High Dose Vitamin D and Your Bones

Up to 10,000 IU per day is proven safe

Vitamin D plays a vital role in overall health, everything from building strong teeth and bones to warding off chronic disease and alleviating depression.

A three-year, double-blind, randomized controlled study from from the University of Calgary Cumming School of Medicine, funded by Pure North and led by Drs. David Hanley and Steven Boyd, focused on how different levels of vitamin D supplementation affect bone health.

Researchers tested the bone mineral density (BMD) and bone strength of participants, aged 55 to 70, in three groups: the first group took 400 IUs of vitamin D per day; the second 4,000 IUs; and the third 10,000 IUs.

After three years, the researchers found a statistically significant loss of bone density for those taking the two higher doses, but no change in bone strength. There were no differences between groups for safety, including vascular calcification.

Hanley and Boyd share some key takeaways from their study, recently published in the Journal of the American Medical Association.

World-Class Research

Bone density and strength were measured using a high-resolution computed topography scan, called an XtremeCT. Allan Markin, Pure North’s founder, donated the funds for the purchase. Not only was this equipment state-of-the-art, but it helped leverage $13 million in funding for the U of C’s McCaig Institute for Bone and Joint Health, a clinical research facility. The institute even uses the XtremeCT to assess the bones of NASA’s astronauts.

The Expectations

“We wanted to test the hypothesis that pushing the dose of vitamin D higher than what is usually used might have some further beneficial effect for bone,” says Hanley, an endocrinologist. “The Xtreme CT allows for calculation of bone strength, and despite the decline in bone density measurements with the higher doses, there was no significant reduction in bone strength … and no differences in fractures.”

In fact, the bone mineral density changes picked up by the XtremeCT were not detected using the traditional equipment, Dual X-Ray Absorptiometry or DEXA.
The Implications: “The main message was, there’s clearly no bone benefit for higher dosages,” says Hanley. “If you’re taking 10,000 IUs for the sake of your bones, you don’t need to. But we didn’t address the other areas of potential vitamin D benefits.”

“People should have their vitamin D levels checked”
– Dr. David Hanley

Given that some may need higher vitamin D levels for everything from cardiovascular disease and depression to autoimmune and absorption issues, Hanley says “people should have their vitamin D levels checked.” That’s in keeping with Pure North’s commitment to measurement and tracking, focusing on participants’ individual needs.

The Future

“This study will take a long time to analyze still,” says Boyd, adding that papers have been written on such secondary outcomes as safety (no differences between dose groups), adverse effects (no differences) and calcium buildup in the arteries (no differences), plus determining what the changes in bone density were using the wealth of data provided by the XtremeCT.
“The impact on your bones is small but significant,” says Boyd, a mechanical engineer and director of the McCaig Institute.

As for scaring people away from taking vitamin D, Dr. Hanley reminds us: “There is a continuing need to prevent vitamin D deficiency,” he says. His advice? Work with a health care professional to “find out what’s right for you.”