eating · health

Vitamin D: What’s a reasonable person to do?


I often blog about topics where I’ve done some research and thought I’d save you the time. On topics such as exercise non-responders (Or, are you a non responder?), intermittent fasting and women’s health (Intermittent fasting and why it might not work), and athletes and pain tolerance (Are athletes masochists?) I’m far from an expert in the field but I’ve read enough to have some conclusions to share.

But on some topics, I’m perplexed. I’ve read a fair bit but I’m still not sure what to think or do about Vitamin D.  Let’s start with the question that many of us in the northern hemisphere worry about, are you getting enough Vitamin D?


But it’s not clear that supplements help. See the Limits of Vitamin D Supplements.





“Unfortunately, there is probably no benefit to expect from vitamin D supplementation in normally healthy people,” he said.

See also, from Precision Nutrition, Vitamin D supplements: Are yours helping or hurting you?

Almost every expert recommends it. And everyone’s taking it. But what if we’ve been using it wrong? What if our vitamin D supplements aren’t really helping us at all?
If your car’s oil light went on once a week…and every time you checked the oil, it was running low…what would you do?
Shrug? Top up the oil tank (again)? Do your best to forget about it?
Or would you try to figure out the cause? Why that oil light kept coming on? Why your oil was running low?
If you’re smart, you take your car to the mechanic. Where you learn that low oil is just a symptom. There, the mechanic looks for the real problem.
Why, then, don’t we take the same approach with our health? With our supplements?
Why’s that vitamin D low?
Research over the last few years has indicated that a large percent of the world’s population is low in vitamin D. However, the response to this is kinda strange.
Healthcare practitioners typically test a patient’s vitamin D levels and notice that they’re low.
Then s/he prescribes a vitamin D supplement.
The patient comes in again a few months later and vitamin D is still low.
So the doctor increases the supplement.
Interestingly, very few professionals ever ask: Why is this person’s “vitamin D tank” leaking in the first place?

In case you thought indoor tanning in the winter was a reasonable response, think again. The Canadian Cancer Society says, “Using tanning beds may increase vitamin D production, depending on the type of bulbs used (only UVB radiation can stimulate vitamin D production). But tanning beds are not a safe way to get vitamin D. There are safer ways to get vitamin D.”  Read more:

The International Skin Cancer Foundation puts in in stronger terms.




But should we test everyone for vitamin D deficiency?

There are problems with making vitamin D tests a standard part of preventive medicine, a federal panel said. The U.S. Preventive Services Task Force said Monday there’s not enough evidence of benefits or harms to recommend vitamin D testing for all. And even though some studies have associated low levels of vitamin D with a long list of ills, including a higher risk of fractures, falls, heart disease, colorectal cancer, diabetes, depression, thinking problems and death, scientists who evaluated studies for the USPSTF say there is no direct evidence that universal screening would reduce those risks. “The effect of vitamin D levels on health outcomes is difficult to evaluate,” the recommendation statement says.

So what do I do for now? I get outside in the sun when it appears. Walking my dog helps. And I do take a Vitamin D pill in the lowest sun months. Given the above I’m not sure it’s doing me any good but it’s a low enough dose that it’s not doing me any harm either.

What do you do about Vitamin D in the winter? Why? (And although I’m a professor and this is exam season, I don’t mean that question in an exam like way! I’m curious about what decisions others make when it’s not clear what the facts are.)