Over the past decade or so, there’s been a real avalanche of research on vitamin D.

vitamin D3Just last week, word came of two new studies – one suggesting the nutrient could play a role in pain management; the other, that supplementation could help improve fertility in both men and women. A little earlier this year, research in JAMA suggested that higher D levels may lower risk for some cancers.

Combine findings like these with the fact that most Americans have suboptimal D levels, and you get a loud choir of practitioners insisting that their patients supplement.

The usual recommendation is that you take D3. D3 is the form we get mainly from the sun, as well as a few animal foods, and it’s the form most beneficial to human health. Many rightly recommend that it be taken along with vitamin K2, since your body can’t really use the D without it.

But some naturopathic physicians are starting to question the conventional holistic wisdom.

In a recent article for the Natural Medicine Journal, naturopathic oncologist Dr. Jacob Schor notes that several major, recent reviews of the literature have found the evidence for supplemental D to be lacking – at least for the conditions studied (fractures; skeletal, vascular, and cancer outcomes; fall prevention).

Maybe, he said, it’s not the vitamin D itself that’s crucial but the way we get it in nature: exposure to sunlight.

Sunlight has a range of actions on the human body, only some of which we understand. Besides triggering vitamin D production it also triggers production of p53,4 the enzyme that regulates apoptosis (cell suicide) and destroys cancer cells, or at least is supposed to. Increasing p53 activity is the primary goal of both conventional and naturopathic oncologists. This may be why sun exposure is associated with decreased cancer risk.

Sunlight also triggers nitric oxide (NO) production, which in turn causes vasodilation, lowering blood pressure. NO may be why sunlight lowers risk of heart disease and strokes.

Perhaps it’s not the D but the sun that is protective. As high blood pressure is the leading cause of death in the world, even small improvements in blood pressure might have widespread consequences. This NO discovery explains a long-time mystery, why blood pressures are higher during the winter. It also explains why blood pressures increase with latitude.

A December 2016 article in the journal Medical Hypotheses, suggests several other possible explanations for the benefits of sunlight including immunomodulation, melatonin, serotonin, and the effect on circadian clocks, which are also involved in triggering the health benefits of sunlight. A paper published in late January 2017 reported that sun exposure stimulates lymphocyte motility and gets those white blood cells to chase down invading microbes in the body. Perhaps this is why sun exposure reduces rates of infection?

It’s a compelling possibility, to be sure.

Regardless, we can say that just as the ideal way to get the nutrients you need is through real, whole food, so, too, the ideal is to get your D the way nature intended: from sunlight.

sunshineMost of us need just 10 to 15 minutes of daily sun exposure to maintain adequate D levels – though this can vary depending on where you live and your skin pigmentation. There’s a handy online tool that will factor in all the variables you enter and calculate the amount of sun time you, specifically, need.

One thing to keep in mind, though, is that it’s the ultraviolet radiation in sunlight that helps your body synthesize D. Sunblock can defeat the purpose. Fortunately, the exposure time you need is quite short. If you’ll be out in the sun for prolonged periods, however, you do want to protect your skin. (Check out EWG’s guide to sunscreens, as well as their sun safety tips.)

If you’re very fair skinned and must use sunblock, look first to eating more D-rich foods – you’ll find a list of them here – and then supplementing as needed.

D3 image by Sbrools, via Wikimedia Commons


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