Dietary taurine or glycine supplementation reduces plasma and liver cholesterol and triglyceride concentrations in rats fed a cholesterol-free diet

The effects of dietary supplementation of taurine or glycine, the two amino acids involved in bile acid conjugation in the liver, on plasma and hepatic lipid concentrations were evaluated in rats fed a cholesterol-free diet. Three groups of male rats (140~150g) were fed a cholesterol-free diet (CFD), a taurine-supplemented diet (TSD; CFD + 1.5% taurine) or a glycine- supplemented diet (GSD; CFD + 1.5%o glycine) for 5 weeks. There was no significant difference in organ weights and cumulative body weight gain between groups at the end of the experimental period. Plasma triglyceride level was significantly lower in rats fed the TSD (53% decrease, P<0.001) compared to those fed the CFD. Both TSD and GSD significantly lowered the plasma levels of total cholesterol (40% decrease in TSD, p<0.001 and 27% decrease in GSD, p<0.001, respectively) and LDL-plus VLDL-cholesterol (50% decrease in TSD, p<0.05 and 39% decrease in GSD, p<0.01, respectively) compared to the values for CFD. Liver cholesterol concentration was not significantly influenced by the dietary supplementation of taurine or glycine. However, both TSD and GSD showed significantly lower hepatic triglyceride concentrations (43% and 53% decreases in TSD and GSD, p<0.001, respectively), and elevated hepatic free fatty acid levels (77% increases in both groups, p<0.001) compared to the values for CFD. These results suggest the possible roles of dietary taurine or glycine as hypocholesterolemic and/or hypotriglyceridemic agents.