A systematic review and meta-analysis of randomized controlled trials of the effect of barley ß-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 (ß-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 ß-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 ß-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 I2 statistic. RESULTS: Fourteen trials (N=615) were included in the final analysis. A median dose of 6.5 and 6.9 g/day of barley ß-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 ß-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.