adverse food reactions pauline powell. young et al. lancet 1994;343;1127-1130 7500 households in...
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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