FOOD ALLERGIES
WHAT IS A FOOD ALLERGY?
An immune reaction that occurs after eating a certain food
Also known as a food hypersensitivity Autoimmune disease
Elicits an abnormal immune response to a harmless food substance Antibodies are released to fight the allergen
Allergen is usually a protein
CLASSIFICATION OF ALLERGIES
Allergic reactions are classified into non-IgE-mediated, IgE-mediated or mixed response Non-IgE
Slower in onset, primarily gastrointestinal reactions IgE mediated
Causes histamine and other chemicals to be released which trigger allergy symptoms
Rapid in onset, symptoms include anaphylaxis & urticaria
SYMPTOMS
Allergy symptoms can occur seconds to hours after ingestion of the allergen
Most common symptoms: swelling, sneezing, nausea, GI distress
FOODS MOST COMMONLY ASSOCIATED WITH ALLERGIC REACTIONS
FREQUENTLY ALLERGENIC FOODS
FOOD ALLERGY VS FOOD INTOLERANCE
Reactions to food consist of a variety of reactions to food or food additive ingestion
Usually not allergenic and caused by food intolerance Symptom-inducing food
properties Metabolic disorders Bacterial food
contamination
VARIABILITY IN PREVALENCE
Determination of the exact prevalence is difficult Considerable variation in
data collection Self-reporting, physician assessment, skin tests, IgE levels
However, self-reports indicate that food allergy incidences are on the rise
Food allergy in infants are most common
INCREASED EXPOSURE
Development of an allergy depends on the structure of the protein, dose of the antigen and the genetic susceptibility of the host
Non-oral exposure may be a primary risk factor Damaged skin may allow increased
exposure before tolerance has been developed through oral ingestion
FOOD ALLERGIES
PEANUT Milk Egg Tree Nuts Fish Shellfish Wheat Soy
PEANUT ALLERGY
Peanut sensitization does not conclude an allergy About 95% of sensitized individuals are not
clinically allergic Attracted the most attention because it is
relatively common, typically permanent and often severe
Significantly increased globally in the past decade 2-3x as common
PEANUT ALLERGYHYGIENE HYPOTHESIS
Antibiotic treatment increased ease of peanut sensitization
Studies from many countries show that early exposure of viral infection may produce a proactive effect
Children born into families with several siblings tend to have a reduced frequency of allergic sensitization
PEANUT ALLERGYPROCESSING Allergenic protein content depends on
processing and varies by brand Higher allergenic protein content:
More mature, larger kernels Drying or curing at higher temperatures Roasting Whipped or emulsified peanut butter
Less allergenic protein content: Small kernels Raw peanuts
Highly processed oils had no detectable protein It is generally advised that peanut-allergic
patients avoid all peanut oils
PEANUT ALLERGYAGE OF INTRODUCTION
Sensitization to peanuts typically occurs at an early age, therefore such patients are more likely to react at first exposure No conclusive evidence has
been found to support the theory that the allergy is developed in utero
Food allergy manifests most commonly in infancy, peaking at 1 year of age and declining by age 3
Recommendations only in place for at-risk infants
MILK ALLERGY
2.5% of children younger than 3
Develops in first year of life
Most children will outgrow it
Baby Formula
Hidden Sources: deli meats, non dairy items, canned tuna fish, restaurant foods and sauces
EGG ALLERGY Affect approximately 1.5% of young children
Likely to be outgrown
Most allergic reactions associated with egg involve the skin
Hidden sources: coffee drinks with foam topping, soft or hard pretzels, cooked pasta, egg substitutes.
Vaccines
TREE NUT ALLERGY
1.8 million Americans Allergic are among the leading causes of fatal
and near-fatal reactions to foods Tree nuts = walnuts, almond, hazelnuts,
coconuts, cashews, pistachios, and Brazil nuts Tend to have a lifelong allergy Hidden sources: Salads and salad dressing,
barbecue sauce, breading for chicken, pancakes, meat-free burgers, pasta, honey, fish dishes, pie crust, mandelonas (peanuts soaked in almond flavoring), mortadella (may contain pistachios)
FISH AND SHELLFISH ALLERGY 2.3% of Americans Salmon, tuna, and halibut Avoid all varieties Lifelong Avoid seafood restaurants Asian restaurants-fish sauce Read ingredient lists Avoid areas where fish is being handled or cooked
Hidden Sources: Salad dressing, Worcestershire sauce, bouillabaisse, imitation fish or shellfish, meatloaf, barbecue sauce (some are made from Worcestershire)
WHEAT ALLERGY
Common in children Often confused with celiac disease IgE-mediated response to wheat protein
May tolerate other grains Symptoms range from mild to severe
Sources: baked goods (wheat flour), pasta, sauces thickened with flour, cereals, crackers
Substitute with amaranth, barley, corn, oat, quinoa, rice, rye, tapioca
SOY ALLERGY
More common food allergies in babies and children
Major ingredient in food products Hard to avoid
Dietitian should be consulted Symptoms typically mild
Hidden sources: baked goods, canned tuna, cereals, crackers, infant formulas, peanut butter, sauces, and soups.
Typically can tolerate soybean oil
CAN SOME INDIVIDUALS BE ALLERGY-PRONE?
Patients reacting to greater numbers of allergenic epitopes experienced more severe allergic reactions & to smaller doses
Children with egg &/or milk allergies more susceptible
Peanut-allergic patients do not usually react to other legumes such as green beans, lima beans, navy beans 95% of peanut-allergic patients can tolerate soy
TREATMENT OPTIONS
CURING FOOD ALLERGIES
There is currently no cure for food allergies The current recommendation is to avoid the
allergen Promising treatments on the way
IMMUNOTHERAPY
Sublingual immunotherapy (SLIT) Oral Immunotherapy (OIT) Contact of an antigen induces tolerance Patient is given increasing amounts of the
allergen
Conclusion: may be effective during therapy (for egg, milk and hazelnut) but there is no evidence for long-term tolerance
ANTI-IGE THERAPY
TNX-901 was given in varying doses 450 mg dose significantly increased threshold of
reactivity to peanuts from 178 mg (about ½ a peanut) to 2.8 g (about 9 peanuts) Enough to protect against accidental ingestions
Results were inconsistent
Would require bimonthly or monthly injections for rest of patients’ life
Conclusion: May be of use in severe cases
ENGINEERED RECOMBINANT PROTEIN
The three major allergenic proteins in peanut Ara h 1, 2 & 3 were isolated
Necessary for binding with IgE The recombinant proteins were significantly
more effective at blocking symptoms The modified Ara h 1, 2 & 3 proteins have
been manufactured and are undergoing testing before application for FDA approval
CHINESE HERBAL MEDICINE
A 9-Herb preparation termed Food Allergy Herbal Formula (FAHF)-2 blocks anaphylactic symptoms Provided full protection against symptoms in a
clinical study performed on mice The FDA has recently approved a botanical
Investigational New Drug application A phase-I clinical trial will soon be underway
SUMMARY COMMENTS
Food allergy is an autoimmune response often mistaken for food intolerance
Peanut allergy appears to be increasing Genetic, environmental and immunological
influences Recent studies have led to improved
diagnoses, management and patient education
Numerous approaches to treatment are underway