Thursday, December 01, 2011

Meta-analysis supports lower colorectal cancer risk with high fiber intake



November 26, 2011

ST LOUIS (MD Consult) - A high intake of dietary fiber—especially cereals and whole grains—is associated with a lower risk of colorectal cancer, according to a study published in the November 26, 2011, issue of the British Medical Journal.

A systematic review was performed to identify cohort and case-control studies of the relationship between fiber and whole-grain intake and the incidence of colorectal cancer. Data from 25 prospective studies were pooled for meta-analysis. The lead author was Dagfinn Aune of Imperial College London.

Based on data from 16 studies, the summed relative risk of colorectal cancer at a total daily fiber intake of 10 g was 0.90. There was no significant reduction in colorectal cancer risk at the same daily intake of fruit or vegetable fiber, based on 9 studies each; or legume fiber, based on 4 studies.

However, higher intake of cereal fiber was associated with a significant reduction in colorectal cancer: summary relative risk 0.90, based on 8 studies. For an increase of 3 servings per day of whole grain, the summary relative risk of colorectal cancer was 0.83, based on 6 studies.

It has been suggested that increased intake of dietary fiber may reduce the risk of colorectal cancer, although studies of this issue have reached conflicting results. With the addition of recent studies, the available evidence base is large enough to clarify this association, including the dose-response relationship.

The results show a significant reduction in colorectal cancer incidence for individuals with a high intake of dietary fiber. The protective effect appears particularly strong for intake of cereal fiber and whole grains. The investigators conclude, "Our results indicate a 10% reduction in risk of colorectal cancer for each 10 g/day intake of total dietary fibre and cereal fibre and about a 20% reduction for each three servings (90 g/day) of whole grain daily, and further reductions with higher intake."

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