Stephen J.D. O'Keefe 1 , Jia V. Li 5 , Leo Lahti 6 , Junhai Ou 1 , Franck Carbonero 7 , Khaled Mohammed 1 , Joram M Posma 5 , James Kinross 5 , Elaine Wahl 1 , Elizabeth Ruder 4 , Kishore Vipperla 1 , Vasudevan Naidoo 8 , Lungile Mtshali 8 , Sebastian Tims 6 , Philippe G.B. Puylaert 6 , James DeLany 3 , Alyssa Krasinskas 2 , Ann C. Benefiel 7 , Hatem O. Kaseb 1 , Keith Newton 8 , Jeremy K. Nicholson 5 , Willem M. de Vos 6 , H. Rex Gaskins 7 , Erwin G. Zoetendal 6
28 April 2015
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 fiber 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 fiber in this association. We performed two-week food exchanges in subjects from the same populations, where African Americans were fed a high-fiber, lowfat African-style diet, and rural Africans a high-fat low-fiber western-style diet under close supervision. In comparison to 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.