G.I. Hist Support is a formula designed to assist patients who have trouble processing external sources of histamine-rich foods and nutritional elements. This formula is especially helpful for those with genetic weaknesses in A01C (Diamine Oxidase), the main enzyme responsible for the degradation of ingested histamine. A key active ingredient in G.I. Hist Support is porcine-derived diamine oxidase (DAO), and research suggests that DAO derived from porcine kidney appears to have identical action to DAO derived from porcine intestine. Along with 5 other ingredients shown to support allergy relief, GI Hist is one of the best supplements on the market that includes key cofactors along with high dose DAO.