Abstract
Purpose: This is a report of the outcome of dietary management (histamine restriction) of 44 subjects referred to a food allergy clinic over a 12-month period for management of 'idiopathic' urticaria, angioedema and pruritus (U/A/P), because their symptoms had resisted previous treatment and because a preliminary study had shown potential response to such a diet in comparison with placebo. Additionally, the effect of this type of dietary management was reported on numerous other symptoms. Design: Statistical evaluation of outcome based on clinical signs and symptoms. Materials and Methods: Because the U/A/P symptoms of the subjects evaluated in the study were characteristic of a histamine mediator response, a histamine-restricted diet was implemented for a 4-week trial. By means of chart audit, symptoms which had been rated by subjects according to severity were compared at the beginning and the end of the trial period, as was the change in intake of antihistamine medication. Results: The degree of improvement in symptoms varied, depending on the symptom reported and the gender and age of the subject. For U/A/P symptoms, 61.4% reported significant improvement, 18.2% reported 'some improvement', while 20.4% showed no improvement. Women (more prevalent) reported a greater degree of improvement than men. Of the additional symptoms, no-one reported improvement in atopic dermatitis or contact dermatitis (n = 4); 50% of subjects reported improvement in migraine headaches, while 50% reported no improvement (n = 10); 80% of subjects with gastrointestinal tract symptoms reported improvement (n = 9); 100% of subjects reporting 'panic attacks' as one of their additional problems (n = 3) reported complete remission of this symptom. Conclusions: A randomized, double-blind controlled trial with an appropriate sample size would be required to ensure that the observed symptom relief in our subjects with recalcitrant idiopathic U/A/P is not due to bias or chance. Considering that a histamine-restricted diet has been beneficial in this uncontrolled pilot study, a time-limited trial on the diet, which poses no risk of nutritional deficiency, may be warranted for subjects exhibiting the type of resistant symptoms reported.