High molecular weight oat β-glucan enhances lipid-lowering effects of phytosterols. A randomised controlled trial

Abstract

Oat β-glucan (OBG) and phytosterols (PS) are known to lower blood cholesterol levels via different mechanisms. Combination of high molecular weight (MW) OBG and PS in a single functional food could have complementary and/or synergistic effects for optimising heart health. The aim of this study was to investigate the effects of dietary supplementation with high-MW OBG with or without PS on plasma lipids in hypercholesterolaemic individuals. In a double-blinded, placebo-controlled, 2×2 factorial trial, participants were randomised to receive biscuits fortified with either no PS or OBG (PL, n=18) or 2g PS (PS, n=18), 3g OBG (OBG, n=18), or combination of 2g PS and 3g OBG (PS-OBG, n=18) per day for 6 weeks. Primary outcome was fasting plasma total cholesterol (TC) and secondary outcomes were LDL-cholesterol, LDL-C; HDL-cholesterol, HDL-C; triglycerides, TG and TC to HDL-cholesterol (TC:HDL) ratio. TC and LDL-C were significantly lowered following PS (-4.6% and-7.6% respectively; p<0.05), OBG (-5.7% and-8.6%; p<0.01) and PS-OBG (-11.5% and-13.9%; p<0.0001) administration. The reduction in TC in the PS-OBG group was significantly greater compared to PL (p<0.001) and PS (p<0.05). PS-OBG group had a significantly greater reduction in LDL-C compared to PL (p<0.01) but not in comparison to PS or OBG groups. TC:HDL ratio was significantly reduced following PS-OBG (-8.9%; p<0.01) only, and there was no significant difference found between groups. Plasma TG reduced by 8.4% following PS-OBG, however, this was statistically non-significant. Plasma HDL-C remained unchanged across all groups. Dietary supplementation with high-MW OBG and PS in a single functional food enhances their lipid-lowering potential. Blood cholesterol lowering by PS and OBG is additive. Delivery of these two bioactive nutrients in a single food allows optimisation of their lipid-lowering effects and may provide added heart health benefits with enhanced compliance. The trial was registered with the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au/(ACTRN12618001455257).