Diamine Oxidase Supplementation in Chronic Spontaneous Urticaria: A Randomized, Double-Blind Placebo-Controlled Study.
Level 2 - randomized trial
Double-blind, placebo-controlled randomized crossover trial
PubMed 29698966 · doi:10.1159/000488142
What was done
In a double-blind, placebo-controlled crossover trial, 22 patients with chronic spontaneous urticaria (CSU) incompletely controlled by first-line antihistamine therapy received 30 days of oral diamine oxidase (DAO) supplementation (1 capsule twice daily, 15 minutes before meals) or placebo. The outcome measured was the change in disease severity using the 7-Day Urticaria Activity Score (UAS-7), along with daily antihistamine usage and baseline serum DAO activity.
What was found
Twenty patients completed the study. In patients with low baseline serum DAO levels, DAO supplementation resulted in a 3.8 ± 1.2 point (mean ± SEM) reduction in UAS-7 score compared to placebo (p = 0.041). The extent of UAS-7 improvement was inversely correlated with basal DAO levels (p = 0.019). Patients receiving DAO also showed a slight reduction in daily antihistamine dose compared to placebo (p = 0.049).
Why it matters
This study provides preliminary evidence that histamine intolerance via low endogenous DAO activity may contribute to CSU, and targeted oral DAO supplementation may offer an adjunctive therapy for poorly controlled patients.
Limits
The trial had a very small sample size (20 completers), limiting statistical power and generalizability. The primary improvement was observed only in the subset with low baseline DAO rather than the unselected cohort, and the abstract does not report the crossover washout duration, specific cutoff values for DAO deficiency, or long-term outcomes beyond 30 days.
Cited by
- supports Diamine oxidase (DAO) is an enzyme taken orally to digest or break down dietary histamines.