atkins et al., ; Gall et al., ; Kagi and Wutrich, ; Kalyoncu and Stalenheim, ; Kanny et al., ; Maeda et al., ; Martin et al., ; Noyes et al., ).

However, a rather large percentage of the or more other allergenic foods has been reported to elicit severe allergic reactions in isolated cases (Hefle et al., ).

Food Allergens. The allergens in foods are almost always naturally occurring proteins. Foods contain millions of individual proteins, but only a comparative few of the proteins own been documented to be allergens (Bush and Hefle, ; Taylor, ). Some foods such as milk, eggs, and peanuts are known to contain multiple allergenic proteins (Bush and Hefle, ). Other foods such as Brazil nuts, shrimp, and codfish contain only one major allergenic protein (Bush and Hefle, ). However, the majority of the proteins, even those from commonly allergenic foods, are incapable of eliciting IgE production.

Although the common allergenic foods listed above tend to be excellent sources of protein, other common protein-rich foods such as beef, pork, chicken, and turkey are rarely allergenic. No common structural features own allowed distinctions to be made between those proteins that are capable of eliciting IgE production and those that are not. Allergenic proteins, however, tend to be major proteins in the implicated foods, resistant to digestion, and stable to processing operations, particularly heat processing (Taylor and Lehrer, ).

Development of IgE-Mediated Food Allergies.

Genetics frolic an significant role in the development of IgE-mediated allergies of every types, including food allergies (Kjellman and Bjorksten, ). Allergies are much more likely to develop in children born to parents who own allergies (either to food, pharmaceutical, or environmental allergens) than amongst children born to parents with no history of allergies (Taylor et al., ). However, the nature of the allergy that develops is not genetically controlled. Therefore, the children of pollen-allergic parents are at increased risk for development of food allergies as are the children of food-allergic parents. The risk is greater if both parents own allergies than it is if only one parent has allergies.

Infants are the most likely to develop food allergies (Sampson, ; Taylor, ).

However, sensitization to foods can happen at any age. Infants do not appear to develop allergies in utero (Kjellman and Bjorksten, ), but can be sensitized during the first few days of life. Obviously, the newborn baby encounters through the first few years of life dozens of new foods and probably hundreds of thousands of food proteins that own antigenic and possibly allergenic potential. For most of these foods and their proteins, infants develop oral tolerance (Strobel, ). Infants appear to be at increased risk for the development of IgE-mediated food allergies in part because their digestive processes may not be fully developed but primarily because they own not yet had the chance to develop oral tolerance.

Certain foodborne proteins seem to be much more likely than others to cause allergic sensitization (Bush and Hefle, ). The factors involved in sensitization and the development of IgE-mediated food allergies are not yet fully understood.

Sheet BREAK

Prevention of IgE-Mediated Food Allergies. The prevention of the development of IgE-mediated food allergies among high-risk infants (those born to parents with histories of allergies) has been a long-sought goal. However, the results of several large clinical trials of high-risk infants followed for several years propose that the development of IgE-mediated food allergies can be delayed but not prevented (Zeiger and Heller, ).

The maternal diet during pregnancy does not seem to be a factor (Zeiger and Heller, ), because sensitization does not happen in utero. The avoidance of commonly allergenic foods such as cows’ milk, eggs, and peanuts in the baby diet during the first few years of life often delays the development of food allergies, but food allergies may still develop after solid foods are introduced (Hattevig et al., ; Zeiger and Heller, ). Avoidance can be accomplished through breast-feeding or the feeding of hypoallergenic baby formula (Kjellman and Bjorksten, ; Zeiger and Heller, ).

Numerous pediatricians recommend breast-feeding for infants born to parents with histories of IgE-mediated allergies. Lactating women can apparently transmit potentially sensitizing levels of food allergens through their milk to nursing infants (Van Asperen et al., ). Apparently, intact or partially intact allergenic proteins are capable to survive maternal digestive processes and be absorbed via the lymph and transferred immunologically intact into breast milk (Van Asperen et al., ). Infants own been sensitized through breast-feeding to peanuts, cows’ milk, and eggs (Van Asperen et al., ).

The avoidance of peanuts in the maternal diet during the lactation period is often advocated as a preventive measure. However, the exclusion of milk and eggs from the maternal diet during lactation is not generally recommended due to their nutritional importance coupled with the low likelihood of allergic sensitization through breast-milk (Taylor et al., ). The use of hypoallergenic baby formula to prevent or delay the development of IgE-mediated food allergies is less commonly practiced. However, the use of partial whey hydrolysate formulae for this purpose may show some promise (Vandenplas et al., ), although such partial hydrolysates are not safe for consumption by infants who are already sensitized to cows’ milk (Businco et al., ; Ellis et al., ).

Apparently, the partial hydrolysis of the whey proteins increases the likelihood of the development of oral tolerance as opposed to allergic sensitization.

Natural History of IgE-Mediated Food Allergies. Most food allergies developed in infancy are outgrown in infancy or early childhood. Numerous infants outgrow their food allergies, often within a matter of a few months (Bock, ; Hill and Hosking, ).

