African-Americans and Africans who swapped diets for only two weeks were found to exchange their colon cancer risks.
The risk of colon cancer in among these individuals was determined by looking at gut bacteria, the University of Pittsburgh School of Health Sciences reported. The researchers observed rural South African patients rarely had colon cancer or intestinal polyps, but in the U.S. colon cancer is the second leading cause of cancer death.
"The African-American diet, which contains more animal protein and fat, and less soluble fiber than the African diet, is thought to increase colon cancer risk," said principal investigator Stephen O'Keefe, M.D., professor of medicine, Division of Gastroenterology, Hepatology and Nutrition, Pitt School of Medicine. "Other studies with Japanese migrants to Hawaii have shown that it takes only one generation of Westernization to change their low incidence of colon cancer to the high rates observed in native Hawaiians. In this project, we examined the impact of a brief diet change on the colon in a controlled setting where we didn't have to worry about the influence of smoking and other environmental factors on cancer risk."
The research team looked at 20 African-American and 20 rural South African volunteers between the ages of 50 and 65. The participants were served meals using ingredients typically consumed by the opposite groups. The team examined fecal and colon content samples collected during colonoscopies following a two week study period.
Despite the exceptionally short study period, each group were found to exhibit the others rate of turnover of cells in the intestinal lining, fiber fermentation levels, and markers of bacterial metabolic activity and inflammation associated with cancer risk. African-Americans showed an increase in butyrate production, which has been linked to anti-cancer pathways.
"We can't definitively tell from these measurements that the change in their diet would have led to more cancer in the African group or less in the American group, but there is good evidence from other studies that the changes we observed are signs of cancer risk," said co-author Jeremy Nicholson, Ph.D., of Imperial College London.
The researchers suggested increasing the amount of dietary fiber from about 10 percent to more than 50 percent in the African American group may have been the key.
"These findings are really very good news," O'Keefe said. "In just two weeks, a change in diet from a Westernized composition to a traditional African high-fiber, low-fat diet reduced these biomarkers of cancer risk, indicating that it is likely never too late to modify the risk of colon cancer."
The findings were published in a recent edition of the journal Nature Communications.
