There are reports that vitamin D supplementation increases blood fibroblast growth factor-23 (FGF23) level, which may negatively affect muscle and bone health. We determined the effect of 4000 IU/day of vitamin D3 for 12 months on circulating FGF23 levels.
We found that in obese older adults with sufficient vitamin D status and normal renal function, vitamin D3 at 4000 IU/day for 12 months did not significantly alter plasma intact FGF23 levels. In all participants combined, the achieved serum 25(OH)D level at month 12 was not significantly associated with the month 12 plasma FGF23 or the month 12 change in FGF23.
The results provide reassurance that daily dosing of vitamin D at doses as high as the upper limit assigned by the National Academy of Medicine (4000 IU per day) does not increase circulating levels of FGF23.
The manuscript is published in the Aging Clinical and Experimental Research
