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Meta-analysis finds fiber cereals, grains cut colon cancer risk

Kathleen Blanchard's picture
Fiber cereals and whole grains cut colorectal cancer risk according to BMJ study

Eating a high fiber diet can help protect against heart disease, but whether whole grains and dietary fiber can fight colon cancer has remained unclear - mostly because researchers haven't had enough long-term evidence.

Results of a new meta-analysis show a direct association between eating cereals with fiber and whole grains and lower risk of colon cancer.

The current study, which included an analysis of 25 prospective studies with almost two million participants, failed to find benefit for lowering chances of the disease from eating high fiber fruits and vegetables and legumes.

But for those who ate three servings of dietary fiber from whole grains daily, the risk of colorectal cancer dropped 17 percent.

Increasing fiber in the diet by 10-grams a day was associated with a 10 percent reduction in colon cancer, but the benefits for rectal cancer from fiber were not as strong.

The finding comes from Teresa Norat, PhD, of Imperial College London, and colleagues, who reported the findings online in BMJ.

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"Our results provide further support for public health recommendations to increase the intake of dietary fiber in the prevention of colorectal cancer. However, they suggest a particular benefit of increasing cereal fiber and whole grain intake," write the authors.

The researchers aren’t sure exactly how fiber lowers the risk of colon cancer or which types of whole grain are best. Past studies have suggested whole grain rye may be better than other types of grains for keeping cells in the intestines healthy.

"But factors such as increased satiety, stabilized glucose homoeostasis and insulin response, and the fermentation of fiber and resistant starch in the colon to produce short chain fatty acids are probably important”, according to Anne Tjonneland, PhD, and Anja Olsen, PhD, of the Danish Cancer Society.

Colon cancer is preventable, but symptoms may not be present until the disease is advanced. Early screening with colonoscopy, fecal occult blood testing (FOBT), and sigmoidoscopy are recommended for adults over age 50.

Exercise, limiting red meat, exercise, maintaining a healthy weight and increasing fiber in the diet – to include cereals and whole grains – are all interventions that can reduce the chances of developing colon cancer.

The newest meta-analysis suggests 3 servings of fiber from whole grains, versus fruits, vegetables and legumes, can lower the chances of colorectal cancer by 17 percent. Each 10 gram increase in daily fiber cuts the chances of the disease by 10 percent.

Aune D, et al
"Dietary fibre, whole grains, and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies"
BMJ 2011; DOI: 10.1136/bmj.d6617.

Image credit: Morguefile