Beta-Glucan in Oats Lowers Blood Cholesterol
~ October 1998 No.52 ~
Adding fiber to the diet has become almost an obsession for many who were looking to eat smart and live healthy. But the fiber story became clouded when conflicting results were published in the scientific literature, particularly related to the effect of fiber on blood cholesterol levels. Studies - often with apparently the same protocols - were producing positive, negative and no effect on lowering plasma cholesterol. For a while it wasn’;t clear whether dietary fiber could reduce cholesterol levels or not.
The term fiber is not an exact one and food scientists still argue about what is fiber, what makes up its various sub-fractions and how it is measured. Fiber in foods can be divided first into soluble and insoluble forms depending on how they dissolve in water, usually hot water.
It turns out that soluble fiber is the active agent that reduces blood cholesterol in humans. Detailed analyses of the soluble fiber in oats has shown that it is the beta-glucan that is giving the fiber its cholesterol lowering effect. The United States Food and Drug Administration recently announced that it would allow a health claim to be made for foods containing oat bran, oat flour or rolled oats because of the level of soluble fiber in the form of beta-glucan these foods contain. They concluded that based on scientific evidence, oats could lower blood cholesterol levels. The levels of low -density lipoproteins appear to be affected, but not the high-density fraction.
Beta-glucan is the component of soluble fiber common in oats that can be separated from the oat grain by selective milling. Beta-glucan is a type of cellulose that has a molecular weight of 1.5 to 2.0 million depending on the grain from which it is derived. Beta-glucan gets its unique properties from the two types of chemical bond linkages found in the large molecule. Although oats are the best source of beta-glucan, barley and rice also contain them.
Adding beta-glucan to the diet has been shown to reduce blood cholesterol levels by up to 10%. However, like many foods that are good for your health, when the subjects stopped consuming the beta-glucans, their blood cholesterol returned to pre-experiment levels.
Nutrition Journal 2007, 6:6