Allergies to certain foods such as cows’ milk, eggs, and soybeans are much more likely to be outgrown than allergies to other foods such as peanuts (Bock, ; Bock and Atkins, ). Peanut allergy is almost never outgrown. The loss of allergic sensitivity to a specific food probably results from the development of immunological, oral tolerance (Taylor et al., a). However, the basis for the differences between specific foods (e.g., milk vs. peanuts) in the development of oral tolerance is not understood.

Cross-Reactions between Related Allergenic Foods. Allergic consumers sometimes experience cross-reactions between closely related foods.

For example, with the crustacea, most sensitive individuals are allergic to every of the various species of shrimp, crab, lobster, and crayfish (Lehrer, ). However, these individuals can often eat other seafoods including finfish and molluscan shellfish. Similar cross-reactivity also exists between cows’ milk and goats’ milk (Bellioni-Businco et al., ) and between eggs of various avian species (Langeland, ). With other food groups, the situation can be fairly complicated.

What is the most common food allergies

For example, peanuts are the most commonly allergenic legumes. Most peanut-allergic individuals can eat other legumes without incident (Bernhisel- Broadbent and Sampson, ). A few peanut-allergic individuals are also allergic to soybeans (Herian et al., ), although this may not necessarily represent true cross-reactivity. With fish, individuals often experience reactions to more than one species of fish, but some fish are tolerated by some fish-allergic individuals and no definite patterns of reactivity own been identified (Bernhisel-Broadbent et al., ; de Martino et al., ).

Cross-Reactions between Food and Environmental Allergens.

Cross-reactions are frequently observed between pollens and certain foods, especially fruits and vegetables (Ballmer-Weber et al., ; Calkoven et al., ; van Ree and Aalberse, ; Wuthrich et al., ). This is the oral allergy syndrome, which typically involves mild reactions as previously mentioned. Examples include cross-reactions between birch pollen and apples, ragweed pollen and melons, and mugwort pollen and celery (Ballmer-Weber et al., ; Calkoven et al., ; Enberg et al., ; van Ree and Alberse, ; Wuthrich et al., ). Cross-reactions own also been noted between latex allergies, a common problem among health-care workers, and certain foods including bananas, kiwis, avocados, and chestnuts (Blanco et al., ).

Effect of Food Processing on Allergens.

As mentioned earlier, the allergens in foods are typically proteins that are stable to heat processing (Taylor and Lehrer, ). So, heat-processed forms of commonly allergenic foods often retain their allergenicity (Herian et al., ; Nordlee et al., ). The only exception would be the pollen-related allergens found in unused fruits and vegetables and involved in oral allergy syndrome; these allergens are generally destroyed by heat processing (Dreborg and Foucard, ), although the necessary extent of the heat process has not been well documented in most cases.

For the most common allergenic foods, every forms of those foods should be considered allergenic unless proven otherwise. Testing has indicated that most forms of peanuts and soybeans, for example, retain their allergenicity (Herian et al., ; Nordlee et al., ). Other processing techniques own not been so well investigated for their effects on the allergenicity of the resulting products. Since allergens are resistant to proteolysis, fermentation generally fails to eliminate allergenicity (Taylor and Lehrer, ).

For example, although fermented soybean products are reduced in allergenicity, some allergenic activity is retained (Herian et al., ).

Sheet BREAK

If the protein part is removed during processing, however, the resulting product or ingredient might be safe because the allergen has been removed. The classic example is the processing of edible oils from peanuts and soybeans (Bush et al., ; Hourihane et al., a; Taylor et al., ). Clinical challenge trials in peanut- and soybean-allergic individuals own documented that highly refined peanut and soybean oil are safe for individuals with allergies to the source material (Bush et al., ; Hourihane et al., a; Taylor et al., ).

Other ingredients may be derived from allergenic sources.

Examples include certain flavoring formulations, starch, lecithin, and gelatin. Flavors can occasionally contain protein residues from allergenic foods (Taylor and Dormedy, ). Starch is often made from corn or some other source that is rarely allergenic. Occasionally, starch is made from wheat, although the level of protein residues is fairly low and adverse reactions to wheat starch own not been reported. Lecithin can be made from either soybean or egg and can contain allergenic residues (Muller et al., ). However, the degree of risk posed by the low residual levels of soybean allergens in lecithin remains unknown.

Gelatin is most commonly made from beef and pork, foods that are rarely allergenic (Sakaguchi et al., ). However, gelatin can also be made from fish skins. The allergenicity of fish gelatin remains unknown (Sakaguchi et al., ).

Treatment. Allergic reactions to foods can be treated with certain drugs (Furukawa, ; Simons, ). Antihistamines can counteract the effects of histamine (Simons, ), although these drugs do not counteract the effects of the other mediators released from basophils and mast cells.

Epinephrine (adrenaline) is considered the life-saving drug for individuals at risk of severe anaphylactic shock-type reactions to foods (Sampson et al., ). Epinephrine is available in self-injectable form. Consumers with a history of severe anaphylactic reactions to foods should own a prescription for epinephrine and carry the medication at every times. To be most effective, epinephrine must be istered early in the course of the allergic reaction.

What is the most common food allergies

However, an examination of severe food-allergic reactions resulting in deaths or near-deaths reveals a delay in the istration of epinephrine as a key contributing factor to the severe outcome (Sampson et al., ).

