Colonic Mucosal Bacteria Are Associated with Inter-Individual Variability in Serum Carotenoid Concentrations

Publication date: Available online 21 December 2017
Source:Journal of the Academy of Nutrition and Dietetics
Author(s): Zora Djuric, Christine M. Bassis, Melissa A. Plegue, Jianwei Ren, Rena Chan, ElKhansa Sidahmed, D. Kim Turgeon, Mack T. Ruffin, Ikuko Kato, Ananda Sen
BackgroundRelatively high serum carotenoid levels are associated with reduced risks of chronic diseases, but inter-individual variability in serum carotenoid concentrations is modestly explained by diet. The bacterial community in the colon could contribute to the bioaccessibility of carotenoids by completing digestion of plant cells walls and by modulating intestinal permeability.ObjectiveTo evaluate whether colonic bacterial composition is associated with serum and colon carotenoid concentrations.DesignThe study was a randomized dietary intervention trial in healthy individuals who were at increased risk of colon cancer. Colon mucosal biopsy samples were obtained before and after 6 months of intervention without prior preparation of the bowels.Participants/settingParticipants were recruited from Ann Arbor, MI, and nearby areas from July 2007 to November 2010. Biopsy data were available from 88 participants at baseline and 82 participants after 6 months.MethodsStudy participants were randomized to counseling for either a Mediterranean diet or a Healthy Eating diet for 6 months.ResultsAt baseline, bacterial communities in biopsy samples from study participants in the highest vs the lowest tertile of total serum carotenoid levels differed by several parameters. Linear discriminant analysis effect size identified 11 operational taxonomic units that were significantly associated with higher serum carotenoid levels. In linear regression analyses, three of these accounted for an additional 12% of the variance in serum total carotenoid concentrations after including body mass index, smoking, and dietary intakes in the model. These factors together explained 36% of the inter-individual variance in serum total carotenoid concentrations. The bacterial community in the colonic mucosa, however, was resistant to change after dietary intervention with either a Mediterranean diet or Healthy Eating diet, each of which doubled fruit and vegetable intakes.ConclusionsThe colonic mucosal bacterial community was associated with serum carotenoid concentrations at baseline but was not appreciably changed by dietary intervention.



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