Objective: Several studies have indicated that consumption of oat bran lowers blood cholesterol and this effect has been attributed specifically to oat bran's soluble fiber (beta-glucan). This study was designed to test this hypothesis.
Design: The purified fibre (oat gum, 80% beta-glucan) was isolated, and agglomerated in the presence of maltodextrin to facilitate dispersion in a drink. Subjects consumed the oat gum (2.9 g beta-glucan), or maltodextrin placebo, twice daily for 4 weeks, in a randomized, cross-over design with a 3 week wash-out between phases. Consumption was equivalent to a daily dose of about 70 g of oat bran.
Setting: The study was with free-living individuals.
Subjects: Twenty hypercholesterolemic male and female adults entered, and 19 completed, the study.
Interventions: Blood lipids from fasting individuals were measured weekly throughout the study. Diet was monitored using 3 day food diaries.
Results: There were no significant changes (P > 0.05) in blood lipids during the placebo phase. Mean initial total cholesterol (6.76 +/- 0.13 mmol/l) and low density lipoprotein (LDL) cholesterol (4.59 +/- 0.14 mmol/l) levels fell throughout the oat gum phase, and at week 4 each was reduced 9% relative to initial values (P = 0.0004 and 0.005 respectively). When oat gum was discontinued, total and LDL cholesterol returned to initial levels. There were no significant changes in high density lipoprotein (HDL) cholesterol. Triglyceride levels also remained unchanged except for a singular decrease at week 4 of the oat gum phase relative to the initial value, but not compared to the placebo value. The lowered mean total and LDL cholesterol levels occurred in the absence of any dietary changes.
Conclusions: The main component of the soluble fibre of oats, beta-glucan, significantly reduced the total and LDL cholesterol levels of hypercholesterolemic adults without changing HDL cholesterol.