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).
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.
Dietary fiber intake was the only significant intervention difference between the active and control groups.
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).
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.
aDepartment of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana
bDepartment of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA
Received 10 May, 2004
Revised 13 October, 2004
Accepted 14 October, 2004
Sponsorship: This study was supported by grants (HL60300 and HL68057) from the National Heart, Lung, and Blood Institute of the National Institutes of Health and partially by the Tulane-Charity-LSU General Clinical Research Center (RR05096). The sponsors of the study had no role in its study design, in the collection, analysis, or interpretation of data, or in writing the report. The authors do not have any personal connection with companies producing food products.
Correspondence and requests for reprints to Jiang He, Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, 1440 Canal Street, Ste 20, SL-18, New Orleans, Louisiana 70112, USA. Tel: +1 504 988 5165; fax: +1 504 988 1568; e-mail: firstname.lastname@example.org