Hypocholesterolemic activity of buckwheat flour is mediated by increasing sterol excretion and down-regulation of intestinal NPC1L1 and ACAT2

Interest in Tartary buckwheat as a cholesterol-lowering functional food is increasing. The present study was to (i) investigate the relative hypocholesterolemic activity of Tartary buckwheat flour compared with that of wheat and rice flour; and (ii) study the interaction of these three flours with gene expression of sterol transporters and proteins involved in cholesterol absorption. Thirty-six male hamsters were divided into four groups fed either the control or one of three experimental diets containing 24% respective flour, for a period of 6 weeks. Results showed that Tartary buckwheat flour but no wheat and rice flours reduced plasma total cholesterol (TC) and non-high-density lipoprotein cholesterol (non-HDL) as well as hepatic cholesterol concentrations. Compared with that of wheat and rice flours, supplementation of Tartary buckwheat flour into diet led to greater neutral sterol excretion and lesser mRNA of intestinal Niemann-Pick C1 Like 1 (NPC1L1) and acyl-CoA: cholesterol acyltransferase 2 (ACAT2). It was therefore concluded that Tartary buckwheat flour was hypocholesterolemic via inhibition of cholesterol absorption, most likely mediated by down-regulation of intestinal NPC1L1 and ACAT2.