Influence of dietary fat on fecal mutagenicity in premenopausal women

A dietary intervention study was conducted on 31 premenopausal women (age: 20-40 years) to investigate the relationship between dietary fat and fecal mutagenicity. After a free-living period (baseline) of one menstrual cycle, the subjects were placed on a high-fat diet (40% calories from fat) for 4 menstrual cycles, followed by a low-fat diet (20% calories from fat) for 4 menstrual cycles. One-half of the subjects were randomly assigned throughout the study to a diet with a P:S ratio of 1.0 while the other half was assigned to one with a P:S ratio of 0.3; body weight by group remained constant. Three-day stool samples were collected at the mid-follicular period during the free-living phase and during the 4th menstrual cycle of each of the 2 controlled diet periods. Mutagenicity was assayed by the SOS chromotest. Reduction of dietary fat was accompanied by a significant decrease in fecal mutagenicity in both P:S groups. Combined values, i.e., both P:S groups, were 20.3 units for high-fat diets vs. 8.78 for low-fat diets.