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Evidence summaries

Dietary Fiber and Hypertension

Dietary fiber may slightly decrease blood pressure. Level of evidence: "C"

A systematic review 1 included 24 studies with a total of 1 404 subjects. The meta-analysis showed a statistically non-significant effect of fibre supplementation (average dose 11.5 g/day) on systolic BP of -1.13 mmHg (95% CI -2.49 to 0.23) and a statistically significant effect on diastolic BP of -1.26 mmHg (95% CI -2.04 to -0.48).

Another systematic review and meta-analysis 2 included 22 studies with a total of 1 430 subjects assessing the effect of viscous fiber supplementation (β-glucan from oats and barley, guar gum, konjac, pectin and psyllium) on BP. Viscous fiber reduced systolic BP (MD -1.59 mmHg, 95% CI -2.72 to -0.46) and diastolic BP (MD -0.39 mmHg, 95% CI -0.76 to -0.01) at a median dose of 8.7 g/day over a median follow-up of 7-weeks. Substantial heterogeneity in SBP (I2 = 72%) and DBP (I2 = 67%) analysis occurred. Within the five fiber types, SBP reductions were observed only for supplementation using psyllium fiber (MD -2.39 mmHg, 95% CI -4.62 to -0.17).

Comment: The quality of evidence is downgraded by sparse data and possibility of publication bias (The funnel plot showed that there was a possibility that more small trials showing large reductions in BP were included).

References

  • Streppel MT, Arends LR, van 't Veer P, Grobbee DE, Geleijnse JM. Dietary fiber and blood pressure: a meta-analysis of randomized placebo-controlled trials. Arch Intern Med 2005 Jan 24;165(2):150-6. [PubMed]
  • Khan K, Jovanovski E, Ho HVT et al. The effect of viscous soluble fiber on blood pressure: A systematic review and meta-analysis of randomized controlled trials. Nutr Metab Cardiovasc Dis 2018;28(1):3-13. [PubMed]

Primary/Secondary Keywords