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MANAGEMENT OF FOOD ALLERGY

By:

TOOBA MOMEN

Clinical Allergist & Immunologist

ADVERSE REACTIONS TO FOODS

Food intolerance (most common)

Food allergy (hypersensitivity)

Food aversion (phobia)

FOOD INTOLERANCE

It caused by factors inherent in food ingested:

Enzyme Deficiency

GI disorders

Anatomical defect

Physiological effects of Active Substances

Food Additives & Contaminants

Neurologic disorder

FOOD ALLERGY

An adverse health effect arising from a specific immune that occurs on exposure to a given food

E P I D E M I O L O GY O F F O O D A L L E R GY

Food allergy is on the increase in developed countries

Factors contributing to the epidemic appear to be related to the modern lifestyle but as yet are poorly understood.

The incidence of food allergy-related anaphylaxis, the most severe consequence of food allergy, is rising particularly in the under 4-year age group.

Overall more than 90% of food allergies in children are caused by cow’s milk, hen’s egg, soybean, wheat, peanut, tree nut, fish, and shellfish. → overall 8%In adults sea food( 2.3%), peanut& tree nut(1.2%) → overall 3.5-4 %

FR EQ UENTLY ALL ERGEN IC FO O DS

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

PATHOPHYSIOLOGIC MECHANISMS OF FOOD ALLERGY

In the susceptible host, a failure to develop or a breakdown in oral tolerance, commonly a result of heavy occupational exposure or sensitization to cross-reactive allergens may result allergic responseIgE mediated

Non IgE mediated

Mixed IgE & non IgE mediated

Immediate <1 hour

Delayed >24 hours

Volume required for reaction

Class IgE mediated

Non-IgE mediated

Time to onset of reaction

Immediate<1 hour

Delayed>24 hours

Volume required forreaction

Small (e.g. <10 ml) Large (e.g. >100 ml)

Symptoms/ syndromes

Urticaria, angioedema,vomiting, anaphylaxis,oral allergy syndrome,eczema

Diarrhoea, eczema, failure to thrive, gastrooesophageal Reflux,food proteininduced enteropathy, enterocolitis and proctocolitis, multiple food allergy

Diagnosticprocedures

Above signs or symptoms byhistory or oral food challengeAND positive IgE antibodies(skin prick test or cap-FEIA)

Home based elimination andRechallenge sequence (no riskof anaphylaxis

MANIFESTATIONS OF FOOD ALLERGY

CUTANEOUSIgE mediated:

Urticaria, Angioedema

Contact urticaria

Mixed IgE &non IgE mediated:

Atopic dermatitisNon IgE mediated:

Contact dermatitis

Dermatitis herpetiform

GASTROINTESTINLIgE mediated: Acute gastrointestinal hypersensitivity

pollen-food allergy syndrome

IgE & non IgE mediated: Eosinophilic esophagitis

Allergic eosinophilic gastroenteritis

Non IgE mediated: Allergic proctocolitis

food protein induced entrocolitis

food protein induced enteropathy,

celiac

RESPIRATORYIgE mediated Allergic rhinoconjuctivitis

Allergic bronchospasm

IgE & non IgE mediated: Asthma

Non IgE mediated Pulmonary hemosiderosis

DIAGNOSIS & MANAGEMENT OF FOOD ALLERGY

HISTORY &PHYSICAL EXAMINATION

Food presumed to have provoked the reaction

Quantity of the suspected food ingested

Length of time between ingestion &development of symptoms

Whether similar symptoms developed on other occasions when the food was eaten

Whether other factors (exercise, alcohol, drugs) are necessary

How long since the last reaction to food occurred

Personal hx of atopy

Family hx of food allergy & atopy

Diet diaries

DIAGNOSTIC TEST

SKIN PRICK TEST

Skin prick or puncture tests to foods are very useful when properly performed and interpreted.

Negative prick/puncture skin tests have a high negative

predictive accuracy for many foods (>95% for the common foods). Positive prick/puncture skin tests have a high

positivepredictive accuracy for egg, milk and peanut in youngchildren, and the size of the skin test is relativelypredictive. A negative test with a suspicious history requires afood challenge before the food is returned to the diet

INVITRO TEST FOR SPECIFIC IGE

Food specific IgE exceeding the diagnostic values indicate that patients are more than 95% likely to experience allergic reaction after ingestion of specific food

PREFERENCE FOR IN VITRO TESTS VS SKIN TESTSPatients with extensive dermographia

Patients with extensive atopic dermatitis or generalized urticaria

Patients who cannot discontinue antihistamines

Areas where there are no allergists to perform skin testing

ORAL FOOD CHALLENGE PROCEDURES

Oral food challenges (particularly double-blind placebo-controlled food challenge) represent the accepted gold standard investigation for objective diagnosis of both immediate and delayed-onset food allergy.

