Effect of dietary trans fatty acids on microsomal enzymes and membranes.

Three groups of rats were maintained on diets containing different proportions of trans fatty acids (0, 18.3 or 36.6% of the total fatty acids) for eight weeks. No differences in body weight were observed among the three groups, but the fat cell size, determined in epididymal fat, differed significantly between the controls and the rats fed diets containing trans fatty acids. The supernatant obtained by centrifuging homogenates of liver from the rats at 9000 X g (S-9 fraction) was used as an activator in a bacterial test for mutagenicity of 2-aminofluorene and aflatoxin B1 using Salmonella typhimurium strains TA 98 and TA 100, respectively. The mutagenicities of 2-aminofluorene in strain TA 98 and of aflatoxin B1 in strain TA 100 were significantly lower with the liver S-9 fraction from rats fed a diet containing 36.6% trans fatty acids than with the liver S-9 fraction from rats fed a control diet with no trans fatty acids.