Blackmores Institute

Investigating the relationship between levels of vitamin D and gut microbiome in over 500 older men. The study found strong correlations between the vitamin D metabolites, 1,25 (OH)2D and 24,25(OH)2D, and gut microbiome diversity, which is a strong indication of lower risk factors for major diseases and having a “healthier state.” “When examining those with the highest levels of each of the vitamin D measures compared to those with the corresponding lowest levels, men with the highest 1,25(OH)2D and/or activation ratios were more likely to harbor specific genera known to be butyrate producers, or to provide the substrate for bacteria that produce butyrate.” the authors reported. “Notably, 1,25(OH)2D levels exhibited a much greater effect size on α-diversity than these other covariates. Similar findings were found with 1,25(OH)2D and β-diversity. Strikingly, 25(OH)D was not strongly associated with any microbiota measures, whether assessing α-diversity, β-diversity, or specific stool sub-Operational Taxonomic Units. “Serum 25(OH)D is the preferred clinical measure used because it is representative of overall body stores of vitamin D; however, our results suggest that it is the regulation of vitamin D metabolites, reflected by the active hormone and metabolic ratios rather than body stores that may have the most health implications,” the authors said. Previous studies indicate that gut microbiota can alter the metabolism of vitamin D in the intestine and that circulating vitamin D levels can be affected by probiotic supplements. The researchers suggest that the human gut microbiome and vitamin D are integrally related. “These [previous] findings are of major clinical interest because multiple large epidemiological studies have shown that persons with low serum vitamin D levels are at increased risk of multiple adverse health outcomes, including osteoporosis, obesity, inflammatory bowel disease, incident diabetes, cardiovascular disease, cancer, and autoimmune diseases.” According to the study, the significant correlation between amplified vitamin D activation and greater individual stool microbial diversity supports the idea that increased microbial diversity reflects a healthy state. “In the healthy colon, butyrate-producing bacteria including Firmicutes provide enterocytes with short-chain fatty acids for energy production. Indeed, loss of butyrogenic bacteria and decreased overall diversity have both been associated with nosocomial diarrheal illness.” “Thus, in totality, our study findings support previous study assertions of a dynamic interplay between the active vitamin D metabolites and butyrate-producing bacteria. We hypothesize that butyrate-producing colonic microbiota stimulates the local production of 1,25(OH)2D by colon-resident immune cells (e.g., dendritic cells).” Noting the limitations of the cross-sectional study design with respect to identifying causality, the limited taxonomic classifications of the microbiome and the need for further studies, the researchers claim their study still provides strong evidence of important interactions between vitamin D and the health of the gut microbiome in older men. “The consistency and robustness of results in finding active vitamin D metabolites associated with more favourable gut microbial diversity, including specific microbiota that are known butyrate producers, provide potential targets for intervention, whether through dietary modification and/or vitamin D supplementation in clinically appropriate populations,” the authors concluded.Source:
 Thomas, R.L., et al.: Vitamin D metabolites and the gut microbiome in older men. Nat Commun 11, 5997 (2020). <a href="https://www.nature.com/articles/s41467-020-19793-8" target="_blank">https://doi.org/10.1038/s41467-020-19793-8</a>

Higher levels of vitamin D metabolites may be linked to greater diversity in the gut microbiome, according to a recent US study published in Nature Communications.

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