The specific avoidance diet is the only prophylactic approach to the treatment of food allergies (Taylor et al., a; Taylor et al., ). For example, individuals allergic to peanuts must simply avoid ingesting peanuts. The construction of safe and effective avoidance diets is often a challenge for individuals with food allergies. With packaged foods, these individuals must spend considerable time in the scrutiny of ingredient declarations on product labels.

They must be taught to recognize the numerous terms that may signify the presence of food components or ingredients derived from their offending food(s). Some foods, especially in foodservice settings, are sold without ingredient statements. Clearly, the allergic consumer can encounter numerous hazardous situations in such circumstances and must be trained to be extremely vigilant. Also, exposure to extremely little amounts of the offending food may be sufficient to elicit allergic reactions in some sensitive individuals, further complicating the necessary vigilance in the implementation of effective avoidance diets.

Threshold Doses for Allergenic Foods.

As noted, individuals with IgE-mediated food allergies will experience symptoms on exposure to little amounts of the offending food. The interaction of a little quantity of the allergen with specific IgE antibodies on the surface of the mast cell or basophil membrane triggers the release of massive quantities of mediators, which accounts for the low degree of threshold. The precise threshold doses for allergenic foods own not been carefully investigated and are likely to be variable from one allergic individual to another. In a recent study, Hourihane et al.

(b) demonstrated that a group of individuals with peanut allergy displayed diverse thresholds for peanuts. The most sensitive individual among 12 tested subjects experienced an objective reaction when exposed to 2 mg of peanut protein. Other patients in the group did not even reply to the highest dose used in the challenge trial which was 50 mg of peanut protein. While this experiment clearly demonstrates that the threshold level is not zero, the threshold dose is fairly low.

Whether other allergenic foods own thresholds as low as those for peanuts remains to be determined.

Allergenicity of Foods Produced Through Agricultural Biotechnology. In the genetic modification of foods, genes are transferred from one organism to another. Because these genes code for the expression of a specific protein, novel proteins are expressed in the transgenic variety as a result. Because every allergens are proteins, the theoretical possibility exists that these novel proteins might be allergenic or that they might become allergenic.

However, only a few of the numerous proteins found in nature are allergenic, so the probability of the transfer of an allergen is rather low. The potential allergenicity of the novel proteins expressed in the new varieties produced through agricultural biotechnology should be assessed in every case.

Sheet BREAK

The potential allergenicity of the novel proteins in transgenic varieties can be assessed (FAO/WHO, ; Metcalfe et al., ; Taylor and Hefle, a). If a gene is transferred from a known allergenic source, the potential allergenicity of the expressed novel protein can be assessed with reasonable certainty by evaluating its reactivity by specific serum screening with serum containing IgE antibodies from individuals with well documented allergies to the source material.

This assessment approach was demonstrated to be effective when it was sure that a Brazil nut protein transferred into soybeans to correct the inherent methionine deficiency of soybeans was the heretofore unidentified major allergen from Brazil nuts (Nordlee et al., ). The company involved abandoned further commercial interest in these transgenic soybeans as a result. It should be emphasized that genes are not often obtained from known allergenic sources in the development of commercial transgenic varieties.

However, when genes are transferred from known allergenic sources, it must be assumed that the gene encodes for an allergenic protein unless proven otherwise.

More typically, genes are obtained from sources with no history of allergenicity. In these situations, a decision-tree approach is advocated for the assessment of the potential allergenicity of the novel protein. While no single test can perfectly predict the potential allergenicity of a specific novel protein from a source with no history of allergenicity, the application of a series of tests provides reasonable assurance that the novel protein is not likely to become an allergen. Several decision-tree approaches own been developed (FAO/WHO, ; Metcalfe et al., ; Taylor and Hefle, a).

These approaches rely upon evaluation of the source of the gene and its history of allergenicity, the sequence homology of the novel protein to known allergens, the immunoreactivity of the novel protein with serum IgE from individuals with known allergies to the source of the transferred gene, the immunoreactivity of the serum IgE from individuals with known allergies to sources that are broadly related to the source of the novel gene (e.g., grass pollen allergic individuals in cases where the gene is obtained from monocot sources), the pepsin resistance or digestive stability of the novel protein, and the immunogenicity of the novel protein in validated animal models (Fig.

3). Other factors especially the level of expression of the novel protein in the food are also likely to be significant since allergies are generally elicited by food proteins where dietary exposure is comparatively high.

Foods produced through agricultural biotechnology including corn, soybeans, canola, and potatoes are already reaching the consumer marketplace. The potential allergenicity of the novel proteins expressed in these commercial products has been assessed using the approaches indicated above. The novel proteins in these approved transgenic varieties are not obtained from known allergenic sources, are not structurally homologous to known food or environmental allergens, and are sensitive to digestive proteolysis.

Furthermore, the novel proteins are expressed at extremely low levels in the edible portions of these modified crops. Thus, the likelihood of allergenicity from this current generation of crops produced by agricultural biotechnology is virtually nil.

Considerable publicity has surrounded one specific transgenic variety, the so-called StarLink™ corn. StarLink corn was never approved for human use, but was unfortunately approved for animal feed use. When segregation failed, some StarLink corn residues were found in corn-based food products intended for human consumption.

