NEW YORK (Reuters Health) Mar 31 - The soluble fiber beta-glucan added to a fruit drink lowers serum concentrations of total and LDL cholesterol, according to results of a study published in the March issue of the American Journal of Clinical Nutrition.

Dr. Ronald P. Mensink, of Maastricht University, the Netherlands, studied the effects of a daily fruit drink that provided 5 g rice starch (placebo; n = 22) or beta-glucan from oats (n = 25) in healthy subjects over period of 5 weeks.

Blood samples were obtained at the end of a 3-week run-in period and the end of intervention to measure lipids and lipoproteins, fat-soluble antioxidants, and non-cholesterol sterols -- sitosterol and campesterol as markers of cholesterol absorption, and lathosterol to evaluate cholesterol synthesis.

"Compared with the changes in the control group, the changes in serum concentrations of total and LDL cholesterol in the beta-glucan group were -0.30 mmol/L or -4.8% for total cholesterol and -0.31 mmol/L or -7.7% for LDL cholesterol," Dr. Mensink's team reports.

The differences between the control and beta-glucan groups in the change in serum concentrations of lathosterol and sitosterol were -13% (p = 0.023) and -11% (p = 0.030), respectively. There were no significant effects observed on fat-soluble antioxidants.

The authors note that the reason beta-glucan lowers serum LDL-cholesterol concentrations is not known. One possible mechanism is that beta-glucan binds bile acids or increases intestinal viscosity. This results in a decreased reabsorption of bile acids and increased fecal bile acid excretion. As a result, there is an increase in bile acid synthesis and excretion in the intestine. Hepatic cholesterol synthesis increases at the same time due to a greater need for cholesterol in the liver for bile acid production.