A systematic review and meta-analysis of randomized controlled trials of the effect of barley β-glucan on LDL-C, non-HDL-C and apoB for cardiovascular disease risk reductioni-iv

Background/Objectives:: There has been recent interest in barley as a therapeutic food owing to its high content of beta-glucan (β-glucan), a viscous soluble fiber recognized for its cholesterol-lowering properties. The objective of this study was to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) investigating the cholesterol-lowering potential of barley β-glucan on low-density lipoprotein cholesterol (LDL-C), non-high-density lipoprotein cholesterol (non-HDL-C) and apolipoprotein B (apoB) for cardiovascular disease (CVD) risk reduction. Methods:: MEDLINE, Embase, CINAHL and the Cochrane CENTRAL were searched. We included RCTs of ⩾3-week duration assessing the effect of diets enriched with barley β-glucan compared with controlled diets on LDL-C, non-HDL-C or apoB. Two independent reviewers extracted relevant data and assessed study quality and risk of bias. Data were pooled using the generic inverse-variance method with random effects models and expressed as mean differences (MDs) with 95% confidence intervals (CIs). Heterogeneity was assessed by the Cochran Q-statistic and quantified by the I²statistic. Results:: Fourteen trials (N=615) were included in the final analysis. A median dose of 6.5 and 6.9 g/day of barley β-glucan for a median duration of 4 weeks significantly reduced LDL-C (MD=−0.25 mmol/l (95% CI: −0.30, −0.20)) and non-HDL-C (MD=−0.31 mmol/l (95% CI: −0.39, −0.23)), respectively, with no significant changes to apoB levels, compared with control diets. There was evidence of considerable unexplained heterogeneity in the analysis of non-HDL-C (I²=98%). Conclusions:: Pooled analyses show that barley β-glucan has a lowering effect on LDL-C and non-HDL-C. Inclusion of barley-containing foods may be a strategy for achieving targets in CVD risk reduction.