Fibre intake and blood pressure: More facts, more questions

The meta-analysis on the effects of increased dietary fibre on blood pressure (BP), published in this issue of the JH, (1) calls for renovated attention on one of the many aspects of our dietary habits deemed to be relevant for cardiovascular prevention. Although Evans' work is not the first comprehensive assessment of the possible relationship between increased fibre intake and BP, the ten years elapsed from the two previous systematic reviews (2-3) on the same subject have seen the publication of several new reports which allowed Evans et al to carry a more in-depth evaluation and, in particular, to try and dissect out the effects of different types of fibre in addition to their overall impact on BP. One merit of the review is that it is exclusively based on the analysis of randomized controlled trials, most of which rated as good or very good quality, whereas previous evidence suggesting that larger habitual consumption of dietary fibre is beneficial for human health, by reducing the risk of obesity, type 2 diabetes, hypertension and their cardiovascular complications, has mainly come from observational studies (4-8). The most novel content of Evans' work is the evidence in favor of a particularly beneficial effect on BP of beta-glucans, a variety of soluble dietary fibre abundant in oats- and barley-rich foods, whereas the authors found little or no statistical evidence of the BP impact of other types of dietary fibre.