Oat Beta-Glucan Less Effective in Food?

MAASTRICHT, The Netherlands--Oat beta-glucan may not have the same cholesterol-lowering effects when it is used as a food ingredient compared to when it is used as a supplement or in a beverage, according to researchers from Maastricht University. This research, published in the August issue of The American Journal of Clinical Nutrition (78, 2:221-7, 2003) (www.ajcn.org), was released days after the Food and Drug Administration (FDA) adopted a final rule authorizing a health claim for beta-glucan soluble fiber and a reduced risk of coronary heart disease. [More on that story can be found here.]

The Maastricht University researchers conducted two studies. The first investigated the cholesterol-lowering effects of oat beta-glucan in bread and cookies, while the second investigated its effects in orange juice. In the first study, 48 subjects were given control bread and cookies rich in wheat fiber for three weeks. For the next four weeks, 23 subjects were randomly assigned to continue on the control diet while 25 were switched to bread and cookies fortified with oat beta-glucan. Participants had an average intake of 5.9 g/d--where the minimum allowable intake in FDA's health claim is 3 g/d. In the second study, the mean average intake of beta-glucan for the treatment group was 5 g/d. For this study, 25 of the original 48 subjects were given either fiber-fortified orange juice or juice fortified with oat beta-glucan for two weeks. After a one-week washout period, subjects reversed treatments.

In the first study, the change in LDL cholesterol was not significantly different between the groups, while the subjects taking the oat beta-glucan in juice had reduced LDL cholesterol and a decrease in the ratio of total-to-HDL cholesterol. Researchers concluded the food matrix, food processing or both may adversely affect the cholesterol-lowering properties of oat beta-glucan.

"I would agree that the food matrix could possibly have an effect," said John Hunter, director of business development and scientific communications at FutureCeuticals, manufacturer of Nutrim™ oat beta-glucan. "It depends on how the beta-glucan is used because breads and cookies are made with fat or oil. ... What [the researchers] might be seeing is a negative offset because of the sucrose and the fats that are inherent in these formulations. ... If you were to eliminate the fat, my intuition says the study would really [have made] a difference."

According to Hunter, the most effective vehicle for oat beta-glucan is beverages, as demonstrated by the Maastricht study. He noted meal replacement smoothies and milkshake-type drinks are the most effective, although oat beta-glucan can be used in additional applications such as margarine and yogurt. "As a functional food, Nutrim goes into baked goods and pastries quite well, but if you're really looking to impact cholesterol, I don't think that's the best medium," he said. "It's almost an oxymoron if you look at cookies and bread ... to lower your cholesterol."