Impact of Vitamin D Supplementation on Indole-Producing Bacterial Species Abundance in the Human Gut Microbiome
Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the second most common cause of cancer mortality worldwide. With an increasing rate of diagnosis in adults under 50, a better understanding of the CRC risk factors is needed. Research demonstrates that serum vitamin D can reduce cancer risk by improving immune function, and it is hypothesized that the bacterial species and their metabolites, including indole, may control vitamin D response. Vitamin D supplementation's effect on indole production in the microbiome was evaluated in a randomized double-blind control study with 42 participants for 12 weeks. Using the bioinformatic tool PICRUSt we transformed microbial data to identify tryptophan microbial pathways. While there were individualized changes in the microbiome, none of these changes in indole-producing bacterial species or tryptophan microbial pathways were significantly correlated with vitamin D serum level changes. This data suggests that microbiome changes due to vitamin D are highly individualized.