Wintertime vitamin D supplementation inhibits seasonal variation of calcitropic hormones and maintains bone turnover in healthy men.
Viljakainen HT, Väisänen M, Kemi V, Rikkonen T, Kröger H, Laitinen EK, Rita H, Lamberg-Allardt C.
J Bone Miner Res. 2009 Feb;24(2):346-52.
PMID: 18847321