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.