Objectives:To investigate side by side the effects on serum lipoproteins and postprandial glucose and insulin concentrations of beverages enriched with 5 or 10 g of beta-glucans from oats or barley.Design and setting:An 8-week single blind, controlled study with five parallel groups carried out at two centres under identical conditions.Subjects:A total of 100 free-living hypercholesterolaemic subjects were recruited locally and 89 completed the study.Interventions:During a 3-week run-in period all subjects consumed a control beverage. For the following 5-week period four groups received a beverage with 5 or 10 g beta-glucans from oats or barley and one group continued with the control beverage. Blood samples in weeks 0, 2, 3, 7 and 8 were analysed for serum lipids, lipoproteins, glucose and insulin. Postprandial concentrations of glucose and insulin were compared between control and the beverage with 5 g of beta-glucans from oats or barley.Results:Compared to control, 5 g of beta-glucans from oats significantly lowered total-cholesterol by 7.4% (P<0.01), and postprandial concentrations of glucose (30 min, P=0.005) and insulin (30 min, P=0.025). The beverage with 10 g of beta-glucans from oats did not affect serum lipids significantly in comparison with control. No statistically significant effects compared to control of the beverages with barley beta-glucans were found.Conclusions:A daily consumption of 5 g of oat beta-glucans in a beverage improved the lipid and glucose metabolism, while barley beta-glucans did not.Sponsorship:Founded by the European Commission (QLK1-CT-2000-00535).European Journal of Clinical Nutrition advance online publication, 13 July 2005; doi:10.1038/sj.ejcn.1602240.