Diamine oxidase deficiency implications for health, current management, and future directions in the treatment of histamine intolerance: A review.

Diamine oxidase (DAO) is a key enzyme responsible for the metabolism of histamine, preventing its excessive accumulation and thereby maintaining physiological homeostasis. When DAO activity is insufficient, histamine intolerance (HIT) arises, manifesting as migraines, gastrointestinal disturbances, and allergy-like reactions, among other disorders. This review provides a comprehensive examination of DAO's biological role and its involvement in pathologies associated with impaired histamine degradation. Moreover, genetic and dietary factors influencing DAO activity are explored, emphasising their significance in histamine metabolism. In addition, it analyses clinical trials assessing the efficacy of DAO supplementation, shedding light on its therapeutic potential. Recent advancements in supplementation strategies are also highlighted, particularly those aimed at mitigating HIT symptoms. Furthermore, this review evaluates DAO-rich supplements in detail, focusing on the intrinsic differences arising from their diverse sources. Lastly, current challenges are discussed, including the lack of standardised diagnostic methods, limitations in supplementation efficacy, and gaps in the regulatory framework. By synthesising current evidence, this review aims to offer insights that guide future research and foster the development of innovative diagnostic and therapeutic strategies for the effective management of histamine intolerance caused by DAO deficiency.