It is interesting that eating of histamine-containing fish may cause stronger toxic effects than peroral administration of the same amount of pure histamine. The latter is largely metabolized during absorption through the intestinal wall or in the liver, and even at high doses will cause relatively weak effects. There is hypothesis that scombroid poisoning is caused either by oxogenous histamine potentiated by the other biogenic vasoactive amines and maybe by other toxicants or by endogenous histamine, releases from the stem cells by the influence of some still unknown substances formed during the fish putrefaction process. Actually, scombroid poisoning may take place upon eating any food containing amino acids necessary for the synthesis of biogenic amines and which is contaminated by suitable bacteria.