Colon cancer risk not lower with high-fibre diet: review

Last Updated Tue, 13 Dec 2005 16:01:51 EST

CBC News - Eating a diet high in fibre does not reduce the risk of colorectal cancer, but it is a good idea for your heart and for preventing diabetes, the authors of a new review say.

The idea that fibre may protect against colon cancer is based on the idea that the foods help keep us regular. By bulking up stool, it was thought that insoluble fibre like wheat bran helps waste move through faster, diluting carcinogens in the bowel.

But proof that dietary fibre from fruits and vegetables, cereals or bran reduces the risk of colon cancer has been elusive, with animal studies, population studies and randomized clinical trials showing inconsistent results.

The latest study, published in the Dec. 14 issue of the Journal of the American Medical Association, adds to the disappointment.

Yikyung Park of the Harvard School of Public Health in Boston and colleagues analyzed data from 13 international trials involving more than 725,000 men and women who were followed for six to 20 years.

During the follow-up, 8,081 colorectal cancer cases were identified.

A diet high in fibre did not reduce the risk of colon cancer, after adjusting for age and other factors such as family history, smoking and red meat intake, Park's team concluded.

"Although high dietary fibre intake may not have a major effect on the risk of colorectal cancer, a diet high in dietary fibre from whole plant foods can be advised because this has been related to lower risks of other chronic conditions such as heart disease and diabetes," the researchers wrote.

Heather Logan, director for cancer control policy at the Canadian Cancer Society, agreed, saying it's "still important and sound advice" for people to incorporate fruits and vegetables in their diet.

Barry Stein, president of the Colorectal Cancer Association of Canada, changed his diet substantially when he was diagnosed with colon cancer10 years ago.

Stein said he will stick with the diet changes. For him, the most important step toward decreasing the risk of colon cancer is screening.

"There is nothing like screening that is going to reduce the number of deaths from colorectal cancer," said Stein. "We need that immediately implemented across the country."

As for whether fibre helps prevent other types of cancer, the largest randomized study of diet and breast cancer is underway. Results should be released early next year.


http://www.cbc.ca/story/science/nat...olon051213.html

I have always wondered if it was because people were eating more fiber OR if it was simply because people were eating lower glycemic ???

We know that eating a lot of high glycemic foods causes cancer. So eating more fiber means eating less cancer causing foods.

How funny, the fiber myth takes another hit...

I have yet to find any research that shows that fiber lowers the risk of heart disease or diabetes.

"Well, it doesn't have any benefit that we can show but we know it's good anyway, and that's what we believe, so there."

When I took a class on cancer they said cancer is caused by 2 occurences that break both strands of DNA leading to mutated cells. Many cancers they've found the gene that causes one to be born with one or both strands broken. The other strand is broken by environmental factors. It never made any sense as one who has seen 3 generations of my family die from high rates of colon cancer that fiber or fat in the diet would make a difference in so many people with so many different eating patterns. 10 years ago we were told we Scots have colon cancer because of all the fat in the dairy we eat.

Maybe I have a huge bias being a DNA chemist but I think we're genetically programmed to get diseases and die. I think people fixate on diet because its one of very few things we can control.

I wonder what those nutrition experts are going to do now. All their sacred truths (which seem to be funded by the agro sector) are falling down, one study at a time.

Eating fiber just = eating less carbs. Fiber is non-food which prevents & slows the absorption of true foods, including sugar. It's like dieting (under eating) without consciously trying.

To get many of the benefits of high fiber and then some, simply reduce starches in diet.

The way I understand it, some studies showed that increased fruit/veggies/whole grains in the diet corelated with decreased colon cancer, but they assumed it was the fiber. This was never proven. In fact, I recall reading of a study (I can't find it now for the life of me) in which they compared fruit and vegetable intake to an equivalent amount of fiber in the form of a supplement, and the fiber supplement group had such terrible results that they had to suspend the study.

Boy, I had the fibre myth drummed into me by a mother who suffered colon polyps and saw her father die of colon cancer. So I'm programmed for it - and getting 5-yearly screenings (NO fun at all!!!). So far so good. Well, I've always had a high vege and fruit intake, so maybe that has given some protection. Or maybe I'm just doooooomed...