Data from: Fat, fibre and cancer risk in African Americans and rural Africans

Rates of colon cancer are much higher in African Americans (65:100,000)
than in rural South Africans (<5:100,000). The higher rates are
associated with higher animal protein and fat, and lower fibre
consumption, higher colonic secondary bile acids, lower colonic
short-chain fatty acid quantities and higher mucosal proliferative
biomarkers of cancer risk in otherwise healthy middle-aged volunteers.
Here we investigate further the role of fat and fibre in this association.
We performed 2-week food exchanges in subjects from the same populations,
where African Americans were fed a high-fibre, low-fat African-style diet
and rural Africans a high-fat, low-fibre western-style diet, under close
supervision. In comparison with their usual diets, the food changes
resulted in remarkable reciprocal changes in mucosal biomarkers of cancer
risk and in aspects of the microbiota and metabolome known to affect
cancer risk, best illustrated by increased saccharolytic fermentation and
butyrogenesis, and suppressed secondary bile acid synthesis in the African
Americans.