Link between low fiber and colon cancer -- in dispute

[tracer]

In Cecil’s 1991 article on dietary fiber at http://www.straightdope.com/classics/a3_094.html, the Master states that:

the link between low fiber and colon cancer is firmly established.

Well, not any more! Two large studies in the New England Journal of Medicine back in the year 2000 failed to find any link between the consumption of dietary fiber (cereal or vegetable) and the incidence of colorectal cancer.

Here’s an archived CNN article about it:
http://www.cnn.com/2000/HEALTH/cancer/04/19/colon.cancer/

[KarlGauss]

And, along similar lines, some recent studies from the Journal of the American Medical Association (JAMA) showing that:

• a low fat diet (with lots of fibre) doesn’t reduce the development of colon cancer

• a low fat diet (with lots of fibre) doesn’t reduce the development of invasive breast cancer

• a low fat diet (with lots of fibre) doesn’t reduce the development of cardiovascular disease

[tracer]

@KarlGauss

• a low fat diet (with lots of fibre) doesn’t reduce the development of colon cancer

Hmmm … according to that article, not only did the diet-modification group reduce its fat intake and increase its fiber intake, it also increased its fruit and vegetable intake. So it would seem that neither a low fat, nor a high fiber, nor fruit-and-veggie-rich diet, makes much of a difference in reducing ones risk of colon cancer.

[foolsguinea]

@tracer

Hmmm … according to that article, not only did the diet-modification group reduce its fat intake and increase its fiber intake, it also increased its fruit and vegetable intake. So it would seem that neither a low fat, nor a high fiber, nor fruit-and-veggie-rich diet, makes much of a difference in reducing ones risk of colon cancer.

Or… the beneficial effect of one change was neutralised by another.

[elelle]

From Tracer’s original JAMA link:

As part of that study, 719 people ate half an ounce of wheat bran fiber each day and another 584 ate less than a tenth of an ounce.

Colonoscopies conducted after three years showed the risk of developing a polyp was the virtually the same in both groups.

But the study authors expressed concern that three years may have not been enough time to see a difference in the two groups. However, there have also been two other studies which did not find cereal fiber to reduce risk of colon cancer. These were the Nurses’ Health Study and the Health Professionals’ Follow-up study.

Researchers had been hopeful there was a connection between high-fiber diets and a reduction in the risk of colon cancer. Studies outside the U.S. had found colorectal cancer rates to be lower in places where people consumed more fruits and vegetables, and higher in people from those areas who changed to diets higher in fat and lower in fiber.

Byers, in his editorial, said, the new research shows, “we still do not understand why.”

But experts say people shouldn’t give up on high-fiber, low-fat diets just yet. This type of diet is still recommended for overall health and disease prevention.

“All it (the NCI study) says is that at one stage over a four year period of time the diet had no effect. Now cancer, particularly colon cancer, may take 15 years to develop. We don’t know the effect of diet on the other stages of the cancer,” said Dr. Moshe Shike of Memorial Sloan-Kettering Cancer Center.

A high-fiber diet can reduce the risk of heart disease, high blood pressure, and diabetes.

The American Institute of Cancer Research (AICR) reacted to the NCI study saying these newest findings, “should not prompt people to abandon diets that have been consistently linked to reducing the risk of colon cancer.”

Half an ounce of wheat bran fiber daily later in life does not compare at all to a diet based on whole grains, vegetables, and fruit as a lifelong diet. I see no information on the age of the participants , nor the fact that they significantly changed their diet except for the addition of a wee bit of fiber. These stand out as significant points, to my mind.

No, wait, the age factor is in that article:

Because the average age of NCI study participants was 61, AICR spokeswoman Ritva Butrum said the findings may simply show dietary changes need to be made early in life.

Karl Gauss’ links are to an 8 year study done on women “50-79”. I’m glad those studies are done, but don’t know if one can extrapolate the results to having had a lifelong diet of whole grains, etc.

I am not a Doctor, and much respect the above posters, but I do think a 15 or so year study on people in their 30-50’s might be more indicative of dietary health.

[picunurse]

@KarlGauss

And, along similar lines, some recent studies from the Journal of the American Medical Association (JAMA) showing that:

• a low fat diet (with lots of fibre) doesn’t reduce the development of colon cancer

• a low fat diet (with lots of fibre) doesn’t reduce the development of invasive breast cancer

• a low fat diet (with lots of fibre) doesn’t reduce the development of cardiovascular disease

Then why am I still being forced to eat tree bark for breakfast?
Now, if someone will only clear the Egg’s name, I can have my Egg’s Benedict again.