VITAMIN D SUPPLEMENTS DO NOT REDUCE THE RISK OF BONE FRACTURES, at least among adults in midlife and older adults. That is the conclusion of an ancillary study of the Vitamin D and Omega-3 Trial (VITAL).
Vitamin D serves many important body functions. For example, it helps to keep our bones strong by helping our bodies absorb calcium and phosphorus. Our muscles use vitamin D to move, and nerves need it to carry messages.
Many of my patients take vitamin D (often without vitamin K). But do vitamin D supplements prevent bone breaks (fractures)? While some studies show a benefit to supplementing vitamin D, others show no benefit (or even harm). Today we look at a new study that provides some answers.
Vitamin D and fractures: the study
Researchers note that the available clinical literature regarding vitamin D supplementation and bone fractures shows mixed results. Here’s how a study author puts the new study in context:
“We previously reported that vitamin D, about 2000 units per day, did not increase bone density, nor did it affect bone structure, according to CT scans. So that was an indicator that since bone density is a surrogate marker of fractures, there may not be an effect on fractures.”
Scientists analyzed over 25,000 subjects from all 50 states in the United States. The researchers randomly assigned them to receive either vitamin D or a placebo.
The participants had an average age of 67 years, with half being women and 20 percent Black. None of the subjects had osteoporosis, low bone mass, or vitamin D deficiency. Each participant agreed not to supplement their dietary intake with more than 800 IU of vitamin D and 1200 milligrams of calcium daily.
Researchers collected survey information, including baseline prescription drug use, medical history, demographics, and supplement consumption. The subjects completed annual surveys looking at compliance to the research protocol, falls, fractures, physical activity, osteoporosis, major illnesses, and non-trial prescription drugs and supplements (including calcium and vitamin D).
Supplemental vitamin D and fractures: results
The scientists then identified fracture data using a central medical record review. Here are the research findings:
- The placebo and vitamin D groups had similar incidences of high calcium levels (hypercalcemia) and kidney stones.
- Vitamin D3 supplementation did not lead to a lower risk of bone fractures (than placebo) among healthy middle age and older adults not selected for low bone mass, vitamin D deficiency, or osteoporosis.
- No subgroups, classified based on baseline vitamin D levels (including those with very low levels), benefited from vitamin D supplementation.
In a phone interview with Medscape, Case Western Reserve (USA) expert observes that “there is no justification for measuring 25-hydroxyvitamin D in the general population or treating to a target serum level. A 25-hydroxyvitamin D level might be a useful diagnostic test for some patients with conditions that may be due to or that may cause severe deficiency.”
My take — Supplemental vitamin D
This is an important study, but there it has some limitations.
The researchers did not add vitamin K to the vitamin D supplementation. In addition, the study used only one dose of vitamin D supplements. In addition, the investigation had few subjects with vitamin D deficiency, given concerns about potentially randomizing such patients to the placebo group.
The study results don’t apply to those who are older, institutionalized, or with conditions such as profound bone loss (osteoporosis). The research paper references folks who may benefit from vitamin D supplementation, including those who are deficient in it. Extremely low levels can lead to weak bones, for example.
Finally, there are some potential conflicts of interest. While the National Institute of Arthritis and Musculoskeletal and Skin Diseases sponsored the study, Pharmavite donated the vitamin D3 supplements.
One study author reports that she holds stock in Amgen, and another gets personal fees and non-financial support from Amgen outside the submitted work.
What can you do to improve bone health? Here is what I previously wrote:
Thank you for joining me today in this look at vitamin D supplementation and bone fractures.
The information I provided in this blog is for educational purposes only and does not substitute for professional medical advice. Please consult a medical professional or healthcare provider if you seek medical advice, diagnoses, or treatment. I am not liable for risks or issues associated with using or acting upon the information in this blog.
