HISTAMINE INTOLERANCE

Histamine is a biological amine synthesized from the amino acid histidine by L-histidine decarboxylase (HDC) and requires vitamin B6 as a cofactor. Histamine is synthesized and stored predominantly in mast cells - in tissues, but also in basophils and platelets in the blood, in neurons - in the nervous system and in enterochromaffin-like cells in the intestine. Once formed, histamine is stored or rapidly inactivated by its primary degradative enzymes - diamine oxidase (DAO) in the intestine and histamine-N-methyltransferase (HNMT) in the nervous system and lungs.

        It is released in response to allergens, cytokines, stress hormones, alcohol and hormones, and exerts its effects by binding to histamine receptors on basophils, enterochromaffin-like cells, platelets and neurons.

     Histamine intolerance is a toxic response of the body resulting from an imbalance between accumulated histamine and the ability to break it down. It appears to occur primarily as a result of impaired DAO activity, either from gastrointestinal disease or from DAO inhibition, 'blockers' such as alcohol, black tea, green tea and medications. There is also evidence of a genetic predisposition in a subgroup of people with histamine intolerance.