Food-allergic asthma in general practice.

A survey was undertaken to assess the importance of food allergy in asthma. Seventy-two asthmatics aged 15-60 years were identified in a general practice and compared with 72 controls matched for age and sex. A diagnostic procedure involving dietary elimination and challenge was carried out on those who thought food exacerbated their symptoms, together with those with concurrent eczema, positive skin tests to food or positive food IgE-RAST. The asthmatics more frequently had positive skin tests of IgE-RAST to food than the controls, but these tests proved to be rather non-specific in identifying provoking foods. One patient was found to be allergic to wheat and his clinical condition improved when wheat was removed from his diet. Two patients seemed to respond to other foodstuffs, but the effects were small, the foods (honey and peppermint) unimportant, and the patients' symptoms appeared to be largely due to other factors. Most cases of alleged food-induced asthma could not be confirmed by challenge testing. This survey suggests that some degree of provocation by food (excluding drink) affects at least 4 per cent of adult asthmatics, although in some of these patients it plays an unimportant part in the disease.