VitaminDwiki, http://www.vitamindwiki.com/Gut+microbi ... +July+2015 , features the following paper (with graphs, and comments by Dr. Rhonda Patrick):
Effects of high doses of vitamin D3 on mucosa-associated gut microbiome vary between regions of the human gastrointestinal tract. (June 2016)
M Bashir, et al.
https://www.ncbi.nlm.nih.gov/pubmed/26130323
(By the way, I wonder how the gut bacteria mentioned compare with the bacteria in kefir – milk or water – and the bacteria in probiotic capsules. Are they the same? I'll have to check the label on my probiotics.)Conclusion: Vitamin D3 modulates the gut microbiome of the upper GI tract which might explain its positive influence on gastrointestinal diseases, such as inflammatory bowel disease or bacterial infections. The local effects of vitamin D demonstrate pronounced regional differences in the response of the GI microbiome to external factors, which should be considered in future studies investigating the human microbiome.