The gastrointestinal tract houses a particularly diverse microbial community, so called "microbiota". Variability in the gut microbiota has been linked to many diseases. Because the microbiota is easily modifiable, this could have major therapeutic impact. In particular, it has been shown that serum vitamin D might influence disease risk by modifying the composition of the gut microbiota. This would be the first interventional study on gut microbiota analysis following vitamin D supplementation in vitamin D deficient postmenopausal women. Moreover, the secondary outcome will be to assess biochemical modification of the players of bone metabolism such as PTH, 25(OH)D, 1,25(OH)2D, calcium and phosphorus after cholecalciferol supplementation to investigate their possible correlation with the modification of the microbiota. We decided to utilize two commonly prescribed dosages of vitamin D (25.000 or 50.000 IU per week) as suggested by the guidelines and also to observe if there are any differences between them as regards microbiota modification.
The effects of vitamin D in the setting of microbiota modulation has several clinical implications:
- The first is that the results could possibly elucidate if the commonly prescribed doses of vitamin D influence microbiota, and this finding would shed light on extraskeletal effect of vitamin D.
-Secondly, the study will aim to observe if different baseline microbiota will modulate the response of PTH and calcium to vitamin D supplementation. Thus, these results will support further research as regards both the comprehension of vitamin D effects on some aspects of the microbiota and the understanding whether microbiota is one of the players that influence inter-individual differences in PTH and calcium response to vitamin D supplementation