Evaluation of the Safety and Tolerability of Three Single Ascending Doses of Diamine Oxidase (DAO) in Healthy Volunteers: A Randomized Clinical Trial

Background/Objectives: Diamine oxidase (DAO) enzyme metabolizes dietary histamine in the gastrointestinal tract. DAO deficiency can lead to histamine intolerance (HIT), manifesting as migraines, gastrointestinal disturbances, and allergic reactions. DAO supplementation has been shown to enhance histamine breakdown, alleviating these symptoms. This randomized, double-blind, single ascending dose (SAD) Phase I clinical trial aimed to evaluate the safety and tolerability of escalating doses of DAO supplementation in healthy volunteers. Methods: Thirty participants were randomly assigned to receive single doses of 42 mg, 84 mg, or 210 mg of DAO extract (adiDAO® Veg) or placebo under fasting conditions. Vital signs, laboratory parameters, and adverse events (AEs) were monitored. Results: No serious adverse events or clinically significant changes in vital signs, ECGs, or laboratory parameters were observed. Conclusions: This trial confirms the safety and tolerability of high-dose DAO supplementation. Future studies are recommended to explore the effects of chronic high-dose administration and alternative dosage forms to improve convenience.