β-SITOSTEROL DECREASES BUT ITS INTAKE FREQUENCY HAS NO EFFECT ON PLASMA CHOLESTEROL LEVEL.

It has been shown that dietary phytosterols intake is inversely related to plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) concentrations. The present study investigated effect of β-sitosterol intake frequency on plasma lipoprotein profile and the gene expression of transporters, receptors and enzymes involved in cholesterol metabolism. Thirty-three hamsters were divided into three groups with the control hamsters being gavage-administrated 3 mg cholesterol 3 times per day, whereas the second group being gavage-administered 3 mg β-sitosterol with 3 mg cholesterol 3 times per day (S-3) and the third group being gavage-administered 9 mg β-sitosterol with 3 mg cholesterol for one time and 3 mg cholesterol for the other two times per day (S-1). Results demonstrated that compared with the control group, hamsters gavage-fed β-sitosterol had a significant decrease in plasma TC and non-high density lipoprotein cholesterol (Non- HDL-C) concentration, but there was no significant difference between S-3 and S-1 groups. Real time PCR analysis revealed that the cholesterol-lowering activity of β-sitosterol was mediated by its inhibition on the intestinal cholesterol absorption with up- regulation of Niemann-Pick C1 like 1 (NPC1L1), ATP binding cassette transporters 5 and 8 (ABCG5/8) and microsomal triacylglycerol transport protein (MTP), but no significant difference was found between S-3 and S-1 groups. It was concluded that β-sitosterol was effective in reducing plasma cholesterol level and for a given dose of β-sitosterol, the administration frequency had no effect on plasma lipoprotein profiles. [ABSTRACT FROM AUTHOR]