- Contradicting years of dietary wisdom,
a large new study found no evidence that eating lots of high-fiber foods
like bran, beans and whole wheat bread does anything to lower the risk
of colon cancer.
-
- But don't put down that apple yet: 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.
-
- The study, published in Thursday'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 undertaken.
-
- 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, he 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
D. 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.
|
