Modest doses of β-glucan do not reduce concentrations of potentially atherogenic lipoproteins

Abstract

Background: In 1997, the US Food and Drug Administration passed a unique ruling that allowed oat bran to be registered as the first cholesterol- reducing food at a dosage of 3 g β-glucan/d. Objective: The effects of a low dose of oat bran in the background diet only were investigated in volunteers with mild-to-moderate hyperlipidemia. Design: The study was a double-blind, placebo-controlled, randomized, parallel study. Sixty-two healthy men (n = 31) and women (n = 31) were randomly allocated to consume either 20 g oat bran concentrate (OBC; containing 3 g β-glucan) or 20 g wheat bran (control) daily for 8 wk. Fasting blood samples were collected at weeks -1, 0, 4, 8, and 12. A subgroup (n = 17) was studied postprandially after consumption of 2 meals (containing no OBC or wheat bran) at baseline and after supplementation. Fasting plasma samples were analyzed for total cholesterol, HDL cholesterol, triacylglycerol, glucose, and insulin. LDL cholesterol was measured by using the Friedewald formula. The postprandial samples were analyzed for triacylglycerol, glucose, and insulin. Results. No significant difference was observed in fasting plasma cholesterol, LDL, cholesterol, glucose, or insulin between the OBC and wheat-bran groups. HDL-cholesterol concentration fell significantly from weeks 0 to 8 in the OBC group (P = 0.05). There was a significant increase in fasting glucose concentrations after both OBC (P = 0.03) and wheat-bran (P = 0.02) consumption. No significant difference was found between the OBC and wheat-bran groups in any of the postprandial variables measured. Conclusions: A low dosage of β- glucan (3 g/d) did not significantly reduce total cholesterol or LDL cholesterol in volunteers with plasma cholesterol concentrations representative of a middle-aged UK population.