High-Fiber Diet May Not Reduce Colon Cancer Risk 35648

High-Fiber Diet May Not Reduce Colon Cancer Risk

ATLANTA--In the April 20 edition of The New England Journal of Medicine, twolarge studies found that a high-fiber diet may not protect against colon cancer.Previously, studies had suggested that a diet high in fiber could reduce a person's risk,but research had not directly measured the anti-cancer effects of a high-fiber diet.

"There may be reasons to eat a diet that is low in fat and high in fiber, fruitsand vegetables or to supplement the diet with a food high in cereal fiber," said TimByers of the University of Colorado School of Medicine. "Preventing colorectaladenomas, at least for the first three to four years, is not one of them."

Colorectal adenomas--polyps that can turn into tumors--gauge the effectiveness of ahigh-fiber diet because they appear faster, while colorectal cancer itself can take yearsto develop.

In the first study, conducted at the National Cancer Institute (NCI), 958 people wereput on low-fat, high-fiber, high-fruit and vegetable diets. Another 947 people were giveninformation on eating healthy and were told to follow their usual diets. All participantshad at least one pre-cancerous polyp removed in the six months prior to the study. Afterfour years, researchers found that both groups had the same chances of developing anotherpolyp.

In the second study, conducted at the Arizona Cancer Center, 719 people ate half anounce of wheat bran fiber each day, while another 584 ate less than a tenth of an ounce.After three years, colonoscopies found that the risk of developing a polyp was the samefor both groups.

Some researchers believe three and four years was not a long enough time to observe thegroups. "All the NCI study says is that at one stage over a four year period of time,the diet had no effect," said Dr. Moshe Shike of Memorial Sloan-Kettering CancerCenter. "Cancer, particularly colon cancer, may take 15 years to develop." Also,because the average age of the NCI study participants was 61, these findings may show thatdietary changes need to be made earlier in life.

A high-fiber diet can still reduce the risk of heart disease, high blood pressure anddiabetes. For further information, visit www.nejm.org/context/2000/0342/0016/1149.asp.