Investigating the Relationship Between Vitamin D and Incident Fractures

Meryl S. LeBoff, MD

In the US, an estimated 53.6 million people have osteoporosis, low bone mass, or both, with 2 million osteoporotic fractures occurring each year. According to a new study, the number of annual osteoporotic fractures are projected to surpass 3 million by 2040. Related costs will escalate to more than $95 billion.

Meryl S. Leboff, MD, Brigham and Women’s Hospital, and an investigative team conducted a trial that evaluated the supplemental vitamin D3, n-3 fatty acids, or the combination of both, to determine if they could prevent cancer and cardiovascular disease. The team specifically focused on men 50 years and older, and women 55 years and older in the US.

Vitamin D supplements are often recommended for the improvement of bone health, but investigators said the data are unclear whether they prevent fractures.

The VITAL Study

For the Vitamin D and Omega-3 Trial (VITAL), the primary end points were incident total, nonvertebral, and hip fractures. Proportional-hazards models were used to estimate the treatment effect in intention-to-treat analyses.

Supplemental vitamin D³ was tested to see if it would result in a lower risk of fractures when compared with placebo. The two-by-two factorial, randomized, controlled trial provided paricipants supplemental vitamin D³ (2000 IU per day), n−3 fatty acids (1 g per day), or both.

Vitamin D deficiency, low bone mass, or osteoporosis was not the basis of recruitment. Participants reported incident fractures on annual questionnaires and the reports were adjudicated by centralized medical-record review.

The Outcomes

"Vitamin D3 supplementation did not result in a significantly lower risk of fractures than placebo among generally healthy midlife and older adults who were not selected for vitamin D deficiency, low bone mass, or osteoporosis," investigators stated.

A total of 1991 incident fractures were confirmed in 1551 participants over a median follow-up of 5.3 years. There was no significant improvement with vitamin D when compared with placebo for its impact on total fractures.

There was no modification of the treatment effect according to baseline characteristics, including age, sex, race or ethnic group, body-mass index, or serum 25-hydroxyvitamin D levels. Between-group differences in adverse events, as assessed in the parent trial, were not substantial.

"Findings were similar for secondary end points, which excluded toe, finger, skull, periprosthetic, and pathologic fractures. We also found no effect of supplemental vitamin D³ as compared with placebo on major osteoporotic fractures and other exploratory end points, including pelvic and wrist fractures," investigators wrote.

The study, "Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults" was published in The New England Journal of Medicine.