Effect of dietary fiber intake on blood pressure: A meta-analysis of randomized, controlled clinical trials

Objective: We conducted a meta-analysis of 25 randomized controlled trials published in English-language journals before February 2004, to assess the effect of dietary fiber intake on blood pressure (BP). Design: Using a standardized protocol, information on study design, sample size, participant characteristics, duration of follow-up and change in mean BP, was abstracted. The data from each study were pooled using a random effects model to provide an overall estimate of dietary fiber intake on BP. Intervention: Dietary fiber intake was the only significant intervention difference between the active and control groups. Results: Overall, dietary fiber intake was associated with a significant -1.65 mmHg [95% confidence interval (CI), -2.70 to -0.61] reduction in diastolic BP (DBP) and a non-significant -1.15 mmHg (95% CI, -2.68 to 0.39) reduction in systolic BP (SBP). A significant reduction in both SBP and DBP was observed in trials conducted among patients with hypertension (SBP -5.95 mmHg, 95% CI, -9.50 to -2.40; DBP -4.20 mmHg, 95% CI, -6.55 to -1.85) and in trials with a duration of intervention ≥8 weeks (SBP -3.12 mmHg, 95% CI, -5.68 to -0.56; DBP -2.57 mmHg, 95% CI, -4.01 to -1.14). Conclusions: Our results indicate that increased intake of dietary fiber may reduce BP in patients with hypertension and suggests a smaller, non-conclusive, reduction in normotensives. An intervention period of at least 8 weeks may be necessary to achieve the maximum reduction in BP. Our findings warrant conduct of additional clinical trials with a larger sample size and longer period of intervention to examine the effect of dietary fiber intake on BP.