Fiber may help protect against colon cancer.(Two Large Studies)

Roughage just might prevent colon cancer after all.

Contradicting previous evidence, two large multicenter studies--one American, the other European--have documented a strong association between increased consumption of dietary fiber and a reduced risk of colon cancer.

"The new results give fresh impetus to fundamental research to determine the reasons for the protective action of dietary fiber or to establish the definitive clinical trial," Dr. Lynnette R. Ferguson and Dr. Philip J. Harris of the University of Auckland (New Zealand) said in an editorial accompanying the two studies (Lancet 361[9368]:1487-88, 2003).

The larger of the two studies, the European Prospective Investigation Into Cancer and Nutrition (EPIC), involved more than half a million (519,978) subjects in 10 countries. After answering extensive dietary questionnaires, the participants were followed for an average of 4.5 years. During that time, they developed a total of 1,065 incident colorectal cancers, including 706 in the colon and 359 in the rectum.

The risk for colorectal cancer was 25% lower among subjects with the highest quintile of fiber intake (31.9 g/day for women, 35.6 g/day for men) than among those in the lowest quintile (12.6 g/day for women, 12.8 g/day for men). The risk dropped by about 8% for each quintile increase in fiber, said Dr. Sheila A. Bingham of the MRC Dunn Human Nutrition Unit, Cambridge, England, and her associates (Lancet 361[9368]:1496-1501, 2003).

Fiber was equally protective for colon and rectal cancer combined in men and women, but this finding was not significant for rectal cancer when considered separately. Adjustment for red meat consumption did not change the results.

When the total fiber intake from the dietary questionnaires was calibrated with a 24-hour recall ...