The hepatic conversion of some heterocyclic amines to bacterial mutagens is modified by dietary fat and cholesterol.

Groups of Sprague-Dawley rats were fed on diets containing increasing amounts of beef dripping, but having a constant cholesterol content. One group of rats was fed on a diet containing no dripping and no added cholesterol (control). We have studied the ability of individual hepatic S9 preparations to activate the cooked food mutagens 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQX) to bacterial mutagens using Salmonella typhimurium TA98 as indicator. Hepatic preparations from animals fed on a high cholesterol, low-fat diet were less effective in activating the mutagens than preparations from rats fed on the control diet. It was also observed that the capacity of hepatic preparations to activate these mutagens increased as the amount of dripping in the diet increased. These results suggest that it is the triglyceride rather than the cholesterol content of beef dripping which promotes increased mutagen activation capacity in the liver.