Effects of Dietary Trans Fatty Acids on Mutagenesis of Known Carcinogens

The metabolic activating potential of liver homogenates from animals fed a diet containing 46.6% trans fatty acids or a diet containing less than .1% trans fatty acids was compared in the Ames assay with 2-aminofluorene (AF), benzo(a)pyrene (BP), and dimethylbenz(a)anthracene (DMBA). The control fat had a similar fatty acid composition only consisting of cis fatty acid (cis fats). Since both the cis and trans fats contained moderate levels of saturated fatty acids, a comparison was made between these two fats and corn oil. All three fats were incorporated into high fat, 20%, and low fat, 5%, diets and fed to male Sprague-Dawley rats for three weeks. Although the mutagenic potentials of AF and BP increased with increasing mutagen concentration and with increasing level of dietary fat, there was no consistent difference in mutagenic potential between the cis and trans fats. DMBA was mutagenic only at the two highest concentrations with livers from corn oil-fed rats. The mutagenic activating potential of S-9 from animals fed trans fat diets generally was similar to that of animals fed cis fat diets, but did not follow the trend of animals fed corn oil diets. Thus the amount and/or type of polyunsaturated fatty acids (essential fatty acids) present in the diet may be key factors in evaluating the enhancement of mutagenic activity of DMBA by dietary fat.