Curcumin potentiates cholesterol-lowering effects of phytosterols in hypercholesterolaemic individuals. A randomised controlled trial

Abstract

Background: Dietary phytosterols (PS) are well-known hypocholesterolaemic agents. Curcumin elicits hypolipidaemic and anti-inflammatory effects in preclinical studies, however, consistent findings in humans are lacking. Objective: Concurrent PS and curcumin supplementation may exhibit enhanced hypocholesterolaemic and anti-inflammatory effects to optimise cardio-protection. The objective of this trial was to investigate the effects of dietary intervention with PS with or without curcumin on blood lipids (primary outcome) in hypercholesterolaemic individuals. Methods: A double-blinded, randomised, placebo-controlled, 2 × 2 factorial trial was conducted in hypercholesterolaemic individuals. Participants received either placebo (PL, no phytosterols or curcumin), phytosterols (PS, 2 g/d), curcumin (CC, 200 mg/d) or a combination of PS and curcumin (PS-CC, 2 g/d–200 mg/d respectively) for four weeks. Primary outcomes included fasting total cholesterol (TC), LDL-cholesterol, HDL-cholesterol, triglycerides (TG), TC-to-HDL-C ratio (TC:HDL-C). Secondary outcomes included anthropometrics and fasting blood glucose concentrations. Results: Seventy participants with a mean (±SEM) fasting TC concentration of 6.57 ± 0.13 mmol/L completed the study (PL, n = 18; PS, n = 17; CC, n = 18; PS-CC, n = 17). PS and PS-CC supplementation significantly lowered TC, LDL-cholesterol and TC:HDL-C post-intervention (p < 0.05). Reductions from baseline in the PS group were 4.8% and 8.1% for TC and LDL-cholesterol respectively (p < 0.05). CC exhibited non-significant reduction (2.3% and 2.6%) in TC and LDL-C respectively, however, the PS-CC resulted in a greater reduction in TC (11.0%) and LDL-cholesterol (14.4%) than either of the treatments alone (p < 0.0001). The reduction in the PS-CC treatment was significantly greater compared to those for CC (p < 0.05) or PL (p < 0.01) alone. Plasma HDL-cholesterol and TG concentrations remained unchanged across all groups. No adverse side effects were reported. Conclusions: The addition of curcumin to phytosterol therapy provides a complementary cholesterol-lowering effect that is larger than phytosterol therapy alone. Implications of these findings include the development of a single functional food containing both the active ingredients for enhanced lipid-lowering and compliance in hypercholesterolaemic individuals. ANZCTR identifier: 1261500095650