Although the gene inserted in StarLink corn was obtained from a source with no history of allergenicity and the novel protein was not structurally similar to known food or environmental allergens, the novel protein was comparatively more resistant to digestive proteolysis than other novel proteins that had been approved for other genetically modified crops. For this reason, StarLink corn was never approved for human consumption. However, given the extremely low level of exposure to the novel protein in StarLink corn in corn-based food products, the likelihood of allergic sensitization to this specific novel protein is low.

Despite that and due to the concerns about the potential allergenicity of this transgenic variety, it has been withdrawn from the marketplace, although traces may remain for one or more growing seasons. This episode emphasizes the importance of assessing the potential allergenicity of transgenic varieties as part of the overall safety evaluation process.

Agricultural biotechnology can also be used to decrease the inherent allergenicity of foods. The proteins in specific foods that are responsible for allergic reactions could be removed or altered through agricultural biotechnology. While no commercial examples exist yet of the application of this possibility, it is an athletic area of research with peanuts.

Sheet BREAK

Non-IgE Cell-Mediated Reactions
As noted earlier, cell-mediated allergic reactions, also known as delayed hypersensitivity reactions, own an onset time of 6–24 hours after ingestion of the offending food.

The reactions develop slowly, reaching a peak at approximately 48 hours and then slowly subsiding over 72–96 hours. Cell-mediated food allergies involve the interaction between specific antigens or allergens from the food and sensitized, tissue-bound T cells that release inflammatory mediators when sensitized (Sampson, ). The role of cell-mediated reactions in food allergies remains somewhat uncertain. Compelling and mounting evidence has accumulated, however, indicating that celiac disease occurs through a T cell-mediated mechanism (Ferguson, ; Strober, ).

Celiac Disease.

Also known as celiac sprue or gluten-sensitive enteropathy, celiac disease is a malabsorption syndrome occurring in sensitive individuals upon the consumption of wheat, rye, barley, triticale, spelt, and kamut (Ferguson, ; Lemke and Taylor, ). The role of oats in celiac disease has recently been questioned. Apparently, oats and oat products that are totally free of wheat, rye, and barley, are safe for celiac sufferers to consume (Janatuinen et al., ). After consumption of the offending grains or products made from these grains, the absorptive epithelial cells in the little intestine are damaged by an inflammatory process (Ferguson, ).

As a result, absorption of nutrients through the epithelium is compromised. The loss of absorptive function along with the ongoing inflammatory process results in a severe malabsorption syndrome characterized by diarrhea, bloating, weight loss, anemia, bone pain, chronic fatigue, weakness, muscle cramps, and, in children, failure to acquire weight and growth retardation (Lemke and Taylor, ; Skerritt et al., ). A part of wheat, the gliadin part, and related part in barley and rye are associated with initiation of celiac disease in susceptible individuals (Skerritt et al., ).

Celiac disease is an inherited trait, but the inheritance is complicated and poorly understood.

Celiac disease occurs in about 1 of every individuals in the U.S. (Kasarda, ). In some other parts of the world, celiac disease occurs more frequently. The highest prevalence occurs among individuals in certain regions of Europe (Greco et al., ; Kasarda, ). Celiac disease seems to happen more frequently among Europeans than among Americans of European descent for unexplained reasons. Celiac disease rarely occurs among individuals of Chinese or African descent (Ferguson, ).

The treatment of celiac disease involves the avoidance of wheat, rye, barley, triticale, spelt, kamut, and oats and products of these grains (Hartsook, ).

The threshold dose of gliadin and related protein fractions needed to provoke celiac disease in sensitive individuals is not precisely known, but symptoms can be elicited by ingestion of little amounts of these grains (Lemke and Taylor, ). If a gluten-free diet is followed, the symptoms of celiac disease will resolve and the absorptive function of the little intestine will be restored. Most celiac sufferers adhere to extremely strict gluten-free diets. In the absence of information on the safety of products made from the offending grains, affected individuals often select to avoid products that contain remarkably little amounts of protein from these sources including rye alcohol, wheat starch, malt extract, and vinegar.

The wisdom of such severely restricted avoidance diets remains to be established.

Food Intolerances
In contrast to true food allergies, food intolerances happen through non-immunological mechanisms. However, love true food allergies, food intolerances affect some individuals in the population but not every. Individuals suffering from food intolerances can generally tolerate little amounts of the offending food or food ingredient in their diet without ill effects.

Food intolerances can be divided into three categories: anaphylactoid reactions, metabolic food disorders, and idiosyncratic illnesses.

Anaphylactoid Reactions. In IgE-mediated food allergies, the release of histamine and other mediators from the mast cells and basophils is mediated by the interaction of IgE with proteinaceous allergens, as described earlier. In contrast, anaphylactoid reactions are caused by substances that bring about the release of the same mediators from mast cells without the involvement of IgE (Lemke and Taylor, ). Some substance in the implicated food is presumed to destabilize the mast cell membranes allowing for the spontaneous release of histamine and the other mediators.

However, no such histamine-releasing substance has ever been isolated or identified in foods, although this mechanism is well established with certain drugs. Strawberry sensitivity is generally cited as the best example of an anaphylactoid reaction. Although strawberries are known to cause adverse reactions (frequently urticaria) in susceptible individuals, there is little evidence for the existence of an IgE-mediated mechanism. Strawberries contain little protein, and no evidence has been found for the existence of a strawberry allergen. Furthermore, there is no evidence for the existence of strawberry-specific IgE in the sera of strawberry-sensitive individuals.

