Nov. 10, 2011 -- Eating a high-fiber diet is linked with a reduced risk of colorectal cancer, according to new research that analyzed 25 different studies.
Total fiber intake, as well as fiber from whole grains and from cereals, was most strongly linked with a reduction in colorectal cancer risk, the researchers say.
The evidence was weaker for fiber from fruits, vegetables, and legumes, says study researcher Dagfinn Aune, a research associate at Imperial College London.
"It doesn't mean you shouldn't eat your fruits and vegetables," he tells WebMD. He found fewer studies on the impact on colon cancer risk of fiber from fruits, vegetables, and legumes than studies looking at the other foods, he says. "It's possible that we did not have enough statistical power."
He says, too, that the study looked only at the effect of fiber.
Overall, the link found between fiber intake and risk reduction was small. Aune's team found a 10% risk reduction in colorectal cancer for each 10 grams of fiber eaten a day. However, the more fiber people ate, the more risk reduction was found.
The experts found an association, not cause and effect.
The report is published in the online edition of BMJ.
More than 141,000 new cases of colorectal cancer are expected in the U.S. this year, according to the American Cancer Society.
Total dietary fiber and whole grains have already been established as protective against cardiovascular disease, the researchers write.
However, the link with colorectal cancer risk reduction is not as convincing, Aune says. So his team combed through the medical literature. They found 25 scientifically sound studies. They analyzed the data from all of them.
They compared groups from the studies with the highest intake of fiber daily with groups with the lowest intake, Aune tells WebMD.
The amount of fiber eaten by those who had the highest and lowest levels varied from study to study. When the researchers compared groups with the lowest fiber intake with those who ate more, they found each 10-gram a day increase in total fiber and cereal fiber was linked with a 10% reduction in colorectal cancer risk.