Supplemental vitamin D did not lower risk of fractures in healthy US adults

Although vitamin D supplements are widely prescribed and used to benefit bone health, definitive data on whether these supplements reduce fractures in the general population have been inconsistent. To advance scientific understanding on this subject, a team of researchers at Brigham and Women’s Hospital conducted an ancillary study to the VITamin D and OmegA-3 TriaL (VITAL), a clinical trial of more than 25,000 adults, also led by investigators from the Brigham. A total of 1,991 incident fractures in 1,551 participants were confirmed over a median follow-up of 5.3 years. Compared to placebo, supplemental vitamin D₃ (2000 IU/day) did not reduce total, non-vertebral, or hip fractures. The analyses also showed that there were no effects of supplemental vitamin D₃ on major osteoporotic fractures, wrist fractures, or pelvic fractures. Effects were not modified by baseline age, sex, race, body mass index, baseline vitamin D blood levels, and personal use of supplemental calcium and/or vitamin D.

“Overall, the results from this large clinical trial do not support the use of vitamin D supplements to reduce fractures in generally healthy U.S. men and women,” said lead author Meryl LeBoff, MD, Chief of the Calcium and Bone Section in the Endocrine Division at the Brigham. “These findings do not apply to adults with vitamin D deficiency or low bone mass or osteoporosis. Most participants in the trial were not deficient and may have already reached the vitamin D level needed for bone health. Our ongoing studies are focusing on whether free vitamin D levels or genetic variation in vitamin D absorption, metabolism, or receptor function will provide information about individuals who may benefit from supplemental vitamin D on musculoskeletal health.”

 JoAnn Manson, MD, co-author and chief of the Division of Preventive Medicine at the Brigham said, “Although VITAL was originally designed to look at cardiovascular and cancer outcomes, this is a wonderful example of how it has shed light on health outcomes far beyond its original goals.”

Read more in The New England Journal of Medicine.