More support for beta-glucan against high cholesterol levels
significantly lowered cholesterol levels in high-risk patients,
says a new randomised interventional trial.
Beta-glucan, a non-starch polysaccharide found in oats, has been the subject of increasing attention with some reports showing the soluble fibre can decrease LDL-C levels. The new study, published on-line in the Nutrition Journal, adds to this body of science, reporting that a daily dose of six grams of concentrated oat beta-glucan for six weeks significantly reduced total and LDL cholesterol in subjects with elevated cholesterol. High cholesterol levels, hypercholesterolaemia, have a long association with many diseases, particularly cardiovascular disease (CVD), the cause of almost 50 per cent of deaths in Europe, and reported to cost the EU economy an estimated €169bn ($202bn) per year. Researchers from the University of Minnesota, led by Joanne Slavin, recruited 75 healthy men and women with elevated cholesterol levels and randomly assigned them to receive either a daily dose of concentrated oat beta-glucan (6 grams per day) or the same dose of dextrose (control). Blood samples were taken at the start of the intervention period, at the half-way point and at the end (six weeks), and analysed for total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, glucose, insulin, homocysteine and C-reactive protein (CRP). Slavin and co-workers report than consumption of the oat beta-glucan produced a significant reduction in total cholesterol (0.3 mmol/L) and LDL cholesterol (0.3 mmol/L), compared to the start of the study. "The decrease in LDL cholesterol as a result of concentrated oat beta-glucan administration is large enough to be clinically relevant," they wrote. "A 0.26 mmol/L increase in LDL cholesterol results in a 12 per cent increase in risk of CVD." No significant changes were observed in HDL cholesterol, glucose, insulin, homocysteine or C-reactive protein (CRP) as a result of either the beta-glucan or control interventions. To further understand the biochemistry of the soluble fibre, the researchers compared the fermentability of the concentrated oat beta-glucan with inulin and guar gum using a model intestinal fermentation system. It has been reported that fermentation products like propionate and acetate may suppress cholesterol synthesis and contribute to cholesterol lowering. The researchers found that all three produced similar concentrations of short chain fatty acids (SCFA) and acetate. On the other hand, fermentation of the oat beta-glucan was found to produce the highest concentrations of butyrate at 4, 8, and 12 hours, after which inulin produced the most. "Thus, a practical dose of oat beta-glucan can significantly lower serum lipids in a high-risk population and may improve colon health," they said. Based on these positive results, the researchers concluded that concentrated oat beta-glucan would be suitable as a "stand-alone" supplement for cholesterol reduction. "This product could also be used as a food ingredient to increase fibre content of food," wrote Slavin and co-workers. "When incorporated into minimally processed, low-fat food, concentrated oat beta-glucan is hypothesised to retain its hypocholesterolaemic effects." Source: Nutrition Journal 26 March 2007, 6:6, doi:10.1186/1475-2891-6-6 "Concentrated oat beta-glucan, a fermentable fiber, lowers serum cholesterol in hypercholesterolemic adults in a randomized controlled trial" Authors: K.M. Queenan, M.L. Stewart, K.N. Smith, W. Thomas, R.G. Fulcher and J.L. Slavin
