Aims: Dietary fiber intake, especially viscous soluble fiber, has been established as a means to reduce cardiometabolic riskfactors. Whether this is true for blood pressure remains controversial. A systematic review and meta-analysis of randomized controlled trials (RCT) was conducted to investigate the effects of viscous soluble fiber supplementation on blood pressure and quantify the effect of individual fiber.
Data synthesis: MEDLINE, Embase, and Cochrane databases were searched. We included RCT of ≥4-weeks in duration assessing viscous fiber supplementation from five types: β-glucan from oats and barley, guar gum, konjac, pectin and psyllium, on systolic blood pressure (SBP) and diastolic blood pressure (DBP). Study data were pooled using the generic inverse variance method with randomeffects models and expressed as mean differences (MD) with 95% confidence intervals (CIs). Twenty-two (N = 1430) and twenty-one RCT (N = 1343) were included in the final analysis for SBP and DBP, respectively. Viscous fiberreduced SBP (MD = -1.59 mmHg [95% CI: -2.72,-0.46]) and DBP (MD = -0.39 mmHg [95% CI: -0.76,-0.01]) at a median dose of 8.7 g/day (1.45-30 g/day) over a median follow-up of 7-weeks. Substantial heterogeneity in SBP (I2 = 72%, P < 0.01) and DBP (I2 = 67%, P < 0.01) analysis occurred. Within the five fiber types, SBP reductions were observed only for supplementation using psylliumfiber (MD = -2.39 mmHg [95% CI: -4.62,-0.17]).
Conclusion: Viscous soluble fiber has an overall lowering effect on SBP and DBP. Inclusion of viscous fiber to habitual diet may have additional value in reducing CVDrisk via improvement in blood pressure.