Abstract
7-hydroxy-IQ is the major product of the bacterial metabolism of IQ, a potent dietary carcinogen. Yet, unlike IQ, hydroxy-IQ is directly active in the salmonella/microsomal mutagenicity assay. Two subjects consumed a meal of fried meats containing IQ but no detectable hydroxy-IQ. Hydroxy-IQ was isolated from the subjects' faeces collected within 30 h following the fried meat meal; it was absent from the subjects' faeces before and after the meal. This is the first evidence that hydroxy-IQ is formed in humans. Subsequent concern is therefore raised as to its role in the aetiology of colon cancer. From the faeces of one of the subjects a strain was isolated which conformed to the description of a Eubacterium sp. and was capable of producing hydroxy-IQ.