Beta-glucan from oats is renowned for its potential to reduce LDL (bad) cholesterol. The FDA allows a health claim on reduced risk of heart disease, while the European Food Safety Authority (EFSA) has published a positive (article 14) health claim on the cause and effect of oat beta-glucan lowering cholesterol. A 13.1 article claim was approved related to maintenance of normal blood LDL-cholesterol concentrations.
Previous meta-analysis have reported that the ingredient may reduce total cholesterol levels by 0.13-0.19 mmol/L, but such analyses did not consider the molecular weight of the oat beta-glucan. A high molecular weight means it can be released from the food matrix during digestion and form a viscous gel inside the small intestine.
Results of the new meta-analysis, published in the American Journal of Clinical Nutrition, indicated that three grams per day of the oat beta-glucan were associated with LDL and total cholesterol reductions of 0.25 mmol/L and 0.30 mmol/L, respectively. Such reductions are between 50 and 100% higher than those published in previous analyses, showing the importance of the molecular weight.
In addition, scientists from Lancaster University (England), the University of Wollongong (Australia), Agriculture and Agri-Food Canada, and the University of Toronto reported that the benefits were observed across different geographies, including Europe, North America, Asia, and Australia, and consumer demographics, including lean, overweight, or obese men and women, with or without type-2 diabetes.
“We found that diets containing [at least] 3 grams of oat beta-glucan per day reduce serum total and LDL cholesterol relative to control by 0.30 and 0.25 mmol/L, respectively, with no effect on HDL cholesterol or triglycerides,” wrote the authors, led by Anne Whitehead from Lancaster University.
“Although generally confirming the results of previous meta-analyses that oat products reduce serum cholesterol, the present results differ in that the magnitude of the effects seen are 50–100% greater than those reported in previous meta-analyses. This is important because our study provides a more accurate assessment of the effect on serum cholesterol of following the recommendations of food standards agencies to consume [at least] 3 grams of oat beta-glucan per day than do previous meta-analyses that included studies in which subjects consumed [less than] 3 grams of oat beta-glucan per day and studies in which oat beta-glucan was more than 95% degraded.”
The meta-analysis was supported by DSM Nutritional Products, which offers the OatWell branded oat beta-glucan ingredient. The ingredient is supported by the Article 14 EFSA health claim.
Whitehead and her co-workers analyzed data from 28 clinical trials published between 1966 and 2013. The data showed that there no significant effect of the size of the dose (3–12.4 g/d) or the duration of the intervention (2-12 weeks) on the results.
“The former suggests that a cholesterol-lowering effect of oats can be achieved with the minimum dose (3 g/d) considered effective by regulatory agencies and that consuming more may not have any additional effect,” they wrote.
The molecular weight of the oat beta-glucan was at least 100 kDa in the studies included in the meta-analysis.
The meta-analysis included studies up to 12 weeks in duration, and Dr Wolever told us that he would like to investigate if the cholesterol-lowering effects are sustained. “If you look at the colonic microbiome and you add new substrates, it can take months to change. It would therefore be of interest to see if the effect gets bigger as time goes on.”
Source: American Journal of Clinical Nutrition
Published online ahead of print, doi: 10.3945/ajcn.114.086108
“Cholesterol-lowering effects of oat b-glucan: a meta-analysis of randomized controlled trials”
Authors: A. Whitehead, E.J. Beck, S. Tosh, T.M.S. Wolever