Applied nutritional investigationMeta-analysis of the effect of β-glucan intake on blood cholesterol and glucose levels
Introduction
Consumption of soluble fiber from cereals and cereal products has been credited with the ability to promote beneficial human health effects. Cereals such as oats and barley are rich in soluble fibers, e.g., β-glucan. β-Glucan is a non-starch polysaccharide composed of linear chains of glucose with β-(1→3) and β-(1→4) linkages [1]. Oat and barley β-glucan are well recognized for their many health claims and current research is focused on increasing soluble fiber consumption through dietary intervention to address growing consumer awareness. The Food and Drug Administration (FDA) authorizes the use of a health claim on whole grain oat or barley (and derivatives) β-glucan to decrease the risk of coronary heart disease [2], [3].
Epidemiologic studies have reported that the intake of soluble fiber (β-glucan) lowers lipid absorption and in turn decreases the risk of cardiovascular diseases [4]. Consequently, due to its physiologic effects, many researchers have incorporated barley or oat β-glucan into various food products, including breakfast cereals, beverages, bread, and infant foods, to improve the nutritional and health benefits [5], [6], [7], [8]. Many intervention studies have reported a varying degree of effect from β-glucan intake on blood glucose and cholesterol levels, possibly due to variations in study design and sample sizes, thus making it difficult to compare studies and draw any overall conclusions. A meta-analysis is a tool that can aid in resolving these issues.
Meta-analysis is a powerful technique that can synthesize results from different studies by integrating the study, design, sample size, and intervention period and producing a broader generalizability of the overall impact of a treatment [9]. Thus, the purpose of this study was to conduct a meta-analysis to assess the relation between β-glucan consumption from oats and from barley on cholesterol and blood glucose levels (BGLs). The analysis also focused on a continuous dose–response for β-glucan to provide a quantitative evaluation in a standardized format, permitting a numerical analysis across studies.
Section snippets
Study design
The electronic database of Medline (from 1990 through December 2009) was searched using the search terms blood cholesterol, β-glucan or cholesterol, blood glucose, and β-glucan or glycemic and β-glucan limited to humans (male and/or female) and clinical studies (excluding animal and in vitro studies). Only those that were published as full-length articles and in English (language restriction) were considered without any geographic restriction. The reference lists of the retrieved articles were
Quality of the studies
Thirty research articles were chosen; some studies used two or more β-glucan dose levels for oat and barley β-glucan as listed in Tables 1 and 2. Therefore, the meta-analysis included 126 studies based on β-glucan dose levels. Of these 126 studies, 20 studies were selected for the TC and LDL meta-analysis, whereas 18 studies for HDL, 19 studies for TGL/TAG, and 49 studies for blood glucose met the inclusion criteria. Of 126 studies, 82 studies were related to oat β-glucan and the other 44
Discussion
This meta-analysis of 126 studies demonstrates the influence of oat and barley β-glucan consumption on TC, LDL, HDL, TGL/TAG, and BGL in humans. This study also shows a continuous dose–response relation of β-glucan dose (grams per day) on TC and BGL. Significant changes were observed by the meta-analysis for blood cholesterol and glucose with β-glucan consumption. The results of this meta-analysis suggest that oat and barley β-glucan consumption helps lower TC by −0.60 mmol/L, LDL cholesterol
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This project was funded by the Irish Department of Agriculture and Food under the Food Institutional Research Measure as part of the National Development Plan.