Spontaneous histamine release is thus a plausible mechanism. However, if a substance exists in strawberries that destabilizes mast cell membranes, that substance has yet to be identified. The possibility that strawberry sensitivity is a form of oral allergy syndrome has not yet been excluded, and is an equally plausible mechanism.

Sheet BREAK

Metabolic Food Disorders. Metabolic food disorders result either from inherited defects in the ability to metabolize some component of food or from a genetically sure, enhanced sensitivity to some foodborne chemical that occurs through an altered metabolic pattern (Lemke and Taylor, ).

Lactose intolerance is an example of an illness that occurs when a genetic deficiency affects the host’s ability to metabolize a food component (Kocian, ). In lactose intolerance, an inherited deficiency occurs in the quantity of the enzyme, β-galactosidase, leading to an impaired ability to digest lactose. Favism is an example of a genetic deficiency that enhances the sensitivity to a foodborne chemical. In favism, a genetic deficiency in glucosephosphate dehydrogenase in the erythrocyte results in an enhanced sensitivity to several hemolytic substances that happen naturally in fava beans (Mager et al., ).

These two metabolic food disorders are the most common and best understood illnesses in this category of food intolerances.

Lactose Intolerance. Lactose is a dissaccharide and the principal sugar in milk. Normally, lactose is hydrolyzed into its constituent monosaccharides, galactose and glucose, in the little intestinal mucosa. These monosaccharides can then be absorbed and used as metabolic sources of energy. In lactose intolerance, the activity levels of β-galactosidase, the key hydrolytic enzyme that exists in the mucosal membranes of the little intestine, are diminished (Houts, ; Suarez and Savaiano, ).

Since lactose cannot be absorbed in the little intestine unless it is hydrolyzed to glucose and galactose, the undigested lactose passes into the colon where it encounters large populations of bacteria. The colonic bacteria metabolize the lactose to CO2, H2, and H2O (Lemke and Taylor, ). Abdominal cramping, flatulence, and frothy diarrhea are the predominant symptoms of lactose intolerance (Bayless et al., ) and are the direct result of the action of the colonic bacteria on lactose. The symptoms vary in intensity in concert with the individual level of activity of β-galactosidase in the little intestine and the quantity of lactose ingested.

Lactose intolerance is a fairly common metabolic food disorder.

Lactose intolerance is especially prevalent among some ethnic groups in the world including Greeks, Arabs, Jews, black Americans, Hispanics, Japanese, and other Asians (Houts, ; Suarez and Savaiano, ). Only about % of Caucasians are affected (Suarez and Savaiano, ). Lactose intolerance can own its onset at any age, occurring as early as the age of three (Simoons, ). However, lactose intolerance tends to worsen with advancing age and is often more common and more severe among the elderly (Houts, ; Simoons, ).

The level of intestinal b-galactosidase is generally sufficient at birth to permit digestion of lactose in mother’s milk, but susceptible individuals suffer as a result of decreased activity of this enzyme as life progresses. Lactose intolerance may also happen on a more transitory basis on occasion, secondary to another intestinal illness or infection such as a bout of viral gastroenteritis (Metcalfe, b). Secondary lactose intolerance tends to subside rather quickly after the original illness is resolved.

Individuals with lactose intolerance are capable to control their symptoms through the avoidance of dairy products containing lactose (Lemke and Taylor, ).

However, numerous lactose-intolerant individuals can tolerate some lactose in their diets. The degree of tolerance for lactose is individualistic and variable among such individuals. Yogurt, sour cream, and acidophilus milk that contain athletic cultures of bacteria with b-galactosidase activity, are better tolerated by lactose-intolerant individuals than other dairy products (Kolars et al., ). Lactose-hydrolyzed milk is also available in the marketplace (Paige et al., ).

And, lactose-intolerant individuals can add b-galactosidase to milk just before consumption, and this seems to be an effective practice (Barillas and Solomons, ). Certainly, the level of tolerance for dairy products is much higher with lactose intolerance than it is with IgE-mediated cows’ milk allergy (Taylor, ).

Favism. Individuals with an inherited deficiency of the enzyme, glucose phosphate dehydrogenase (G6PDH), in their erythrocytes are susceptible to favism. Symptoms happen after consumption of fava beans or the inhalation of pollen from the Vicia faba plant (Mager et al., ).

Fava beans contain vicine and convicine, naturally occurring oxidants that are capable to damage the erythrocyte membranes of G6PDH-deficient individuals causing hemolysis and the symptoms of hemolytic anemia (Marquardt, ). G6PDH is a critical enzyme in erythrocytes because it helps to maintain adequate levels of the reduced form of glutathione (GSH) and nicotinamide adenine dinucleotide phosphate (NADPH). GSH and NADPH assist to avert oxidative damage to erythrocytes. In individuals who are G6PDH-deficient, this protective mechanism is nonfunctional and the oxidants in fava beans can exert their hemolytic effects.

In rare cases with repeated exposure, more severe symptoms can happen including hemoglobinuria, jaundice, and renal failure. The onset time after ingestion of the fava beans ranges from 5 to 24 hours. The illness is self-limited, however, with symptoms resolving promptly and spontaneously upon avoidance of further exposure.

