Effect of beta-glucan level in oat fiber extracts on blood lipids in men and women

Objective: An active hypolipidemic component in oats, the soluble fiber beta-glucan, has been concentrated in an oat fiber extract. The oat fiber extract has been used to replace fat in food products. This study was designed to determine if moderate levels of oat fiber extract could be incorporated into a typical diet and whether plasma lipids could be reduced by the amount of beta-glucan added to the diet. Methods: Oat fiber extracts containing low (1% by weight) or high (10% by weight) beta-glucan were fed to 23 mildly hypercholesterolemic subjects (seven men and 16 women). A maintenance diet was fed for 1 week followed by diets containing an oat extract for 5 weeks each in a crossover pattern. Five percent of the energy from fat in the maintenance diet was replaced with the oat extract in the experimental diets. Caloric intake was adjusted to try to maintain each subject's initial weight. Fasting blood was collected several days apart after separate 12 hour fasts the end of each period. Plasma was analyzed for triglycerides, total cholesterol, and Lipoprotein cholesterol fractions. Results: HDL, HDL(2), and VLDL cholesterol, and triglyceride levels after the oat extract diets were not significantly different from those after the maintenance diet. Total and LDL cholesterol levels decreased significantly (p < 0.001) from maintenance levels after both diets containing the oat extracts. Total cholesterol levels after the higher beta-glucan extract diet were significantly lower than those after the low beta-glucan diet. Conclusions: Beneficial reduction of cholesterol was obtained with modest amounts of oat extract incorporated into the diet. A significant dose response due to beta-glucan concentration in the oat extract was observed in total cholesterol levels.