The effects of dietary fibre on C-reactive protein, an inflammation marker predicting cardiovascular disease.

BACKGROUND: C-reactive protein (CRP), a sensitive marker of inflammation, is an independent predictor of future cardiovascular disease (CVD), which is a major cause of death worldwide. In epidemiological trials, high-fibre intakes have consistently been associated with reduction in CVD risk and CRP levels.
OBJECTIVE: The objective of this study was to assess the influence of dietary fibre (DF) on CRP in clinical trials. DATA SOURCES: Databases were searched from the earliest record to April 2008 and supplemented by crosschecking reference lists of relevant publications. STUDY SELECTION: Human adult intervention trials, at least 2 weeks in duration, with an increased and measurable consumption of DF were included and rated for quality. DATA SYNTHESIS: Seven clinical trials were included, and six of these reported significantly lower CRP concentrations of 25-54% with increased DF consumption with dosages ranging between 3.3-7.8 g/MJ. The seventh trial with psyllium fibre supplementation failed to lower CRP levels significantly in overweight/obese individuals. Weight loss and altered fatty acid intakes were present in most of the studies.
CONCLUSIONS: In the presence of weight loss and modified saturated, monounsaturated and polyunsaturated fat intakes, significantly lower CRP concentrations (downward arrow 25-54%) are seen with increased fibre consumption (> or =3.3 g/MJ). Mechanisms are inconclusive but may involve the effect of DF on weight loss, and/or changes in the secretion, turnover or metabolism of insulin, glucose, adiponectin, interleukin-6, free fatty acids and triglycerides. Clinical studies of high- and low-fibre diets are needed to explore the potential favourable effects as observed epidemiologically, and to understand individual susceptibility to its anti-inflammatory effect and long-term cardiovascular reduction.