Introduction: Histamine intolerance (HIT) is a multisystem disorder characterized by the excessive accumulation of histamine in the body, primarily due to reduced activity of the diamine oxidase (DAO) enzyme. This condition leads to a range of clinical manifestations, including headaches, gastrointestinal symptoms, fatigue, joint pain, and skin rashes. These symptoms complicate both diagnosis and clinical management, making it challenging for healthcare providers to offer effective treatment options. Objective: The objective of this study was to evaluate the effectiveness of NaturDAO, a plant-based DAO supplement, in reducing symptoms associated with HIT under real-world conditions. Methods: An initial sample of 231 subjects was recruited for the study, with 165 adults (mean age 42.7 years; 71.43% diagnosed with probable HIT) completing a clinical questionnaire before and after two months of home-based supplementation with DAO. Participants provided information on their symptoms and reactions to histamine-rich foods via a self-administered electronic platform. Results: After two months of supplementation, notable reductions were observed in the prevalence of migraines (-30.4%), gastrointestinal symptoms (-47.1%), fatigue (-72.2%), and cutaneous manifestations (-64.4%). Furthermore, 55.8% of participants reported a decrease in their medication needs, while 53.3% experienced improved tolerance to histamine-rich foods. Conclusion: The findings indicate that vegan DAO supplementation (NaturDAO), when combined with dietary recommendations, can yield clinically relevant improvements in symptoms among adults with suspected HIT. This supports the supplements utility beyond hospital settings. The results underscore the need for further studies involving larger populations to confirm these findings and explore the long-term effects of DAO supplementation on symptom management in HIT patients.
Moran et al. (Fri,) studied this question.