Randomized clinical trials of vitamin D and bone health

Vitamin D supplementation is commonly recommended in clinical practice to improve bone health. However, evidence from randomized clinical trials (RCTs) on the effects of supplemental vitamin D on bone density and fracture outcomes have been inconsistent. RCTs investigating effects of vitamin D supplementation on fracture risk have mostly shown no benefit, a few with benefit, and even some demonstrating potential harm. Although adequate vitamin D and calcium intakes are safe and considered good clinical practice in patients at high risk of fracture, data from the new large RCTs, including VITamin D and OmegA-3 TriaL (VITAL) and DO-HEALTH trial, do not support the use of supplemental vitamin D alone to prevent loss of bone density or reduce fracture risk in the generally healthy population not preselected for vitamin D deficiency or low bone mass.