Research

Associations between dietary habits and body mass index with gut microbiota composition and fecal water genotoxicity: an observational study in African American and Caucasian American volunteers

Volker Mai¹ , Quintece M McCrary² , Rashmi Sinha³ and Michael Glei⁴

¹  Microbiology and Cell Science, Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA

²  Food Science and Technology, University of Maryland Eastern Shore, Princess Anne, MD, USA

³  DCEG, National Cancer Institute, Bethesda, MD, USA

⁴  Institute for Nutrition, Department for Nutritional Toxicology, Friedrich-Schiller-University, Jena, Germany

author email corresponding author email

Nutrition Journal 2009, 8:49doi:10.1186/1475-2891-8-49

Published:	21 October 2009

Abstract

Background

African Americans (AA) suffer from an increased incidence and mortality of colorectal cancer (CRC). Environmental exposures including dietary habits likely contribute to a high burden of CRC, however, data on the dietary habits of AA is sparse. Diet might change the composition and the activities of the intestinal microbiota, in turn affecting fecal genotoxicity/mutagenicity that is thought to be associated with carcinogenesis.

Methods

We assessed dietary habits by food frequency questionnaire and by food records in 52 AA and 46 CA residents of the Eastern Shore of MD. Fecal microbiota composition was determined using 16S rRNA based methods and fecal genotoxicity measured using the Comet assay.

Results

AA reported an increased intake of heterocyclic amines and a decreased dietary intake of vitamins including vitamin D (p < 0.05) that correlated with differences in fecal microbiota composition but not fecal genotoxicity. Intake of dietary fiber, calcium, total fat and heterocyclic amines correlated with differences in microbiota composition. Total bacterial counts/g of stool and raw counts of Bacteroides were increased in AA. In contrast to a previous study, BMI was not associated with proportions of Bacteroides.

Conclusion

Dietary habits of African Americans, including increased HCA intake and decreased vitamin D intake might at least partially contribute to CRC through modifications of gut microbiota composition that result in changes of the intestinal milieu.