Effects of a pseudoallergen-free diet on chronic spontaneous urticaria: a prospective trial.

BACKGROUND Chronic spontaneous urticaria is a skin disorder that is difficult to manage and can last for years. 'Pseudoallergens' are substances that induce hypersensitive/intolerance reactions that are similar to true allergic reactions. They include food additives, vasoactive substances such as histamine, and some natural substances in fruits, vegetables and spices. Eliminating pseudoallergens from the diet can reduce symptom severity and improve patient quality of life. AIM To assess the effects of a pseudoallergen-free diet on disease activity and quality of life in patient's chronic spontaneous urticaria. METHODS Study subjects had moderate or severe chronic spontaneous urticaria that had not responded adequately to treatment in primary care. For 3 weeks, subjects followed a pseudoallergen-free diet. They kept a clinical diary, which recorded their wheal and pruritus severity each day, to yield a clinical rating of chronic spontaneous urticaria severity (the UAS4 score). The subjects also completed the DLQI, a validated quality-of-life instrument. Use of antihistamines and glucocorticoids was minimized, recorded, and analysed. Subjects were classified into nine response categories, according to the changes in symptom severity (UAS4), quality of life (DLQI) and medication usage. RESULTS From the 140 subjects, there were 20 (14%) strong responders and 19 (14%) partial responders. Additionally, there were nine (6%) subjects who made a substantial reduction in their medication without experiencing worse symptoms or quality of life. CONCLUSIONS Altogether the pseudoallergen-free diet is beneficial for one in three patients. The pseudoallergen-free diet is a safe, healthy and cost-free measure to identify patients with chronic spontaneous urticaria that will benefit from avoiding pseudoallergens.