Just how important is a healthy diet for reducing colon cancer risk? A new study, published in Nature Communications, concludes in a dramatic way that it is very important. The study enrolled 20 South Africans who eat a high-fibre, low-fat African-style diet, and 20 African Americans who eat a low-fibre, high-fat Western-style diet. Researchers then switched the diets of the two groups under tightly controlled conditions for two weeks: those from South Africa received a Western-style diet (high-fat and low-fibre), and those from the US received an African-style diet (low-fat and high-fibre). Participants also underwent colonoscopies and researchers tracked various markers of colon cancer risk at the beginning and end of the study. Here are the findings:

• At the start of the study, none of the participants from South Africa had polyps (abnormal growths in the bowel lining that may be harmless or develop into cancer), whereas almost half of those from the US had polyps.
• After two weeks on the African-style diet, the US group had significantly less inflammation in the colon, as well as reduced markers of colon cancer risk.
• After two weeks on the Western-style diet, on the other hand, there were measurements indicating an increased risk for colon cancer in the group from South Africa.
• The changes in both groups appear to be related in part to the way the metabolism of gut bacteria shifted to accommodate the new diets.

The results of the research are important for a couple of reasons. First, they indicate that diet can alter markers of colon cancer risk in even a short amount of time—participants swapped diets for only two weeks, yet researchers observed important physiological changes. Second, African Americans have the highest colon cancer rate in the US (colon cancer is the fourth most common cancer in the world), and the study points to possible dietary strategies to reduce colon cancer risk.

Source: Nature Communications