Cholesterol-lowering effects of oat β-glucan

Several soluble polysaccharides have been shown to have cholesterol-lowering properties and to have a role in prevention of heart disease. Oats provide one of the richest sources of the dietary soluble fiber β -glucan, providing 5.0 g (oatmeal) to 7.2g (oat bran) per 100 g serving. Both are also valuable sources of total dietary fiber, which ranges from 9.9-14.9 g per 100 g serving. Oats have recently gained considerable interest as a rich source of β -glucan with cholesterol-lowering properties.

 In March 1995, the Quaker Oats company submitted a petition to the FDA stating that consumption of whole oat products (oats, oat bran, and oat flour) decreases total cholesterol and LDL cholesterol concentrations and reduces the risk of CHD.

In February 2003 Creanutrition and its parent company Swedish Oat Fiber submitted a scientific dossier for oat β -glucan and blood cholesterol to the JHCI in the United Kingdom. In May 2004, the JHCI approved a generic health claim for oat β -glucan and blood cholesterol based on the totality of the evidence. The health claim states that the inclusion of at least 3 g/day of oat β-glucan as part of a diet low in saturated fat and a healthy lifestyle can help reduce blood cholesterol.

The benefits for lowering lipids with oats and oat-based products have been reported in animal and human studies. Oat gum soluble fibre has been reported to exert a greater hypocholesterolaemic effect than several other fibers tested and found to be similar to that of cholestyramine.

According to the study, soluble fiber from oat products, psyllium, pectin, and guar gum each significantly lowered total cholesterol. One gram of soluble fiber from oats, psyllium, pectin, or guar gum produced changes in total cholesterol of -0.037, -0.028, -0.070, and -0.026 mmol/L (-1.42, -1.10, -2.69, and -1.13mg/dL), respectively, and in LDL cholesterol of -0.032, -0.029, -0.055, and -0.033 mmol/L (-1.23, -1.11, -1.96, and -1.20 mg/dL), respectively. (The American Journal of Clinical Nutrition, Volume 69, Issue 1, 1 January 1999, Pages 30–42).

 A number of studies indicate that β -glucan is the major active cholesterol-reducing component of oats. When β -glucans are fed in a dose-dependent manner, significantly greater reductions in blood cholesterol are observed as β -glucan content increases. Furthermore, treatment of oats with enzymes that destroy β -glucan results in a loss of cholesterol-lowering potential of oats.
Cholesterol-lowering effects of oat β-glucan

What is β-glucan?

β-glucan is found in every living organism. It is a linear polysaccharide made up entirely of sequences of (1à4) linked D-glucopyranosyl units separated by single (1à3)- β-linked unit.

They are carbohydrates consisting of linked glucose molecule with a molecular mass between 50 and 2,300 kDa.

β-glucan is a cell wall polysaccharide constituent found in the endosperm and in the subaleurone layer of oats and barley.

The typical range of β-glucan in oat bran is from 5.5 to 9.0 percent and in barley bran from 4.0 to 8.5 percent.

These cell wall molecules are very large, water soluble, and produce viscous worts if not sufficiently reduced in size by hydrolysis.

The soluble fiber content of oat, especially β-glucan, like many other polysaccharides is generally believed to be responsible for its beneficial effect on cardiovascular disease and certain cancer.

Some studies have suggested that some health promotion capabilities of oats are due to its antioxidants as well as β-glucan.

Oat bran and oat products have captured the attention of both industry and the scientific community because the soluble β-glucans abundant in oat bran have been shown to have cholesterol effects in rats and humans. It may reduce total and low density lipoprotein (LDL) cholesterol, thereby reducing the risk of coronary heart disease.
What is β-glucan?