G6PDH deficiency is extremely common and affects approximately million individuals on a worldwide basis (Mager et al., ). The prevalence is highest among Oriental Jewish groups in Israel, Sardinians, Cypriot Greeks, African Americans, and certain African populations. This inherited trait is virtually absent among Caucasians, North American Indians, and Eskimos.

Despite the high prevalence of G6PDH deficiency, favism is an unusual occurrence because fava beans are not frequently eaten except in Mediterranean and Middle Eastern locales.

Idiosyncratic Illnesses
Some individualistic adverse reactions to foods are idiosyncratic in that the mechanism for these illnesses is unknown. Numerous reports, mostly anecdotal, own occurred regarding illnesses in certain individuals attributed to certain specific foods or food ingredients. Conceivably, a large number of diverse mechanisms could be involved in these idiosyncratic reactions.

The symptoms involved in idiosyncratic reactions range from unimportant to severe, life-threatening reactions (Taylor et al., b).

Sheet BREAK

The role of specific foods or food ingredients in the causation of these idiosyncratic reactions remains to be sure in numerous cases. The cause-and-effect relationships can only be established through carefully controlled DBPCFCs (Taylor et al., b). A positive DBPCFC would definitely confirm that the specific food or food ingredient is involved in the specific adverse reaction. The mechanism of the adverse reaction, however, cannot be sure from the positive DBPCFC alone.

A negative DBPCFC indicates either that foods are not involved in causation of the reaction or at least that the specific food or food ingredient used in the challenge was wrongly incriminated. Unfortunately, DBPCFCs are rarely performed to establish convincingly that a specific food or food ingredient is associated with a specific idiosyncratic reaction.

The role of specific foods or food ingredients are firmly established in a few of the numerous alleged foodborne idiosyncratic reactions.

Sulfite-induced asthma is perhaps the best example (Bush and Taylor, ). In the case of sulfite-induced asthma, numerous clinicians own documented the role of sulfites in the provocation of asthma in dozens of patients using DBPCFC protocols (Bush and Taylor, ). Aspartame has been identified as a causative factor in two subjects using DBPCFC (Kulczycki, ). However, other cases of aspartame-induced urticaria own not been identified so this may be a rather rare phenomenon.

For numerous other alleged idiosyncratic reactions to specific foods or food ingredients, the association with the specific food or food ingredient has not been conclusively documented through DBPCFCs.

Examples would include the role of chocolate or aspartame in migraine headache; the roles of BHA, BHT, tartrazine, benzoates, or parabens in chronic urticaria; the role of tartrazine in asthma; the role of monosodium glutamate (MSG) in asthma or MSG Symptom Complex; and the role of sugar in aggressive behavior (Bush and Taylor, ). A thorough critique of the numerous studies that own been conducted on the role of these foods or food ingredients in the causation of these idiosyncratic reactions is beyond the scope of this specific review. However, extremely few of the clinical studies own used double-blind and placebo-controlled trial designs.

Furthermore, numerous of the studies own involved individuals with chronic, episodic symptoms such as chronic urticaria or asthma and the clinical investigators own removed critical medications from the patients before initiating the challenge trials. In such cases, the observed symptoms might be due either to the challenge substance or to the withdrawal of medications that controlled the condition. With such critical clinical design flaws, the role of these specific foods and food ingredients in  these specific idiosyncratic illnesses remains unproven.

Furthermore, psychological disorders may be involved in perceived reactions to specific foods or food ingredients (King, ; Selner and Staudenmayer, ).

In a few cases, the role of specific foods or food ingredients in idiosyncratic reactions has been disproven by careful clinical investigations. However, consumers may persist in their belief that such reactions happen. The outstanding example of such a reaction is the role of artificial food colors in hyperkinetic behavior in children. Several decades ago, Dr. Benjamin Feingold implicated artificial food colorants as causative factors in hyperkinesis on the basis of poorly controlled trials and anecdotal experiences (Feingold, ).

The resulting publicity on the Feingold hypothesis was considerable, and, consequently, numerous consumers became convinced of a relationship between ingestion of artificial food colorants and provocation of hyperkinetic behavior in children. Subsequently, several double-blind, placebo-controlled challenge trials own been conducted with artificial food colorants and own demonstrated convincingly that few, if any, hyperkinetic children are adversely affected by the ingestion of these food colorants (Harley et al., a). Despite this evidence, numerous consumers persist in their belief regarding the role of artificial food colorants in hyperkinetic behavior.

A similar situation exists with honor to monosodium glutamate where the involvement of MSG intake in the so called Chinese Restaurant Syndrome, now more appropriately called MSG Symptom Complicated, has been alleged so often that it is now accepted as fact by numerous consumers.

However, the role of MSG in MSG Symptom Complicated has not been corroborated in carefully controlled clinical challenge studies (Kenny, ; Tarasoff and Kelly, ). More recently, MSG intake has been linked to asthma (Allen et al., ). However, the role of MSG in provocation of asthma seems questionable at best when patients are evaluated using a DBPCFC protocol (Bush and Taylor, ). The alleged role of tartrazine, also known as FD&C Yellow #5, in asthma and chronic urticaria is also extremely questionable in the light of DBPCFCs (Bush and Taylor, ; Stevenson et al., ).

Yet, undeclared tartrazine remains the basis for a large number of FDA recalls.

