Dietary fiber doesn't lower colorectal cancer risk

Although the potential connection between dietary fiber and colorectal cancer has long held an attraction for both medical researchers and the general public, investigators report that the results of a large new study do not support this link.

"Our study did not show any association between how much dietary fiber you eat and your risk of colorectal cancer," lead author Dr. Arthur Schatzkin told Reuters Health. However, "we did find... that consumption of whole grain foods confers a lower risk of developing this disease."

Schatzkin of the National Institutes of Health, Bethesda, Maryland and colleagues came to this conclusion after analyzing survey responses from more than 291,000 men and 197,000 women between 50 and 71 years old.
The researchers report their findings in the American Journal of Clinical Nutrition.

The range of daily dietary fiber for the whole group was 6.6 grams per kilocalories for the lowest amount to 15.9 grams per kilocalories for the highest amount. The corresponding range for men was 6.4 to 15.2, and for women, 7.0 to 16.8.

After analyzing fiber from different food sources, the team found that only fiber from grains was associated with a lower risk of colorectal cancer. The risk of colorectal cancer was lowered by 14 percent among the subjects with the highest amounts of grain in their diet compared with those with the lowest amounts. The association with whole grains was stronger for rectal than for colon cancer.

Nevertheless, concluded Schatzkin, the study findings support the recommendation of eating more unprocessed cereals or pulses and avoiding refined starchy foods to lower the risk of colorectal cancer.

SOURCE: American Journal of Clinical Nutrition, May 2007