Histamine is one of the biogene amines.
They are produced by decarboxylating amino acids. Decarboxylating enzymes are active in various plant or animal tissues. Biogene amines are naturally occuring substances preserving tissues as well as functions in higher organisms, thus, they normally are easily metabolized and usually they are well tolerated if contained in food. If concentrations of amines exceed normal levels, possibly due to bacterial contamination of food, harmful effects may occur. Natural mechanisms of detoxification, for example due to amino oxidase, that catalyses oxidative deamination, may have non-sufficient activity, if histamine is taken up in high amounts.