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