Cholesterol-Lowering Effects of Oat β-Glucan.

Elevated total and low-density lipoprotein (LDL) cholesterol levels are considered major risk factors for cardiovascular disease.

Lifestyle modifications to reduce cardiovascular disease risk include the recommendation to increase consumption of viscous soluble dietary fiber to lower LDL cholesterol.

Oat β-glucan, a soluble dietary fiber that is found in the endosperm cell walls of oats, has generated considerable interest due to its cholesterol-lowering properties.

Several regulatory bodies have approved a health claim on the cholesterol-lowering effects of oat β-glucan at levels of 3.0 gram daily

The United States Food and Drug Administration (FDA) approved a health claim for β-glucan soluble fiber from oats for reducing plasma cholesterol levels and risk of heart disease in 1997. Similarly, our Ministry of Health together the United Kingdom Joint Health Claims Initiative (JHCI) and the European Food Safety Authority allowed a cholesterol-lowering health claim for oat β-glucan.

Clinical evidence for the cholesterol lowering effects of β-glucan soluble fiber comes from over 1400 studies ranging over 40 years.

Most recent ones include the study by Karen Charlton et al on the effect of β-glucan-rich oat products on cholesterol levels in mildly hypercholesterolaemic overweight adults which was reported in the August 2011 issue of the British Journal of Nutrition (1).

The ability of oat β-glucan to reduce serum cholesterol depends on its ability to increase the viscosity of intestinal contents. The viscosity of β-glucan solutions is determined by its molecular weight (MW) and solubility, both of which can be altered by normal methods of processing and storage.

Putative effects have been attributed to an influence on the sequestering of bile acids in the gut, reducing re-absorption and return to the liver for further synthesis. This reduces the amount of bile acids returning to the liver and forces the liver to produce more bile acids to replace the bile acids lost in the stool. In order to produce more bile acids, the liver converts more cholesterol into bile acids, which lowers the level of cholesterol in the blood (2).

Oat β-glucan has been shown to decrease postprandial plasma glucose and serum insulin responses (3). To help lower the rise of blood glucose, the Minsitry of Health recommends that Oat β-glucan be taken on its own and not together with other food.

Oat β-glucan is also know to increase immune function and decrease risk of infection (4).

References:

1. Charlton KE, Tapsell LC, Batterham MJ, O'Shea J, Thorne R, Beck E, Tosh SM. Effect of 6 weeks' consumption of β-glucan-rich oat products on cholesterol levels in mildly hypercholesterolaemic overweight adults. Br J Nutr. 2011 Aug 3:1-11. [Epub ahead of print] You can refer to the full text HERE

2. Wolever TMS, Tosh SM, Gibbs AL, et al. (2010) Physicochemical properties of oat {beta}-glucan influence its ability to reduce serum LDL cholesterol in humans: a randomized clinical trial. Am J Clin Nutr 92, 723–732. You can refer to the full text HERE

3. Juvonen KR, Salmenkallio-Marttila M, Lyly M, Liukkonen KH, Lähteenmäki L, Laaksonen DE, Uusitupa MI, Herzig KH, Poutanen KS, Karhunen LJ. Semisolid meal enriched in oat bran decreases plasma glucose and insulin levels, but does not change gastrointestinal peptide responses or short-term appetite in healthy subjects. Nutr Metab Cardiovasc Dis. 2011 Sep;21(9):748-56. Epub 2010 Jun 4.

4. Davis JM, Murphy EA, Brown AS, Carmichael MD, Ghaffar A, Mayer EP. Effects of moderate exercise and oat beta-glucan on innate immune function and susceptibility to respiratory infection. Am J Physiol Regul Integr Comp Physiol. 2004 Feb;286(2):R366-72.