Background Dietary fiber is part of a healthy diet and may exert a protective effect in the cardiovascular system. The effect of fiber intake on blood pressure (BP) has not yet been established.

__Methods __ We performed a meta-analysis of randomized placebo-controlled trials to estimate the effect of fiber supplementation on BP overall and in population subgroups. Original articles published between January 1, 1966, and January 1, 2003, were retrieved for 24 trials that fulfilled criteria for meta-analysis. Data were abstracted on fiber dose, fiber type, BP changes, study design features, and study population characteristics. A random-effects model was used for meta-analysis.

Results Fiber supplementation (average dose, 11.5 g/d) changed systolic BP by –1.13 mm Hg (95% confidence interval: –2.49 to 0.23) and diastolic BP by –1.26 mm Hg (–2.04 to –0.48). Reductions in BP tended to be larger in older (>40 years) and in hypertensive populations than in younger and in normotensive ones.

Conclusion Increasing the intake of fiber in Western populations, where intake is far below recommended levels, may contribute to the prevention of hypertension.