Sulfite-Induced Asthma. Sulfiting agents allowed for use in foods include sulfur dioxide, potassium metabisulfite, sodium metabisulfite, potassium bisulfite, sodium bisulfite, and sodium sulfite. Sulfiting agents own been used as food ingredients for numerous years, because they own numerous significant technological benefits (Taylor et al., b). Sulfites also happen naturally in some foods, especially fermented foods (Taylor et al., b).

However, residual levels of sulfites in foods vary from a few ppm arising mostly from natural sources, to less than 10 ppm to >1, ppm as a result of additive usage.

Sheet BREAK

Although sulfites own been used for centuries, they own been implicated as triggers of asthma in some sensitive individuals only in recent years (Bush and Taylor, ; Stevenson and Simon, ). The reactions generally happen within a few minutes after the ingestion of a provoking dose of sulfite. The reactions can be fairly severe on occasion and deaths own been attributed to sulfite-induced asthma (Bush and Taylor, ).

The role of sulfites in the causation of asthma in susceptible individuals has been well documented by DBPCFC (Bush and Taylor, ; Stevenson and Simon, ). Other symptoms own also been alleged to happen as a result of sulfite sensitivity but these reports own been largely anecdotal and unverified by DBPCFC (Bush and Taylor, ).

Sulfite-induced asthma affects only a little percentage of every asthmatic individuals (Bush et al., ). The prevalence among severe asthmatics who are dependent upon steroid-based drugs for control of their symptoms appears to be in the range of 4–7%, while mild asthmatics do not seem to be extremely susceptible to sulfite ingestion (Bush et al., ).

Thus, the overall prevalence of sulfite-induced asthma is estimated at –% of the entire asthmatic population (Bush et al., ).

Sulfite-induced asthmatics display thresholds for sulfites (Bush and Taylor, ; Taylor et al., ). While the ingestion of high doses of sulfite in highly sulfited foods and beverages can be fairly hazardous for susceptible individuals, the ingestion of sulfited foods with lower levels of residual sulfite (< ppm as entire SO2) seems to present little risk (Taylor et al., ).

Thus, sulfite-sensitive asthmatics must be alert to the presence of sulfites in foods at levels that are required to be declared on the ingredient statement, but are at no risk from ingestion of sulfites from foods that own levels of residual sulfite under the detection limit of current assay procedures (<10 ppm as entire SO2).

The mechanism of sulfite-induced asthma is not known. Several diverse mechanisms own been proposed including IgE-mediated reactions, hypersensitivity to inhaled SO2 from ingestion of acidic foods and beverages, and sulfite oxidase deficiency (Bush and Taylor, ). However, none of these mechanisms has been proven, so sulfite-induced asthma remains an idiosyncratic illness.

Implications for Food Manufacturing

Individuals with food allergy own an overreactive immune systemtowards aparticularfood.

Such a response happens due toan antibody calledIgE (Immunoglobulin E). Individuals suffering from food allergy often own a family history ofallergies.The most common food allergens are the proteins in cow’s milk, eggs, peanuts, wheat, soy, fish, shellfish and tree nuts.

The symptoms on food allergy may not depend on the quantity of allergenic food consumed and may even happen with consumption of tiny amounts. It is also significant to note that numerous allergens may cause symptoms even after they own been cooked, and even after undergoing the digestive process.

On the other hand, some otherallergens, typically certain fruits and vegetables, may only cause allergies when consumed raw.

In some food groups, such as seafood andtree nuts, a phenomenon called cross-reactivity may be seen. This implies that if an individual has an allergy to onemember of a food family, they may also beallergic to other members of the same food group. Interestingly, cross-reactivitymay not be as commonly seen infoods from animal groups. For example, it has been found that individuals who may own allergiesto cow’s milk may still be capable toeat beef. Similarly, individuals with egg allergies may still be abletoeat chicken. It has also been found thatamong shellfish, crustaceans (shrimp, crab and lobster) are most likely to cause an allergic reaction.

Other mollusks such as clams, oysters and scallops are somewhat lesscommonly associated with allergies.

Symptoms of Food Allergies:
Symptoms of allergic reactions are commonly dermatological in nature and may causeskin itching, hives and swelling. Vomiting and diarrhea are common gastrointestinal symptoms. Symptoms of the respiratory system generally happen onlyin conjunction withskin and gastrointestinal symptoms.

Severe Allergic Reactions:
Anaphylaxis is a serious allergic reaction that happens extremely quickly and needs immediate and urgent attention!The symptoms often includedifficulty in breathing, loss of consciousness and dizziness. If you noticeany of these symptoms,especially after eating, call rightaway.

It is imperative to seek medical care immediately (call ). Don’t wait to see if your symptoms go away or get better on their own. Without immediate treatment and effective and expert medical care, anaphylaxis can be lethal. It is essential to follow up with your allergist in such cases.

Diagnosis:
An allergist is the best qualified professional to diagnose food allergy. Your allergist will take a thorough medical history, followed by a physical examination. You may be asked about contents of the foods, the frequency, seasonality, severity and nature of your symptoms and the quantity of time between eating a food and any reaction.

Allergy skin tests may determine which foods, if any, trigger your allergic symptoms.

