High Fiber Diet Does Not Prevent Colon Cancer

This article stresses the fact that diet and other measures are not a reliable way to prevent colon cancer. The only way that works is the systematic search and removal of any colon polyps before there are any symptoms and even before any actual cancer cells develop. Colonoscopy is one of our main tools of colon cancer prevention.

AP Press
January 21, 1999

A large new study has found no evidence that eating lots of high-fiber foods like bran, beans and whole wheat bread helps lower the risk of colon cancer, a surprising conclusion that contradicts years of dietary advice.

The study, published in today's New England Journal of Medicine, tracked the colon and rectal health of 88,757 women who participated in the Harvard-based Nurses Health Study over 16 years. It is one of the biggest cancer studies of its kind ever.

From 1980 to 1996, 787 of the women developed cancer of the colon or the rectum. The risk was the same, regardless of how much fiber they ate. The researchers said they believe the findings apply to men as well.

Dr. Charles S. Fuchs and his colleagues at the Dana-Farber Cancer Institute, Brigham and Women's Hospital and Harvard Medical School said they were astounded to find that women who ate low-fiber foods were no more likely to develop colon cancer than those who stuck to bran muffins and broccoli.

"As a practicing physician and as a researcher, this is a hypothesis that has stood the test of time,'' Fuchs said. "There has been such an abundant enthusiasm for this hypothesis, so the important message here is that fiber, overall, has no protective effect.''

However, previous studies have found that a diet rich in fruits, vegetables and whole grains has other health benefits, including reducing the risk of heart disease, high blood pressure and certain types of diabetes.

And Fuchs said the benefits of fiber in protecting against other problems like high blood pressure and heart disease — the No. 1 killer in the country — are undeniable.

"If people are taking fiber for any of those reasons, then keep doing it. If the primary concern is to prevent colon cancer, then I wouldn't try fiber. I'm not sure that's going to work,'' he said.

The study participants were healthy women, 34 to 59, who had no history of cancer. They filled out dietary questionnaires in 1980, 1984 and 1986, and researchers followed up with the women until mid-1996.

Dr. Michael Thun, who heads epidemiological research for the American Cancer Society, said he was surprised by the findings but doubts his organization will change its nutritional guidelines because people who eat more fruits and vegetables generally suffer fewer cases of cancer of the mouth, throat, larynx, esophagus, stomach, and lungs.

"People should base their behavior on all of the evidence rather than on one study,'' Thun said. "One shouldn't either zigzag erratically with each new study or lapse into cynicism. The fact is that the main components of a healthy lifestyle have been clear and steady for some years.''

He stressed that there may be other properties of vegetables, including the vitamin folate, that could lower the risk of cancer and that people who eat more fruits, vegetables and whole grains also tend to be less obese and suffer fewer health problems.

In an accompanying editorial, Dr. John Potter of the Fred Hutchinson Cancer Research Center in Seattle wondered whether questionnaires about a person's past eating habits can be accurate and if nurses, who are generally more health-conscious than other people, are a representative sample.

Potter said there is evidence to suggest that high sugar and calorie consumption and a lack of exercise may be to blame for colon cancer, but more research is necessary. "We have barely begun,'' he said.

Text & Images Courtesy of Three Rivers Endoscopy Center
© Dr. Robert Fusco, Three Rivers Endoscopy Center, All Rights Reserved

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