Oral food challenges are clinically indicated to demonstrate allergy or tolerance to achieve safe dietary expansion or appropriate allergen avoidance

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CHALLENGEDouble-blind Placebo-controlled Food Challenge (DBPCFC)

• Freeze-dried food is disguised in gelatin capsules• Identical gelatin capsules contain a placebo (glucose

powder)• Neither the patient nor the supervisor knows the

identity of the contents of the capsules• Positive test is when the food triggers symptoms

when the placebo does not

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CHALLENGE CONTINUED

Single Blind Food Challenge• Supervisor knows the identity of the food• Food is disguised in strong-flavoured food e.g. apple

sauce; lentil soup

Open Food Challenge• Sequential incremental doe challenge (SIDC)• Determines sensitivity and dose tolerated for each eliminated food

in its purest form

INDICATION FOR OFCIndication RationaleDemonstrate tolerance

1. Allergy suspected to have been outgrown, e.g. the child who was previously eggallergic but now returns ever-decreasing allergy test results.2. When the food has been tolerated in some presentations but not others e.g. baked egg in cakes tolerated but scrambled egg causes a reaction.3. When allergy tests suggest tolerance, but food never eaten and patient and/orparent too cautious to introduce at home.4. Cross-reactivity suspected, e.g. the child with a low positive IgE result to wheat but high positive grass pollen sensitization.5. When the diet is restricted due to a suspicion that one or more foods is resulting in delayed allergic symptoms, e.g. eczema, gastroesophageal reflux.6. To establish a tolerance threshold to allergen proteins (currently restricted to theresearch setting).7. When multiple dietary restrictions are maintained but symptoms are subjective.

Demonstrate allergy 1. Suspected food allergic reaction but cause uncertain despite SPT and Sp-IgE testing,

2. Suspected food allergic reaction but equivocal or inconsistent symptoms following consumption of a particular food

Monitor therapy for food allergy

To monitor response to immunomodulatory treatment in the research setting.

INDICATIVE OF IGE MEDIATED

Skin prick test, and or food specific IgE

Negative

Reintroduction of food into diet; If convincing history of anaphylaxis consider OFC

Positive

Convincing h/o allergic reaction

NOConsider OFC and reintroduction of

food

YESStrict dietary food

avoidance; nutritional support

Periodic reassessment; if specific IgE is detectable,

reintroduction should be done as OFC

I N D I C AT I V E O F C E L L M E D I AT E D O R M I X E D M E C H A N I S M

Biopsy, Serologic test for Celiac, Peripheral Eosinophil, ,Stool for

occult Blood, Hb, Albumin, Total protein

Consider skin prick test or Specific IgE

Trial of Elimination Diet, foods selected based on experience

&result of screening test; if food specific IgE is detectable OFC may

be done for reintroduction

Resolution

NOReview diet &

reconsider food. Correct diagnosis?

YesStrict diet

FOOD ALLERGEN AVOIDANCE STRATEGIES

Should be prescribed based on confirmed diagnosis

Some times strict avoidance in not necessary

-extensively heated product for egg or milk allergy

- maternal ingestion of allergen while breast feeding

- raw fruit & vegetables causing oral symptoms

Labeling of manufactured product

Cross contact

LABELING

MANNER OF EXPOSURE

Skin contact

Inhalation

Ingestion

EXAMPLES OF FOOD ALLERGENS IN UNEXPECTED AND NONFOOD ITEMS

Cosmetics almond or milk in shampoos or ointments

Pet food milk, egg, fish, soy

Medications lactose in DPI or tablet , soy lecithin

Vaccines egg(influenza, yellow fever), milk(DPT)

Nutrition supplements glucosamine chondrotin supplements(shark cartilage or shrimp shell)

Saliva(kissing) residual protein from meals

Transfusion containing allergen from donor ingestion

N A T U R A L H I S T O R Y O F F O O D A L L E R G Y

Most young children outgrow their food sensitivity within a few years except in most cases of peanut, tree, and seafood

Milk Allergy:

most of them become tolerant till 3y/o, 50% by 1y/o, 70% by 2 y/o, 85% by 3 y/o

Egg Allergy:

66% become tolerant by 5 y/o

Peanut Allergy: 20% become tolerant with age

Tree nut Allergy : 9% become tolerant with age

EMERGENCIY MANAGMENT

Prompt recognition of reaction

Treatment with epinephrine and antihistamines

Emergency plans and special considerations for schools

FOOD ALLERGY PREVENTION

C H A N G E S I N N O T I O N S A B O U T A L L E R G Y P R E V E N T I O N T H R O U G H D I E T

Prior notion/recommendation for those at risk for atopy

Recent notion

Avoid peanut during pregnancy No proof of effectiveness

Avoid food allergens during lactation Possible reduction in eczema, no evidence regarding food allergy

Exclusive breast feeding for 3-4 months

May protect for atopy, but evidence is modest, lack of evidence for food allergy prevention

Alternative hypoallergenic formula May protect for atopy, but evidence is modest, lack of evidence for food allergy prevention

Delay complementary foods until 4-6 months

Lack of evidence to prevent atopic disease

Avoid allergens: milk to 1y/o, egg to 2y/o, and peanut, nut , and fish to 3 y/o

Early introduction of allergenic foods at 4-6 m/o may protect against development of food allergy, but firm evidence is lacking

F U T U R E T H E R A P E U T I C S T R A T E G I E S

Strict avoidance of allergens is not curative and leaves patients

at risk for accidental exposure. As such, several new therapeutic

approaches are being tested in clinical trials.

ALLERGEN NON SPECIFIC THERAPIES

Humanized monoclonal anti- IgE

Traditional Chinese Medicine

Probiotics &Prebiotics

ALLERGEN SPECIFIC IMMUNOTHERAPY

Oral immunotherapy

Extensive heated milk & egg proteins

Sublingual Immunotherapy

Epicutaneous Immunotherapy

Modified or recombinant allergen immunotherapy

SUMMARY

Current therapy for food allergy requires education about avoidance in a variety of setting & instruction on when &how to treat inevitable allergic reactions

Current therapeutic strategies are focused on harnessing oral tolerance to modulate allergic response using Ag-specific & non specific approaches.

THANK YOU FOR YOUR ATTENTION