Vitamin D and Bone Health – Sifting Through the Science
October 10, 2018
From bolstering the immune system to fostering heart health, vitamin D confers an array of benefits. It also helps the body absorb and retain key minerals like calcium and phosphorus, both critical for building bone.
Recently, a meta-analysis published in the Lancet Diabetes & Endocrinology looked at data from 81 randomized controlled trials to determine how much of an impact vitamin D made on fractures, falls and bone density. While the authors concluded that vitamin d supplementation did not improve bone mineral density or prevent fractures or falls in adults, there are several points of the review to take into consideration.
Test participants:
As CNN noted, only 6% of the trials were done in populations with vitamin D deficiency, exactly the population who would see the most benefit from vitamin d supplementation.
“We know from meta-analyses that have managed to obtain individual participant data that the health benefits of vitamin D supplementation tend to be most marked in people who have the lowest vitamin D levels to start with,” said Adrian Martineau, clinical professor of respiratory infection and immunity at Queen Mary University of London.
Size and concentration:
Reviewers of the meta-analysis noticed that some trials lacked a robust number of participants and inadequate doses of vitamin D.
As Dr. Robert Clarke, professor of epidemiology and public health at the University of Oxford said, “The report included all available trials of vitamin D, but such trials included too few participants, used an insufficient dose of vitamin D, and had an insufficient duration of treatment.”
He also went on to say, “Hence the study lacked the ability to reliably test the effects of vitamin D on risk of hip fracture. So, it is too soon to suggest making changes to health recommendations on vitamin D for bone health based on this study.”
The recommended dietary allowance (RDA) for vitamin D was even recently increased due to the number of studies showing a more significant amount was required. Do note, the RDA value is used to mitigate disease risk factors not for optimizing your health which often requires an even greater concentration.
A separate meta-analysis published in The New England Journal of Medicine found that vitamin D, when taken in higher doses- between 800 and 2000 IUs per day – substantially reduced the likelihood of broken bones in both men and women. This was a review of 11 individual randomized controlled trials all of which focused on the effect of vitamin D supplementation in those over age 65. Among the 31,000 seniors who were taking between 800 to 2000 IU of vitamin D, they found a 30 percent decrease in the risk of hip fractures with a significant decrease in risk of fractures of other bones as well.
Based on this study and a growing body of research, we recommend that you consume about 2000 IU of vitamin D3 per day. Many individuals need more than this to keep their vitamin D levels in a healthy range. Alarmingly, vitamin D deficiency is an epidemic in America, with up to 2 out of 3 Americans having suboptimal levels of this critically important compound (that is actually more of a hormone than a vitamin).
As stated earlier, the populations that see the most benefits are the ones that are the most deficient and who don’t engage in a healthy lifestyle. This is a reason why the conclusion reached by the team compiling the meta-analysis should be taken with caution, "The message of our study is that if you are fit and healthy, you don't need to take vitamin D supplements, and this applies to most people, even those with medical conditions.” - lead author Mark Bolland, associate professor of medicine at Auckland University.
In Good Health,
The Cardiotabs Team
