Studies that do not assess baseline vitamin D status before intervention limit interpretability.

“Numerous studies report outcomes without assessing participants' baseline vitamin D status. This oversight is one common source of confusion, both within the literature and among many interpreting it.”

“A big smoking gun is that many trials fail to establish vitamin D status for participants. Without clearly determining whether participants were deficient or sufficient initially, and without verifying whether the dosage given was adequate to achieve meaningful changes in vitamin D status by follow-up, these studies inevitably produce confounded results and significantly limit the interpretability of their conclusions.”

“They just give them the supplement. And it blows my mind that that can even get past peer review, or how do you design a trial that way?”