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Vitamin D. I don't know why so many people are obsessed with it, but there are two new studies out about it in JAMA Internal Medicine. We've even got multiple episodes of Healthcare Triage about it. What's one more? This is Healthcare Triage News.

For those of you who want to read more, go here:

John Green -- Executive Producer
Stan Muller -- Director, Producer
Aaron Carroll -- Writer
Mark Olsen -- Graphics



Dr. Carroll: Our first bit of news is that we've got a Facebook page, It's awesome and it'll make it so much easier for you to share the magic and wonder of Healthcare Triage with all of your Facebook friends.
But you know what else is great -- or not? Vitamin D. I don't know why so many people are obsessed with it, but there are two new studies out about it, just this week, in JAMA Internal Medicine. We've even got multiple episodes of Healthcare Triage about Vitamin D! Want one more? This is Healthcare Triage News.

 First Study

First up is exercise and Vitamin D in fall prevention among older women: a randomized clinical trial. This was a randomized, double-blind, placebo-controlled vitamin and open exercise trial, involving women aged 70 to 80 years living in Finland. The exercise was "open" because you obviously can't blind people to that, but you can to Vitamin D.
So there were four groups: exercise with Vitamin D, exercise with placebo, no exercise with Vitamin D, and no exercise with placebo. The main outcomes of interest were reported falls, falls with injuries, bone density, and physical functioning. And Vitamin D metabolism.
The rates of falls were unaffected by exercise or Vitamin D. They fell at the same rates. However, falls with injuries did differ. In the exercise groups, the rates of falls with injuries were almost halved. Vitamin D, though, had no effect. None. Vitamin D did improve femoral neck bone mineral density and it increased tibial trabecular density a little bit…Okay. Exercise though increased muscle strength and balance.
See here’s the deal. If you want to improve the ways your bones look on a bone scan, then supplement with Vitamin D. If you want to improve your balance, strength, and decrease the chance of your getting injured in a fall however, then exercise. Vitamin D won’t make a difference.

 Second Study

The second study is effect of Vitamin D supplementation on blood pressure. A systematic review in meta-analysis incorporating individual patient data. Honestly, I didn’t even know it was a thing that people considered vitamin D supplementation could reduce high blood pressure. But evidently, lots of people think it’s a miracle pill. So much so that we can do a study of studies on this topic.
This was a systematic review of randomized, placebo controlled clinical trials that involved vitamin D and had data on blood pressure. Both active and inactive forms of vitamin D were considered as well as their analogs. If everyone in this study got Vitamin D though, it was excluded as you couldn’t do a comparison between those that didn’t.
There were 46 trials involving more than 4500 participants. At the trial level, wait for it, Vitamin D supplementation had no effect on either systolic or diastolic blood pressure. No effect. When they looked at the patient level, there were still no significant effects of Vitamin D on blood pressure. When they did subgroup analyses, they could find no baseline predictive factors that might have a better response. In other words, it worked for no one.


Now if you open up a newspaper or go online, you’re going to see lots of studies that say Vitamin D is linked to or associated with a host of issues or good outcomes. Those studies aren’t wrong in the sense that they are cohort or case controlled studies that show a correlation between Vitamin D levels and many diseases.
But those are correlations, and it’s entirely possible that other factors, like socioeconomic status, are related to both Vitamin D levels and health. The way we can see if that correlation is really causation is to conduct prospective trials. Ideally, randomized controlled trials to see if that’s the case.
And we’re worried about bone strength and injuries from falls in the elderly. We’re worried about high blood pressure. It’s totally understandable that we want the correlations we sometimes see with Vitamin D to pan out in actual active therapies.
Unfortunately, in those studies which get done, that rarely seems to be the case. Vitamin D supplementation didn’t lower blood pressure. It also didn’t protect the elderly. But exercise did. That may be harder to pull off than popping a vitamin, but it’s what works.