Vitamin D plays an essential role in bone health, and low levels of the vitamin may contribute to the development of osteoporosis. But experts disagree on the optimal level of vitamin D for musculoskeletal health.
A new study published online by JAMA Internal Medicine examines this question in detail, comparing the effects of placebo, low-dose cholecalciferol (a form of vitamin D) and high-dose cholecalciferol taken over the course of one year.
Dr. Karen E. Hansen of the University of Wisconsin School of Medicine and Public Health, and colleagues, examined 230 postmenopausal women (aged 75 years or younger) with vitamin D insufficiency and no osteoporosis. They looked at one-year changes in total fractional calcium absorption, bone mineral density, sit-to-stand tests and muscle mass.
Trial participants were divided into three groups. Those in the first group were given daily white and twice monthly yellow placebo. The low-dose vitamin D group were given daily 800 IU vitamin D3 and twice monthly yellow placebo, while the high-dose group took a daily white placebo and twice monthly 50,000 IU vitamin D3.
Some experts contend that optimal serum 25-hydroxyvitamin D levels are 30 ng/mL or greater. The high-dose vitamin D regimen in this study achieved and maintained 25-hydroxyvitamin D levels at greater than or equal to 30 ng/mL.
Results showed that the high-dose therapy increased calcium absorption, but the effect was small and did not translate into beneficial effects on bone mineral density, muscle function, muscle mass or falls.
The study authors said that they found no data to support experts´ recommendations to maintain 25-hydroxyvitamin D levels at 30 ng/mL or higher in postmenopausal women. Instead, this research suggests that low- and high-dose cholecalciferol were equivalent to placebo in their effects on bone and muscle outcomes.
In a related Editor´s Note, Dr. Deborah Grady, a deputy editor of JAMA Internal Medicine, said: “It is possible that treatment beyond one year would result in better outcomes, but these data provide no support for use of higher-dose cholecalciferol replacement therapy or indeed any dose of cholecalciferol compared with placebo.”