In skin testing, a little quantity of extract made from the food is placed on the back or arm. If a raised bump or little hive develops within 20 minutes, it indicates a possible allergy. If it does not develop, the test is negative. It is unusual for someone with a negative skin test to own an IgE-mediated food allergy.

In certain cases, such as in patients with severe eczema, an allergy skin test cannot be done. Your doctor may recommend a blood test. Untrue positive results may happen with both skin and blood testing. Food challenges are often required to confirm the diagnosis. Food challenges are done by consuming the food in a medical setting to determine if that food causes a reaction.

Another question that is commonly asked is whether children outgrow their food allergies.

It has been reported that most children may outgrow  certain allergies such as those to soy, egg, cow’s milk, and wheat allergy, even if they own a history of a severe reaction. About 20% of children with peanut allergy will outgrow it. About 9% of children with tree nut allergy will outgrow it. Your allergist can assist you study when your kid might outgrow a food allergy.

Treatment:

The best way to treat food allergy is to avoid the foods that trigger your allergy. Always check the ingredients when eating, especially when out of home. Carefully read labels that indicate food information.

Carefully read food labels.

Always carry and know how to use injectable epinephrine and antihistamines to treat emergency reactions. Teach family members and other people shut to you how to use epinephrine! It is also significant to wear an ID bracelet that describes your allergy.

Food allergies can be confusing and isolating. For support, you may contact the Food Allergy & Anaphylaxis Network (FAAN) at ()

(Information only; not intended to replace medical advice; adapted from AAAAI)

Colonization with the Staphylococcus aureus bacterium was significantly and independently associated with food allergy in young children with eczema enrolled in a pivotal peanut allergy prevention study.

is a marker for severe eczema, and early eczema is a widely recognized risk factor for developing food allergies in young children.

But the findings from the Learning Early About Peanut Allergy (LEAP) study cohort show that even after controlling for eczema severity, skin S.

aureus positivity was associated with an increased risk for developing allergies to peanuts, eggs, and cow’s milk.

S. aureus colonization was also associated with persistent egg allergy until at least age 5 or 6 years in the LEAP cohort analysis in the Journal of Allergy and Clinical Immunology.

The lead researcher, Olympia Tsilochristou, MD, of Kings College London, said in a press statement that the findings could assist explain why young children with eczema own a extremely high risk for developing food allergies. While the exact mechanisms linking the two are not known, «our results propose that the bacteria Staphylococcus aureus could be an significant factor contributing to this outcome,» she said.

The findings also propose that S.

aureus colonization may inhibit peanut tolerance among at-risk infants when peanuts are introduced extremely early in life.

Among the nine participants in the peanut-consumption arm of the study (i.e., no peanut allergy at baseline) who had confirmed peanut allergy at 60 and 72 months, every but one were colonized with S. aureus at one or more LEAP study visits.

«The fact that S. aureus was associated with greater risk of peanut allergy among peanut consumers but not peanut avoiders further suggests that peanut consumption was less effective in the prevention of peanut allergy among participants with S.

aureus compared with those with no S. aureus,» the researchers wrote.

The LEAP study enrolled infants ages months with severe eczema, egg allergy, or both. The babies were randomized to therapeutic peanut consumption or peanut avoidance, and every had eczema clinical evaluation and culture of skin and nasal swabs at baseline.

The follow-up LEAP-On study assessed the children at age 72 months, after 12 months of peanut avoidance in both groups.

Skin and nasal swabs were obtained at baseline and at age 12, 30, and 60 months. A entire of % of the participants had some form of S. aureus colonization (% skin and % nasal) on at least one LEAP study visit, with most having just one positive test result.

The greatest rates of colonization were recorded at months of age.

S. aureus colonization was significantly associated with eczema severity, along with hen’s egg white and peanut specific immunoglobulin (sIg)E production at any LEAP visit. But even after controlling for eczema severity, hen’s egg white and peanut sIgE levels at each LEAP and LEAP-On visit were significantly associated with skin S. aureus positivity, the team noted.

«This relationship was even stronger when we looked into high-level hen’s egg white and peanut sIgE production,» the researchers wrote.

«Similar findings were noted for cow’s milk, where high-level sIgE production to milk at 30, 60, and 72 months of age was related to any skin S. aureus colonization. Together, these data propose that S. aureus is associated with hen’s egg, peanut, and cow’s milk allergy.»

In the LEAP study, extremely early peanut consumption was found to reduce the risk of peanut allergy at 60 months in infants at high risk for developing the allergy, but infants in the consumption arm of the study with S.

aureus colonization were approximately seven and four times more likely to own confirmed peanut allergy at 60 and 72 months, the team said.

Study strengths, Tsilochristou and co-authors noted, included the rigorous design; a limitation was the reliance on bacteriological culture to identify S. aureus colonization rather than using DNA-based testing.

«S. aureus has been implicated in the development and severity of atopic diseases, namely eczema, allergic rhinitis, and asthma; our findings extend these observations to the development of food allergy independent of eczema severity,» the investigators concluded.

«The role of S.

aureus as a potential environmental factor should be considered in future interventions aimed at inducing and maintaining tolerance to food allergens in eczematous infants. Further prospective longitudinal studies measuring S. aureus with more advanced techniques and interventional studies eradicating S. aureus in early infancy will assist elucidate its role in the development of eczema or food allergy,» the team wrote.


RELATED VIDEO: