HDL biology
Psyllium fiber lowers CETP activity 18% regardless of sex, while its triglyceride effects diverge by sex and menopausal status (Am J Clin Nutr 2001)
Original title: Sex and hormonal status influence plasma lipid responses to psyllium
In a 30-day crossover trial, 24 men, 23 premenopausal women, and 21 postmenopausal women received 15 g/day psyllium or control. Psyllium lowered LDL-cholesterol 7-9% (P<0.0001) without affecting HDL-cholesterol, and its effect on triglycerides depended on sex and hormonal status: triglycerides fell 17% in men and rose 16% in postmenopausal women (P<0.01), with no significant change in premenopausal women. LCAT activity was unaffected by psyllium, but CETP activity was 18% lower after psyllium than after control (P<0.0001), a uniform effect not reported to differ by sex or hormonal status. The results indicate psyllium's intestinal action indirectly alters intravascular lipoprotein processing, with some effects sex- and hormone-dependent and others, like CETP suppression, more general.
Original abstract
Background: The primary mechanisms by which soluble fiber lowers plasma cholesterol are well known. However, specific effects of fiber on lipoprotein metabolism and how sex and hormonal status influence these effects are not well defined.
Objective: The effects of a psyllium supplement in men, premenopausal women, and postmenopausal women were examined to determine the mechanisms by which psyllium lowers plasma LDL-cholesterol concentrations and affects lipoprotein remodeling in the intravascular compartment.
Design: We designed a crossover trial in which 24 men, 23 premenopausal women, and 21 postmenopausal women were randomly assigned for 30 d to a fiber supplement (15 g psyllium/d) or a control. Plasma lipids and cholesteryl ester transfer protein and lecithin-cholesterol acyltransferase (phosphatidylcholine-sterol O-acyltransferase) activities were measured after each treatment.
Results: When compared with the control, psyllium intake lowered plasma LDL-cholesterol concentrations by 7-9% (P < 0.0001) without affecting plasma HDL-cholesterol concentrations. An interactive effect between fiber and sex and hormonal status was observed for plasma triacylglycerol. Psyllium supplementation significantly lowered plasma triacylglycerol concentrations in men by 17% and raised triacylglycerol concentrations in postmenopausal women by 16% (P < 0.01). The dietary treatment did not significantly affect plasma triacylglycerol in premenopausal women. Lecithin-cholesterol acyltransferase was unaffected by psyllium intake whereas cholesteryl ester transfer protein activity was 18% lower after psyllium supplementation than after the control treatment (P < 0.0001).
Conclusions: This trial showed that the psyllium-induced responses to plasma lipids were associated with sex and hormonal status and that psyllium, through its action in the intestinal lumen, indirectly affected the intravascular processing of lipoproteins.
Summary written by cetpinhibition.org from the published abstract; figures as published. Page updated 19 August 2026. Methods.