Elsevier

Nutrition

Volume 27, Issue 10, October 2011, Pages 1008-1016
Nutrition

Applied nutritional investigation
Meta-analysis of the effect of β-glucan intake on blood cholesterol and glucose levels

https://doi.org/10.1016/j.nut.2010.11.006Get rights and content

Abstract

Objective

A meta-analysis was performed on epidemiologic studies to assess the relation between β-glucan consumption from oats and from barley on blood cholesterol level, triglyceride/triacylglycerol (TGL/TAG) level, and blood glucose level (BGL) in humans. In addition, the effect of β-glucan on total cholesterol (TC) and BGL was translated into an empirical dose–response model.

Methods

Thirty research articles that evaluated the effect of different exposure levels of β-glucan on blood cholesterol and BGL were analyzed, yielding 126 clinical studies.

Results

There was a significant inverse relation in TC (−0.60 mmol/L, 95% confidence interval [CI] −0.85 to −0.34), low-density lipoprotein (−0.66 mmol/L, 95% CI −0.96 to −0.36), and TGL/TAG (−0.04 mmol/L, 95% CI −0.15 to 0.07) after consumption of β-glucan. In contrast, an increase in high-density lipoprotein cholesterol was noted (0.03 mmol/L, 95% CI −0.06 to 0.13) with the random-effect model. The analysis showed a significant change in BGL (−2.58 mmol/L, 95% CI −3.22 to −1.84) with high heterogeneity between (I2 = 97%) and across (τ2 = 5.88) the studies. The fixed-effect model showed a significant change in TC, low-density lipoprotein, and BGL, whereas it showed no significant changes in high-density lipoprotein and TGL/TAG. The dose–response model showed that a 3-g/d dose of oat or barley β-glucan was sufficient to decrease TC.

Conclusion

Consumption of 3 g/d of oat or barley β-glucan is sufficient to decrease blood cholesterol, whereas the effect on BGL is still inconclusive, with high heterogeneity, and requires further clinical research studies with longer intervention periods.

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

References (43)

  • A. Cavallero et al.

    High (1→3, 1→4)-β-glucan barley fractions in bread making and their effects on human glycemic response

    J Cereal Sci

    (2002)
  • N. Tapola et al.

    Glycemic responses of oat bran products in type 2 diabetic patients

    Nutr Metab Cardiovasc Dis

    (2005)
  • E. Östman et al.

    Glucose and insulin responses in healthy men to barley bread with different levels of (1→3; 1→4)-β-glucans; predictions using fluidity measurements of in vitro enzyme digests

    J Cereal Sci

    (2006)
  • A.C. Nilsson et al.

    Including indigestible carbohydrates in the evening meal of healthy subjects improves glucose tolerance, lowers inflammatory markers, and increases satiety after a subsequent standardized breakfast

    J Nutr

    (2008)
  • M.E. Pick et al.

    Oat bran concentrate bread products improve long term control of diabetes: a pilot study

    J Am Diet Assoc

    (1996)
  • I.A. Castro et al.

    Effect of eicosapentaenoic/docsahexaenoic fatty acids and soluble fibers on blood lipids of individuals classified into different levels of lipidemia

    Nutrition

    (2007)
  • U. Tiwari et al.

    Factors influencing β-glucan levels and molecular weight in cereal-based products

    Cereal Chem

    (2009)
  • Final rule for food labeling: health claims. Oats and coronary heart disease

    Fed Reg

    (1997)
  • Health claims: soluble fibre from certain foods and coronary heart disease (CHD)

    Fed. Reg

    (2005)
  • M. Biörklund et al.

    Changes in serum lipids and postprandial glucose and insulin concentrations after consumption of beverages with β-glucans from oats or barley: a randomised dose-controlled trial

    Eur J Clin Nutr

    (2005)
  • M.C. Casiraghi et al.

    Post-prandial responses to cereal products enriched with barley β-glucan

    J Am Coll Nutr

    (2006)
  • Cited by (0)

    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.

    View full text