Hypocholesterolemic effect of dietary psyllium in female rats

We fed cholesterol-enriched (1% cholesterol and 0.2% cholic acid) semipurified diets containing either 3% cellulose or psyllium to 2 groups of female Wistar rats for a period of 8 weeks. The feeding of the cholesterol-enriched semipurified diets resulted in a progressive increase in plasma cholesterol levels in both groups during the 8 weeks of the experiment. The rats fed psyllium, however, had significantly lower plasma cholesterol concentrations than the animals fed cellulose throughout the experimental period (at 8 weeks, 8.92 +/- 4.42 and 16.47 +/- 8 mmol/l, respectively, means +/- SD, n = 14, p < 0.01). Most of the plasma cholesterol in both groups at the end of the study was located in the very low-density lipoprotein (VLDL) fraction (91%) and differences in total plasma cholesterol concentrations were predominantly reflected in differences in VLDL cholesterol. Plasma triglyceride concentrations were not significantly different between the 2 groups. Liver cholesterol concentrations paralleled the concentrations of plasma cholesterol and were significantly lower (p < 0.001) in the psyllium-fed rats (90.31 +/- 13.81 micromol/g liver) than in the cellulose-fed rats (60.49 +/- 15.25 micromol/g liver). Substitution of psyllium for cellulose resulted in an increase in the excretion of fecal bile acids by 26%, and this increase was predominantly caused by an increased excretion of beta-muricholic acid and the bile acids derived from beta-muricholic acid (omega-muricholic acid and hyodeoxycholic acid).