Vitamin D Supplements Do Not Reduce Fracture Risk in Older Adults

Meryl LeBoff, MD

New data from an ancillary study of the Vitamin D and Omega-3 Trial (VITAL) may close the book on vitamin D3 supplementation for reducing fracture risk for good.

An analysis of data from the randomized, controlled trial, results of the ancillary study demonstrate vitamin D3 supplementation among older adults in the US did not contribute to a reduction in risk of fractures compared to placebo therapy among adults without vitamin D deficiency, low bone mass, or osteoporosis.

“Overall, the results from this large clinical trial do not support the use of vitamin D supplements to reduce fractures in generally healthy US men and women,” said lead investigator Meryl LeBoff, MD, chief of the Calcium and Bone Section in the Endocrine Division at Brigham and Women’s Hospital, in a statement. “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.”

Despite being among the most commonly used supplements for purported benefits in bone health and other areas, data surrounding the benefits versus harms of vitamin D supplementation have failed to return a conclusive stance for or against their use. With this in mind, the VITAL trial, which is sponsored by multiple organizations including the National Heart, Lung, and Blood Institute, was launched in 2010, enrolled 25,871 US adults, and included a 5-year intervention phase assessing whether supplemental vitamin D3 at 2000 IU per day, omega-3 fatty acids at 1 gram per day, or both would prevent cancer and cardiovascular disease in men 50 years of age or older and women 55 years of age or older.

Results of the VITAL trial concluded none of the approaches examined within the trial provided a meaningful reduction in risk of primary cardiovascular disease or cancer vents during the follow-up period. Since results were initially presented in 2018, the trial’s dataset has been used to examine the impact of vitamin D3 supplementation on other outcomes. In the current study, LeBoff and a team of colleagues sought to evaluate whether supplementation impacted total, non-vertebral, or hip fracture risk in older adults, which were used as the primary outcomes of interest for the investigators’ analyses. These end points were assessed using proportional-hazards models that estimated the treatment effect in intention-to-treat analyses.

In the VITAL trial, Investigators identified 1991 occurrences of incident fracture among 1551 participants during a follow-up period lasting a median of 5.3 years. Upon analysis, results indicated vitamin D3 supplementation was no associated with a significant decrease in risk of total fracture, with 769 fractures occurring among 12,927 participants in the vitamin D group and 782 of 12,944 participants in the placebo group (HR 0.98 [95% CI< 0.89-1.08]; P=.70). Further analysis pointed to a similar trend for risk of nonvertebral fractures (HR, 0.97 [95% CI, 0.87-1.07]; P=.50) and hip fractures (HR, 1.01 [95% CI, 0.70-1.47]; P=.96).

Investigators pointed out there was no treatment modification observed based on characteristics, including age, sex, race or ethnic group, body-mass index, or serum 25-hydroxyvitamin D levels. Additionally, no substantial between-group differences were noted for occurrence of adverse events in the trial.

“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,” added JoAnn Manson, MD, study investigator and chief of the Division of Preventive Medicine at Brigham and Women’s Hospital, in the aforementioned statement.

This study, “Supplemental Vitamin D and Incident Fractures in Midlife and Older Adults,” was published in the New England Journal of Medicine.