Glossary

Diaminoxidase (DAO) is the enzyme that breaks down histamine in the gut. Reduced DAO activity causes histamine to accumulate in the body, triggering symptoms such as headaches, skin reactions, or digestive issues.

Estrogen is a group of female sex hormones that regulate the menstrual cycle, bone health, and cognitive function. Estrogen also influences DAO activity and thus histamine breakdown, which can explain cycle-dependent symptoms.

Histamine is an endogenous chemical messenger that regulates immune responses, digestion, and the sleep-wake cycle. In women, estrogen influences histamine breakdown, which is why symptoms can intensify in a cycle-dependent manner.