Q&A: Vitamin D and Bone Mineral Density

Lauren Burt, Ph.D., University of Calgary

High-dose vitamin D supplementation compared with standard-dose vitamin D supplementation resulted in a greater loss of volumetric bone mineral density in women but not men, according to a study presented on Sept. 11 at the American Society for Bone and Mineral Research (ASBMR) annual meeting which is being held virtually this week.

In this Q&A, author Lauren Burt, Ph.D., a senior scientist at McCaig Institute for Bone & Joint Health, University of Calgary, highlights the findings of this three-year study. 311 healthy males and females (55-70 years) were randomly assigned to receive vitamin D supplementation for three years at a dose of 4,000 IU, 10,000 IU per day, or 400 IU per day. After three years, females lost 1.8 percent (400), 3.8 percent (4000) and 5.5 percent (10,000) of volumetric bone mineral density, whereas males lost 0.9 percent (400), 1.3 percent(4000) and 1.9 percent(10,000) at the radius. At the tibia, losses in volumetric bone mineral density were smaller, but followed a similar trend.

What are the main takeaways from the study?

"We found vitamin D at a dose of 4,000 IU or 10,000 IU per day, compared with 400 IU per day, resulted in greater losses of volumetric bone mineral density, in females. However, in males, there was no dose-response effect of vitamin D supplementation on volumetric bone mineral density.

If you have normal bone density and adequate levels of vitamin D, there is no bone benefit in taking doses of vitamin D above the standard recommendations designed to prevent vitamin D deficiency; and that doses at or above 4000 IU/day might even be detrimental to bone, especially in females.

However, due to the exploratory post-hoc analysis, the possibility of high dose vitamin D causing harm needs further investigation."

How can the findings help clinicians and patients?

"These results are clinically relevant, as vitamin D supplementation is widely administered to postmenopausal females for osteoporosis prevention. These findings raise the possibility that in vitamin D-sufficient females, additional high dose vitamin D supplementation might have a detrimental effect on bone."

What are the limitations of the findings?

"It is important to emphasize this was an exploratory outcome from our clinical trial. We were not powered to look at the differences between sex in our primary analysis. Different results may be observed in osteoporotic or vitamin D deficient individuals. Further research is needed to determine whether high-dose vitamin D is harmful to bone, particularly for females.​" ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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For more news from the annual ASBMR meeting, visit our conference page.

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REFERENCE

Lauren A. Burt,Emma O. Billington, Marianne S. Rose, et al. Effect of High-Dose Vitamin D Supplementation on Volumetric Bone Density and Bone Strength: A Randomized Clinical Trial.JAMA. August 27, 2019. doi:10.1001/jama.2019.11889

Lauren A. Burt,Emma O. Billington, Marianne S. Rose, et al. High-dose Vitamin D Supplementation Affects Bone Density Differently in Females than Males.Journal of Bone and Mineral Research. August 10, 2020. https://doi.org/10.1002/jbmr.4152