The role of diet in allergic dermatoses.

The association offoods with atopic dermatitis, urticaria and dennatitis herpetiformis has been known for a long time. “Food allergy” has become a fashionable diagnosis although its basis may be insubstantial. Ingested allergens undoubtedly play a role in the symptoms of some atopic patients and gastrointestinal signs suchas lip swelling, vomiting, diarrhoea and pmritus ani may be associated as well. Salicylates and food additives particularly colours could alter children’s behaviour and development. Food intolerant children have been found to be 1.5 cm shorter than normal children. Atopic eczema Food allergy/intolerance may trigger atopic dermatitis (AD) in a small subgmup of patients and is more commonly implicated in children than in adults . The Radio allergosothent tests (RAST) and skin-prick tests have given a further stimulus to dietary factors in this disease. Food appears to be more important than food additives when diet is involved inthe worsening of eczema. Food intolerance exists in 0.3% to 20% of children. Although 20% of parents suspect their children (under 6 years) to have food related illness, only 20% to 30% of these will have this confirmed by appropriate challenge and the tme figure for food intolerance could be around 5% . In 1992, a study confirmed the relation between food allergy and atopic disease in 250 children with AD. Ninety-six percent of all children with severe AD had food sensitivity. The most commonly implicated foods were eggs, cow’s milk, fish, shellfish, corn starch, peanuts and soybeans. Food sensitivity persisted in 67% of children with severe atopic dermatitis upto 7 to 15 years of.age and was always associated with aero-allergen sensitivity Type I food allergy occurs predominantly in those patients with AD who have a predisposition to respiratory atopy. RASTs performed in 183 patients with AD showed that about half of them had type I allergy to atleast one of the five common foods. The RAST correlated roughly to the severity of dermatitis. In each group of patients with mild, moderate and severe AD, positive RAST reactions to common foods occured mainly in patients who had a personal orfamily8history of respiratory atopy and were rare in cases of pure AD Food intolerance has been frequently observed in AD patietns with high IgE levels. In another study, IgE binding components of wheat, rye and oats were recognized by immunoblotting analysis with sen from adults with AD Immediate hypersensitivity to bakery, brewery and wine products (beer, aged red wine, young and sparkling white wine and extracts of fresh wheat bread and dried rye bread) in yeast sensitive patients has also been described. Rice allergy was noted in severe AD in Japan, the clinical severity of which was closely related to the semm IgE values and RAST positivity. Colourings and preservatives have been implicated in some children Food allergies often subside with age. Allergy to cows milk was recognized in ancient Greece and the familial nature of astluna was ttported by Maimonides in 1100 AD. Cow’s milk intolerance affects up to 7.5% of young children, but 80% of these are expected to get over their intolerance by the age of 3 years. Egg and wheat intolerance is transient in children, but allergy to fish/shellfish, peanuts and tme nut is persistant.