Diet swap has dramatic effects on colon cancer risk

CANCER DIGEST – May 5, 2015 – The relationship between dietary fiber and colorectal cancer has been confirmed in many research studies, however a new study suggests the role of fiber in preventing cancer may be even greater than had been thought.

The new study, published in Nature Communications last week, shows that bacteria living in the gut play an  important role in this effect and that fiber has a rapid affect on the microenvironment supporting gut bacteria.

In the small study, the researchers from the University of Pittsburgh and Imperial College London compared dietary effects of 20 volunteers from rural South Africa to a similar group of 20 African Americans. All had undergone colonoscopy with laboratory analysis of biological markers for cancer before the diet swap.

At the start, when the groups had been eating their normal diets, almost half of the American subjects had polyps -- abnormal growths in the bowel lining that may be harmless but can progress to cancer. None of the Africans had these abnormalities.

After two weeks on the African diet, the American group had significantly less inflammation in the colon and reduced biomarkers of cancer risk. In the African group, measurements indicating cancer risk dramatically increased after two weeks on the western diet.

“The findings suggest that people can substantially lower their risk of colon cancer by eating more fiber,” said Professor Jeremy Nicholson team leader from the Department of Surgery and Cancer at Imperial College London in a press release. “This is not new in itself but what is really surprising is how quickly and dramatically the risk markers can switch in both groups following diet change.”

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