A Popular myth - low-histamine diet improves chronic spontaneous urticaria - fact or fiction?

Abstract

Chronic spontaneous urticaria (CsU) is a frequent dermatological disease that might last for months or years with high impact on quality of life. Known causes are autoreactive phenomena, infections or intolerances, rarely IgE-mediated allergies. One-third of CsU patients benefit from a low-pseudoallergen diet. Additionally, it is often discussed, that reducing histamine ingestion alone might improve clinical symptoms and quality of life in CsU patients despite the uncertain role of the histamine-degrading enzyme diamine oxidase (DAO). Aim of this study was to investigate the impact of low-histamine diet on symptoms and quality of life in patients with CsU. Patients suffering from CsU accompanied by gastrointestinal symptoms were included in the study. They underwent low-histamine diet for at least 3 weeks. During the whole study, urticaria activity score (UAS) was recorded daily in a patient's diary. Quality of life was assessed during screening, baseline and post diet visits by completing questionnaires (DLQI and Cu-Q(2)oL). DAO activity was measured before and after elimination diet. A total of 75% of the patients had a benefit from the low-histamine diet. Thirty-four of 56 patients (61%) reached the primary endpoint of the study, an improvement of UAS 4 of ≥3. Overall, a significant reduction from 9.05 to 4.23 points (P = 0.004) was achieved; the average reduction in a strongly affected subgroup was 8.59 points (P < 0.001). DAO activity remained stable. Low-histamine diet is a therapeutically useful, simple and cost-free tool to decrease symptoms and increase quality of life in CsU patients with gastrointestinal involvement. Further research is needed to understand the role of diamine oxidase.