title: Association between low colonic short-chain fatty acids and high bile acids in high colon cancer risk populations.
abstract: We propose that the influence of diet on colon cancer risk is mediated by the microbiota. To investigate how dietary fat influences risk, we compared the colonic contents of 12 adult high-risk African Americans (AAs) and 10 Caucasian Americans (CAs) who consumed a high-fat diet (123 ± 11 g/d and 129 ± 17 g/d, respectively) to 13 native Africans (NAs) who subsisted on a low-fat (38 ± 3.0 g/d) diet, all aged 50-60 yr. The colonic bile acids were measured by LC-MS and the short-chain fatty acids (SCFAs) by GC. The chief secondary colonic bile acids, deoxycholic acid and lithocholic acid, were correlated with fat intake and similar between AAs and CAs, but 3-4 times higher than in AAs (p < 0.05). The major SCFAs were lower in AAs (p < 0.001) and CAs (p < 0.001) compared to AAs, but conversely, the branched chain fatty acids (BFCA) were higher. Our results suggest that the higher risk of colon cancer in Americans may be partly explained by their high-fat and high-protein, low complex carbohydrate diet, which produces colonic residues that promote microbes to produce potentially carcinogenic secondary bile acids and less antineoplastic SCFAs. The role of BCFA in colonic carcinogenesis deserves further study.
authors.affiliation: Department of Gastroenterology, Hepatology and Nutrition, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Junhai
authors.initials: J
authors.lastname: Ou
authors.forename: James P
authors.initials: JP
authors.lastname: DeLany
authors.forename: Ming
authors.initials: M
authors.lastname: Zhang
authors.forename: Sumit
authors.initials: S
authors.lastname: Sharma
authors.forename: Stephen J D
authors.initials: SJ
authors.lastname: O'Keefe
mesh_terms: D001741:Black or African American; D001647:Bile Acids and Salts / Q000032:analysis*; D019826:Cholic Acid / Q000032:analysis; D003110:Colonic Neoplasms / Q000208:ethnology / Q000209:etiology / Q000378:metabolism*; D003840:Deoxycholic Acid / Q000032:analysis; D059305:Diet, High-Fat; D004041:Dietary Fats / Q000494:pharmacology*; D005232:Fatty Acids, Volatile / Q000032:analysis*; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D008095:Lithocholic Acid / Q000032:analysis; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania; D012307:Risk Factors; D013019:South Africa; D044465:White People
chemical_list: D001647:Bile Acids and Salts; D004041:Dietary Fats; D005232:Fatty Acids, Volatile; D003840:Deoxycholic Acid; D008095:Lithocholic Acid; D019826:Cholic Acid