Focus: Colorectal Cancer and Fiber
For many years, the common wisdom was that a diet rich in
fiber could help prevent colon cancer. You may still even see words to that
effect on some cereal boxes or on Web sites of cereal companies.
But several studies in past years have not shown any real
link to high fiber intake and lower incidence of
colon cancer. Most recently,
researchers from the Harvard School of Public Health looked at 13 earlier
studies that included at a total of 725,000 women and men. Timeframes of the
studies ranged from six to 20 years. The Harvard report did not find conclusive
evidence that getting plenty of fiber is the key to preventing colon cancer.
On the other hand, a large European study recently
indicated that there was a statistical link between high-fiber diets and
a decreased risk of colorectal cancer.
The notion that fiber is protective against colon cancer
began in 1969, when researchers came to the conclusion that people who lived in
rural Africa had a lower rate of colorectal cancer than people in industrialized
countries. The researchers theorized that this was because the Africans’ diets
were high in vegetables and low in meat. It made sense too, because fiber, which
is the indigestible part of plant products, helps to speed the passage of waste
products in the colon.
Plenty of reasons to have a high-fiber diet
None of this means that you shouldn’t include high-fiber
foods in your diet. Fiber helps fight against heart disease and diabetes, and it
also helps you to manage certain digestive disorders. High fiber foods can also
help prevent obesity, because they make you feel more full and satisfied.
There are two kinds of fiber—soluble, which dissolves in
water, and insoluble, which does not. Soluble fibers include oatmeal; oat bran;
nuts; seeds; dried peas, beans and lentils; apples; pears; strawberries;
blueberries. Insoluble fiber includes whole grains (such as whole wheat breads,
barley and brown rice); whole grain breakfast cereals; carrots; cucumbers;
carrots; tomatoes; zucchini.
Everybody should include plenty of both types of fiber in
their daily food intake.
Colon cancer screening best way to lower risk
Until the fiber issue is cleared up, most experts will tell
you that the best way available to prevent colon cancer is to get screened for
the condition. Colonoscopies enable doctors to remove precancerous polyps and
small tumors in the colon before the threat of cancer becomes serious.
Guidelines recommend that everyone begin colonoscopy screening by age 50. But
you should talk with your doctor about your family history and risk of colon
cancer to determine whether you should begin screening earlier.
Harvard School of
Public Health;Journal of the American Medical Association, 14 December