[Lowell: another personal blog post from August, 2009. You’ll be happy to hear my 25(OH)-D levels were fixed up very quickly after this, and now they’re easily over 60-70 all the time]
Free the Animal linked to a blog I hadn’t read before called Primal Wisdom. It looks pretty good so far, and for now I’ve added it to the 9 other health-related blogs I follow on a daily basis. The author is a philosophy major, nutritionist, sports trainer, and has studied oriental medicine as well. He’s currently the head of the nutrition department at a school in Arizona. In addition to just sharing the link to the blog in general, I ran across the following post that (amongst the many others out there on the topic) does a great job of providing a very short but good intro to how UVB light and Vitamin D3 are incredibly important, and very few people get enough of them anymore:
I’ve read tons on UVB and UVA, melanoma, sunlight, vitamin D3 (and D2), and the many connections of D3 levels to tons of health measures and conditions. It isn’t too surprising we evolved to take advantage of the energy from the sun; the body loads D2 into the skin, where UVB rays oxidize it to D3, when it is then absorbed back and shipped around the body to do all kinds of useful things. One of the better semi-comprehensive Vitamin D posts is (from PaNu):
The big surprise for me has been that my personal D levels are still pretty low. The lab test to measure the amount of D3 (the happy active form for us humans) you have is a 25(OH)D test (there are several tests, and the others don’t measure the right thing to determine if you’re getting enough sunlight and/or D3 supplements). My 25(OH)D level, tested just this month, was only ~32. It was ~30 several months ago. In that time I’ve worked hard to increase my sun and UVB exposure, and still I only increased my level by 2. Below 40 indicates weaker bones, and you have to get over 50 to be in a good optimal range. Anyhow, I’m adding some additional D3 supplements (to make up for the northern latitude here in Seattle) and am continuing to try and get lots of sunlight (or at least sun-equivalent light with a good ratio of UVB to UVA).
Anyhow, I pretty much agree with most of the good sources who have written about this already. The best source is natural sunlight, and midday sunlight is the only way to get adequate Vitamin D3. If you’re only outside in the morning and afternoon, you’re getting too much UVA and not enough UVB. But, of course, most of our schedules don’t permit this. So it comes down to finding replacement sources—normally I’m actually not much for supplements, but when there’s a valid argument that the supplement is really just replacing something you should have gotten with a normal human (read: primal) lifestyle, I’m all for it. So D3 (not D2) supplements are a reasonable approach. Of course, the delivery mechanism is different than UVB on the skin, so I think trying to get your D3 via UVB light (natural preferred, artificial as a backup) is a better approach than supplements on the whole.