Digging Deeper into a Recent Vitamin D Study

Sigh. Studies that cast doubt on the value of supplements are automatically assumed true and publicized as such. There seems to be a prevalent mindset that humans are poorly designed and cannot function without medications. Ridiculous. We are by nature healthy…if we give the body everything it needs for optimum function and we don’t gum up the works with excesses it cannot handle.

One thing we don’t get enough of for optimum function is vitamin D. The original plan was that we would be functioning most of the time in the sunshine and naturally form vitamin D when the sunlight touched our skin (typically 10,000 IU per day). Modern indoor life and the admonitions of dermatologists to cover up with sunscreen have changed that dramatically. Virtually every cell in our body has a receptor for vitamin D and it interacts with over 3,000 genes. I guess we can assume it must be pretty important. It is being researched, but often in a way that produces misleading results.

For example, a vitamin D study released in November 2018 concludes that 2,000 IU of supplemental vitamin D does not help prevent cardiovascular problems or cancer compared to a placebo. On the plus side, it was very large, randomized, placebo-controlled and fairly long (5.3 years so far). I have these concerns about putting too much stock in the study’s conclusion.

  • They called 2,000 IU a “high” dose. Recent research shows most of us probably need between 7,000 and 10,000 a day to reach optimum blood levels of 70 ng/mL or so.
  • Testing the difference in health outcomes based on blood levels of vitamin D would be much more meaningful. The participants were all given the same dose of D no matter how low their blood levels were to start with. Although researchers checked one year in and saw some increase that was not used as a factor in gauging results.
  • They did not check to see if participants had sufficient storage of magnesium to activate the vitamin D. By the conservative estimates, half of Amercians do not get enough magnesium.
  • I looked up the full text of the study to see if they monitored sun exposure and it appears they did not. This is important because, for all we know, the placebo group instinctively sought out more sun time. Milk contains vitamin D and it isn’t clear if they controlled for milk intake.
  • Although 5.3 years is long as studies go, cancer can take decades to reach diagnosis stage. Therefore, the benefit of vitamin D might be more apparent over a longer time. Interestingly, even in this brief time, there were already positive trends in every category. For example, this quote; “During follow-up, 341 participants died from cancer, with 154 such deaths in the vitamin D group and 187 in the placebo group.” That is a significant difference in my book, but it seems they were looking for invasive cancers, not deaths so this fact didn’t come out in the headlines.
  • In a discussion of other studies, this paper noted that different organs can have different needs for vitamin D. Also, those with a high body mass index (fat) need more D. Also, African Americans need 20% more vitamin D. This study included 20 % black participants. As is so often the case, all of these differences just mentioned were lumped together hiding what may be important to certain subgroups.
  • The study was not geared to record any fringe benefits participants might have enjoyed from increased D levels. E.g. they may have had fewer colds, a more cheerful outlook, more energy, etc.

Bottom line: Don’t take this study too seriously. The best thing to come out of it was showing no harmful side effects from a “high” dose of 2,000 IU. I recommend getting your blood levels tested and supplement with whatever dose it takes to stay in the optimum range.



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