The effect of heated fat on the carcinogenic activity of 2-acetylaminofluorene.

Summary Fresh or heated vegetable oils from various sources were fed to rats per se or with specific levels of 2-acetylaminofluorene (AAF) for periods of from 9 to 30 months. The heated oils were obtained from commercial sources or were prepared under controlled laboratory conditions. A heated oil, similar in properties to a commercial crystallization inhibitor, was subjected to digestion with lipase or divided into urea adduct and nonurea adduct-forming fractions. The results indicated that the lipase-undigestible or the nonurea adduct-forming fraction isolated from heated oil acted in synergism with AAF and enhanced its carcinogenic activity. All the animals fed .005 per cent AAF and a mixture of 7.5 per cent fresh corn oil and 2.5 per cent of the lipase-undigestible or 2.5 per cent of the nonurea adduct-forming fraction isolated from heated oil developed malignant tumors, and none survived the 30-month experimental period. None of the animals fed .005 per cent AAF and 10 per cent fresh corn oil developed malignant tumors, and all survived. Whether heated oil as such enhanced the carcinogenic activity of AAF could not be demonstrated at lower than the 5 per cent error level in the present study. However, heated oils prepared under controlled laboratory conditions were no more co-carcinogenic than heated oils obtained from commercial frying operations. The observations that the co-carcinogenic effect of heated oil could best be demonstrated when fractions of heated oil were fed with fresh oil may be of significance to the human diet, since such an experimental system reflects present culinary practice.