DAO Enzyme contains a purified form of diamine oxidase (DAO), the primary enzyme responsible for breaking down dietary histamine in the gut before it enters systemic circulation. By supporting histamine degradation at the intestinal barrier, DAO Enzyme helps to alleviate histamine reactions from dietary triggers. This formula is highly concentrated, delivering 30,000 Histamine Degrading Units (HDUs) per capsule for effective histamine balance.

Histamine is a biogenic amine derived from histidine, and functions as a neurotransmitter, immune mediator and local signaling molecule. It interacts with various receptors (H1–H4), leading to effects like vasodilation, inflammation, smooth muscle contraction and sensory nerve stimulation. Histamine is present within most bodily tissues and can be synthesized in large amounts by white blood cells.

Histamine is not only produced in the body but is present in a wide range of foods produced by bacteria that decarboxylate histidine into histamine. Foods prone to high histamine content include aged or fermented products and refrigerated leftovers. Specifically, matured cheeses, cured or processed meats, fish, and fermented beverages like beer and wine commonly contain elevated histamine levels. Histamine overload may occur after consuming foods with a high histamine content that overwhelms endogenous degradation mechanisms. Even lower histamine amounts found in common food servings can provoke symptoms in sensitive individuals with compromised DAO activity or histaminergic food reactions.