Beta-Glucan Key to Cardiovascular Health Benefits

May 02, 2000

New York (MedscapeWire) May 2 Two research studies presented at the Experimental Biology 2000 meeting indicate that eating foods rich in beta-glucan, the kind of soluble fiber found in oatmeal and barley, can help to control appetite by increasing the feeling of fullness.  In the first study, Joseph Keenan, MD, of the University of Minnesota Medical School in Minneapolis, found that barley had a significant positive effect on satiety. Dr. Keenan divided 60 mildly overweight men and women with elevated cholesterol levels (more than 240 mg) into 3 groups. For 4 weeks, each group followed the National Cholesterol Education Program's Step I diet, supplemented with muffins containing different types of fiber. Subjects in the first group were given muffins rich in barley endosperm, which contained 7 g of beta-glucan in an easily absorbable form. A second group was given muffins rich in barley bran, which also contained beta-glucan (5 g), but in a form less easily absorbed by the body. The third group ate muffins made of refined wheat flour, which were low in fiber and contained no beta-glucan. All participants were asked to rank their feelings of fullness, hunger, and satiety before, during, and directly after the study.

The groups who ate muffins high in soluble fiber felt significantly fuller and more satisfied throughout the study than those who ate the wheat muffins. "We attribute the improvement in satiety almost entirely to the beta-glucan. Foods rich in beta-glucan stay in the stomach for a longer period of time compared to foods low in this fiber. That leads to a feeling of fullness, or satiety," said Dr. Keenan.

Satiety levels also reflected a change in body weight. Dr. Keenan reported a trend toward weight loss, with an average decrease of half a pound per week among those who ate the barley, while those who ate the wheat gained half a pound per week.

Dr. Keenan's research confirms the results of a second study, presented by Allan Geliebter, PhD, of the New York Obesity Research Center at St. Luke's-Roosevelt Hospital. In that study, Dr. Geliebter's comparison of a high soluble-fiber oatmeal breakfast and a nonfiber sugared corn flakes breakfast, containing equal calories, showed improved satiety from oatmeal. When participants ate oatmeal for breakfast, they consumed 30% fewer calories at lunch, compared with those who ate sugared corn flakes for breakfast.

Dr. Geliebter's data help to explain the mechanism behind the earlier study's results. According to Dr. Geliebter, "The effect may be due primarily to a delay in gastric emptying, the time it takes for oatmeal to leave the stomach and enter the blood as glucose and other nutrients. The slower the stomach empties the longer food stays in the stomach and the longer people feel full and satisfied." Slower gastric emptying can stabilize blood sugar levels and communicate stabilized and prolonged appetite signals to the brain.

The results of these studies show that soluble fiber can play an important role in reducing the risk of cardiovascular disease by controlling 2 risk factors: obesity via the satiety effect and high cholesterol via the reduction in both total and low-density lipoprotein (LDL) cholesterol; many previous studies have shown that soluble fiber-rich oatmeal can lower cholesterol.Similarly, Dr. Keenan's study showed that those who consumed the beta-glucan-rich muffins had significantly reduced total cholesterol (11%) and LDL cholesterol (12%), while high-density lipoprotein cholesterol levels remained unchanged. "This is a very significant result," said Dr. Keenan. "Such reductions are estimated to produce a 20% reduction in the risk of developing heart disease."