Vitamin D supplements do not strengthen bones or protect children with vitamin D deficiency from fractures, according to a large clinical trial undertaken by the Harvard T.H. Chan School of Public Health and Queen Mary University of London. The results refute commonly accepted beliefs about how vitamin D affects bone health.

Before they become 18, over one-third of kids will suffer at least one fracture. This is a major global health issue, as childhood fractures can lead to life years of disability and/or poor quality of life. Because vitamin D helps to promote bone mineralization, there has been an increasing amount of interest in the possibility that taking supplements of the vitamin could strengthen bones. However, there have never before been any clinical studies done to see if vitamin D supplementation can shield kids from bone fractures.