Food allergy

Food allergies, defined as an immune response to food proteins, affect as many as 8% of young children and 2% of adults in westernized countries, and their prevalence appears to be rising like all allergic diseases. In addition to well-recognized urticaria and anaphylaxis triggered by IgE antibody-mediated immune responses,there is an increasing recognition of cell-mediated disorders such as eosinophilic esophagitis and food protein induced enterocolitis. New knowledge is being developed on the pathogenesis of both IgE and non-IgE mediated disease. Currently, management of food allergies consists of educating the patient to avoid ingesting the responsible allergen and initiating therapy if ingestion occurs. However, novel strategies are being studied, including sublingual?oral immunotherapy and others with a hope for future.

Approximately 25% of the United States population believes that they have an allergic reaction to foods.However, the actual incidence confirmed by history and challenges suggests a prevalence rate closer to 2-8% in young infants and less than 2% in adults. The most common food allergies in the United States are milk, egg, peanut, soy, wheat, tree nuts, fish and shellfish. The individual food allergy does vary by culture and population.

Many studies in the past few decades have shown that although 40%-60% of parents believed their child’s symptoms are related to food consumption, only 4%- 8% of children have symptoms reproduced by oral food challenges. The prevalence of food allergy is highest in infants and toddlers (6-8%) and decreases slightly with age, affecting almost 4% of the adults. The most common food allergens in the pediatric population include cow’s milk, eggs, peanuts, tree nuts, soy, wheat, fish, and shellfish, whereas peanuts,tree nuts, fish, and shellfish predominate in adults in the United States (US). The prevalence of sensitization to the specific food allergens varies based on the age and characteristics of the studied population, but studies incorporating diagnostic food challenges currently estimate that the prevalence of cow’s milk allergy in infants is 2.5%, egg hypersensitivity prevalence in young children is 1.6% and peanut allergy is estimated to be between 0.8 and 1.5%

Diagonis

The patient’s history can be a powerful tool, especially if the patient and family are objective historians.But the family’s own perceptions and knowledge often influence history. Food allergy is clearly suspected more often than it is found by accurate diagnostic procedures and is confirmed by challenges in less than 20% of the time. In general, the history can be more helpful in IgE-mediated disorders, because these reactions occur so soon after food ingestion and because multiple target organs are affected. History is harder for food-protein induced enterocolitis, where symptoms occur hours later or days later in

eosinophilic esophagitis.

FOOD ALLERGY THERAPY

The only proven therapy is food elimination. However, many families find it is difficult to read labels as many foods have multiple ways to call an ingredient (for example, casein, whey and lactoalbumin for milk). Therefore, governments enacted labeling laws.For example, in Japan, labeling of food for common

allergies by Ministry of Health, Labour and Welfare (2001) mandate labeling for 5 food (milk, egg, peanut, wheat and buckwheat) with Ministerial Ordinance No.23 of 2001 and recommended labeling for 19 more foods (abalone, squid, salmon roe, shrimp?prawn, orange, crab, kiwifruit, beef, tree nuts,salmon, mackerel, soybeans, chicken, pork, Matsu take mushrooms, peaches, yams, apples and gelatin).

The United States enacted FALPCA in 2005 to help with reading labels to prevent accidental exposure to foods for 8 most common food allergens (milk, egg, peanuts, tree nuts, fish, shellfish, soy, and wheat). Allpatients at risk for anaphylaxis must be trained to identify early symptoms and be prepared to treat appropriately. Auto-injectable epinephrine is essential together with education to help identify avoidable

risks.

FUTURE THERAPIES

One alternative approach to prevent food allergies was to delay the introduction, promote breast feeding

or remove the allergen from the mother’s diet during pregnancy. Overall, these therapeutic options have not been successful. In fact, the recent study by Lack and colleagues suggest that the delayed introduction of peanut in the England can account for the increased food allergy compared to “genetically” matched control group in Israel with 10 fold peanut allergy in England. However, this can not account for the increased rate of sesame seed allergy in Israel, which is also introduced early into the diet. The only dietary measure which has been shown to be important in well conduced longitudinal studies is the introduction formulas and solid foods into infants’ diet before 4-6 months of age diets. Therefore, the American Academy of Pediatrics no longer recommends food avoidance during pregnancy and has no specific recommendation on food reintroduction beside breast feeding and no solids until 4 months of age.

CHINESE HERBAL THERAPIES

Recent work by Li has suggested the unique combination of herbs Zhi Fu Zi (Radix Lateralis Aconiti Carmichaeli Praeparata) and Xi Xin (Herba Asari),could also help with the induction of tolerance.

As a conclusion it can be said,food allergies are a common pediatric condition affecting 4-6% of the US population. Food allergies are continuing to rise similar to other food allergies, but the exact cause for the rise is unknown. Increased understanding for the pathogenesis of both IgE and non-IgE mediated reactions have been done with the use of new techniques and murine models. These advances are creating the opportunities for novel therapies for food allergy. However, at the current time,the only treatment is avoidance.