Thursday, November 06, 2003

Soak up the sun: vitamin D and you

Dear Kari:

I'm gonna soak up the sun
I'm gonna tell everyone
To lighten up (on sunscreen)

No, Sheryl wasn't singing about vitamin D but she may be onto something.

One of the recent findings in the field of vitamin D research is that many of us may be vitamin D deficient.

What people may not know is that the first step in producing vitamin D in our bodies is a UV light dependent reaction in our skin. In the old days, when society was much more agriculture based, people were outside for many hours a day working the fields, or if one was a hunter, one would be running around outside chasing after supper. Today, with our information and service-based economy, we are inside almost all day long hence not getting much sunlight and because of fears of skin cancer we are all covered up and doused in sunscreen when we are outside.

The hints that something was amiss were reports of babies coming down with rickets (weak bones) as summarized in this article. This was notable in African American children which lead doctors to suspect that the mothers were vitamin D deficient thus the breast milk was deficient. The darker pigment of African Americans makes the first step of vitamin D production less efficient. Combine that with an indoor lifestyle and the reduced amount of sunshine living in northern latitude, you have the "perfect solar storm" in reverse.

Because of these findings, the American Academy of Pediatrics issued this policy statement on vitamin D supplementation for infants and children.

The other day, I heard a lecture by Bruce Hollis, a professor at the Medical University of South Carolina. He told us that the old standard for the bottom end of "normal" 25-hydroxyvitamin D (the form of vitamin D that is the best indicator of overall vitamin D status) in adults was 15 ng/L. It will now be upped to 30 ng/L. This new recommended level should resolve the rickets issues. However, he went on to suggest that that level might be still too low for other reasons.

Vitamin D remains a molecule of interest to medical researchers because of its potential anti-cancer effects. So far the data on that front remains unclear. However, some researchers are doing studies to see if vitamin D deficiency (not so low as to cause the obvious bone problems) might leave people more susceptible to cancers. Thus, 30 ng/L maybe fine to keep bone problems away but higher levels might actually be preferable.

Stay tuned over the next few years as these issues get sorted out.

In the meantime, take your supplements and Hollis suggested, allow yourself 10-15 minutes of sun before putting on the sunscreen.

I'm gonna soak up the sun
Got my (spf)45(not) on
So I can rock on

Be well,


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