Effects of dietary fibre type on blood pressure: A systematic review and meta-analysis of randomised controlled trials of healthy individuals

Objective: To determine the effect of different types of dietary fibre on systolic and diastolic blood pressure. Methods: A systematic review of the literature and a meta-analysis of randomised controlled trials using random effects models. Eligibility criteria for studies included randomised controlled trials of at least 6 weeks duration testing a fibre isolate or fibre rich diet against a control or placebo published between 1st January 1990 and 1st December 2013. Results: 28 trials met the inclusion criteria and reported fibre intake and systolic blood pressure (SBP) and/or diastolic blood pressure (DBP). 18 trials were included in a meta-analysis. Studies were categorised into one of twelve fibre-type categories. The pooled estimate for all fibre types were -0.9 mmHg (95% CI -2.5 to 0.6 mmHg), and -0.7 mmHg (95% CI -1.9 to 0.5 mmHg) for SBP and DBP respectively. Analyses of specific fibre types concluded that diets rich in beta-glucans reduce SBP by 2.9 mmHg (95% CI 0.9 to 4.9 mmHg) and DBP by 1.5 mmHg (95% CI 0.2 to 2.7 mmHg) for a median fibre difference of 13 g. Heterogeneity for individual fibre types was generally low. Conclusions: Higher consumption of beta-glucan fibre found in oats and barley is associated with lower systolic and diastolic blood pressure; however evidence for other types of fibre was not consistent. In many countries total dietary fibre consumption is considerably lower than recommended. Policies which increase oat and barley consumption and reduce cardiovascular disease, through lowering blood pressure, should be encouraged.