Some evidence here that the "usefulness" of supplements may be partly (highly?) dependent on gut biome, and thus on the nature of one's diet and other factors that influence microbial diversity:
"... men with the highest compared to lowest 1,25(OH)2D and activation ratios are more likely to possess butyrate-producing bacteria that are associated with favorable gut microbial health. These results support the underlying hypothesis that the human gut microbiome and vitamin D metabolism are integrally related."
"... while sun exposure may affect the storage form of vitamin D, there appears to be less influence on the active hormone."
"The positive association between diversity metrics and vitamin D activation and catabolism ratios suggests that physiologically normal vitamin D flux is more likely to occur in individuals with healthy microbiomes."
So this study seems to help confirm the common-sense notion that just adding pills to a crap diet may not be all that helpful, and suggests that better biomes not only allow for productive use of stored vitamin D but might help prevent toxicity associated with supplementation! One more reason to eat a heart-healthy, whole-food diet that's plentiful in fiber-rich plant foods.
It also partly helps explain why some vitamin D studies might not show the level of benefit that researchers were expecting or hoping for.
nature.com/articles/s41467-...
From an interview regarding the study:
“We were surprised to find that microbiome diversity — the variety of bacteria types in a person’s gut — was closely associated with active vitamin D but not the precursor form,” says senior author of the study Dr. Deborah Kado.
The correlation between microbial diversity and active vitamin D remained even after adjusting for factors known to determine microbial diversity. These included the participants’ age, where in the United States they lived, their ethnic background, and their antibiotic use. In fact, the participants’ levels of active vitamin D correlated much more strongly with microbiome diversity than any of these other factors (i.e., people who live in sunnier places).
Poop talk: microbiome and prostate cancer, some news
