Food Allergies

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Food Allergies
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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

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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

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Symptoms

• Allergy symptoms can occur seconds to hours after
  ingestion of the allergen
• Most common symptoms
• swelling, sneezing, nausea, GI distress

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Foods most commonly associated with allergic
reactions
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Frequently allergenic foods

• Most common food allergies in young children
• Milk (casein, whey)
• Eggs
• Wheat (gluten)
• Soy
• Peanuts
• Tree nuts
• Shellfish
• Most common food allergies in older children
  adults
• Fish
• Shellfish
• Peanuts
• Tree nuts

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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

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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

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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

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Food Allergies

• PEANUT
• Milk
• Egg
• Tree Nuts
• Fish
• Shellfish
• Wheat
• Soy

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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

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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

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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

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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

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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

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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

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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)

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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)

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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

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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

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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

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treatment options
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Curing Food Allergies

• There is currently no cure for food allergies
• The current recommendation is to avoid the
  allergen
• Promising treatments on the way

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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

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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

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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

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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

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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