Adverse food reactions Pauline Powell. Young et al. Lancet 1994;343;1127-1130 7500 households in both High Wycombe and the rest of UK 20,000 individuals.

Adverse food reactions

Pauline Powell

Young et al. Lancet 1994;343;1127-1130

• 7500 households in both High Wycombe and the rest of UK

• 20,000 individuals in each location• 19.9% and 20.4% complained of food intolerance• Prevalence of positive reactions by DBPCFC to 8

test substances indicated 1.5% for the study population (egg, milk, wheat, soya, orange, prawn, peanuts and tree nuts, and chocolate)

Food Hypersensitivity among Finnish university students: association with

atopic disease• Postal questionnaire sent to all 1st yr university students - 14202• 413 students identified, 195 asthma/wheezing and 218 symptom free• 296/413 took part in final examination, 152 vs 144• 172/286 (60%) reported food hypersensitivity (F>M)• 10% kiwi and celery (birch/mugwort)• 9% peanut

Clin Exp Allergy 2003; 33: 600-606

• Clin Exp Allergy 2003;33:600-6

Food reactions

• Food allergy including anaphylaxis

• Food intolerance -related to amount

• Food aversion - simple dislikes through to anorexia nervosa and bulimia

• Prophylaxis - with protection

• Anaphylaxis - without protection

• Porter and Richet 1902

Clinical features of Anaphylaxis

• Laryngeal oedema• Hypotension/collapse• Bronchospasm• Feeling of impending doom• Onset usually within minutes• Almost invariably symptoms begin within 60 mins• Generally the later the onset the less severe the

symptoms• 30% have a biphasic reaction, 1-4 hours later

Food Allergy Reactions reported in blinded challenges

• Anaphylaxis, inc food dependent exercise induced anaphylaxis

• Urticaria and angioedema

• Rhinoconjunctivitis, laryngeal oedema, asthma

• Abdominal pain, nausea, vomiting and diarrhoea

Common food allergens

Adults• Peanut• Tree nuts • Fish• Shellfish• Wheat

Children• Milk (cows, goat etc)• Hen’s egg• Peanut• Tree nuts• Soya• Wheat• Fish

Prevalence of anaphylaxis - unknown but increasing

• Mayo Clinic Emergency Dept - 3.5yrs• 179 patients with respiratory and/or CVS

symptoms with urticaria• 66% female• 49% atopic• 37% previous immediate reaction to the

allergen

• Mayo Clin Proc 1994:69:16-23

Probable cause identified in 142/179

• Food 33%

• Bee sting 14%

• Medications 13%

• Exercise 7%

• Idiopathic 19%

Foods implicated

• Peanut

• Cereals - wheat

• Egg

• Tree nuts

• Milk

• 5yr survey at Children’s Hospital of Philadelphia• 7 cases of fatal anaphylaxis during a 16 month

period• 6/7 unknowingly ingested a food that provoked a

previous allergic reaction

• JAMA 1988;260:1450-1452

Fatalities due to anaphylaxis

Risks factors• Asthma - albeit well controlled• Unaware of ingesting food allergen• All experienced previous allergic reaction to

the incriminating food - usually milder• All had immediate symptoms• Half experienced quiescent period prior to

major respiratory collapse

• NEJM 1992;327:380-384

Incidence of food allergy maximal in first 2yrs of life and decreases with age

• Cow’s milk*-3 years• Egg* - 5 years• Soy (bean)*• Wheat• Peanut, tree nut, fish and shellfish allergy

often persist into adulthood• *usually outgrown

Increased exposure may result in increased prevalence

• Peanut in USA

• Cod fish in Scandinavia

• Rice and buckwheat in Japan

• Sesame in Israel - in tehini and halva

second only to milk Allergy 57:362-5;2002

Food problems in latex sensitive individuals

• Banana• Kiwi• Avocado• Sweet chestnuts• Melon

• Peach• Papaya• Passion Fruit• Fig• Celery

Latex allergy-risk factors

• Atopic status and hand eczema

• Health care personnel

• Patients undergoing multiple operations

• Rubber industry workers

Birch pollen oral food syndrome- usually raw fruit and vegetables

• Hazel nut• Apple• Peach• Cherry• Almond• Plum• Kiwi• Apricot

• Potato peel• Brazil nut • Cashew• Tomato• Celery• Fennel• Carrot

Allergy skin testing in predicting positive challenges

• 555 challenges in 467 children • 339 cows milk, 121 egg, 95 peanut.• 55% challenges positive, 37%negative, 18%

inconclusive• No negative challenges if skin weal

diameter > 8mm milk, 7mm egg, 8mm peanut (100% specificity)

• By utilizing these measurements, the need for formal food challenges can be reduced

• R. Sporik et al. Clin Exp Allergy 2000; 30:1540-1546

Peanut- the most allergenic food

• Family Leguminosae• Ground nut• Arachis oil - previously in nipple creams• Monkey nuts

• Can affect all ages; < 20% can outgrow this allergy, particularly if they have early onset (< 1yr) and mild symptoms.Hourihane, BMJ 1998:316:1271-5

Seafood

Crustaceans• Shrimps• Prawns• Crabs• Lobster• Crayfish

More important

Molluscs• Clams • Scallops• Oysters• Mussels• Snails• Squid• Octopus

Food additives

• Sulphites and Papain are the only ones for which evidence of ‘anaphylaxis’ exists.

Factors that enhance severity of anaphylaxis

• Exercise

• Viral infection

• Asthma

• Stress

Diagnosis• Very careful history • Inciting food is usually obvious• Cooked or uncooked• Concealed ingredients• Contaminants• “Natural flavouring” e.g. casein• Exclude scombroid poisoning

Laboratory evaluation 1

• Identify specific IgE antibody in vivo or in vitro

• A negative skin prick test is a excellent predictor for a negative IgE mediated food reaction in patients with anaphylaxis

Skin prick testing issues• Concomitant antihistamines

• Sub-optimal allergen extracts

• Carry over

• Use of natural food - prick to prick testing

• Use negative and positive controls

• NEVER do intradermal testing without prior skin prick testing

Specific IgE antibodies• Skin prick testing (>3mm bigger than neg)

• ‘RAST’ testing

• Overall, ‘RAST’ is considered less sensitive and less specific than skin prick testing

• DBPCFC is contraindicated in patients with an unequivocal history of anaphylaxis following the isolated ingestion of a food to which they have significant IgE antibodies

Management of food allergy

• Prevention is the cornerstone but mistakes do happen!

• Education - home and schools, emergency treatment plan

• Self injectable epinephrine (Epipen/Anapen)-for whom?

• Junior 0.15mg vs Senior 0.3mg - use early in anaphylaxis

• Antihistamine - tablet or liquid - Zirtec sugar free

• Hydrocortisone iv/im to prevent late phase reactions

• MedicAlert scheme

• Anaphylaxis campaign

• Food re-introduction for milk and egg only

Interactions with adrenaline

Blockers

• Amitriptyline (tricyclics)

The future• Improved food labelling regulations

• Avoidance inadvertent contamination

• Avoid defensive labelling

• ?Desensitisation/anti IgE

• Nutritional genomics