[Dietary lipids and variations of fecal output and metabolic components in rats]

The amount of feces (g/day) and the concentration of fecal secondary bile acids have been measured in ninety-six male Wistar rats C.P.B.: W.U. which received diets varying in their content both in linoleic acid and in total fat (5-10-20 p. 100). The fecal outflow, water excretion and fecal concentration of deoxycholic and lithocholic acids increased exponentially with time of feeding. As early as two weeks after beginning the diets, the increases were significantly greater for the diet with saturated fatty acids than for the diet with polyunsaturated fatty acids. The amount of ingested fat had only a slow influence on fecal metabolic factors. Indeed, the effect of the diet with the highest fat content became significantly different from that of the diet with the lowest fat content only after seven weeks of feeding. The existence of a linear relationship between secondary bile acid concentrations and both fecal water outflow and fresh fecal outflow would seem to indicate that the increase in bile salt fecal excretion was strictly physiological. The proposed experimental protocol can be applied to study the relationship between fat intake, bile acid fecal excretion and tumor yield in experimental colonic tumorigenesis initiated by 1,2-dimethyl-hydrazine.