Here are a couple of articles about D, how to get it, who gets it most, etc. Some good stats. They are both articles each just one in a series of article and both have lots of links and references. They mention a Boston University professor, but I'll have to look later and come back and edit my post as I got sidetracked and now don't have time. But, these two do seem like really good articles and the first one listed below mentions that the closer one lives to the equator the less likely one is to have other cancers (i.e. other than sun cancer), MS or other autoimmune diseases. Fascinating!
Vitamin Boost
From muscle strength to immunity, scientists find new vitamin D benefit
http://www.sciencenews.org/articles/20041009/bob8.asp
Understanding Vitamin D Deficiency
http://www.sciencenews.org/articles/20050430/food.asp
I realize this is kind of a tangent from the OP about taking CLO, but did seem to apply to the issue of not getting enough D from the sun depending on where you live.
I'll try to come back and add the info on the B.U. study later when I find it. HTH.
First edit:
The doctor from B.U. mentioned in the article above
is the one to whom I was referring. This article isn't the one I originally read, but is a
New York Times article that mentions his "prescription" of 20 percent of the amount of time it would take you to burn in the sun. He also mentions storing D from spring and summer exposure. And, taking a supplement, etc. Of course, in this article he mentions being a professor of dermatology, and by the time he wrote or was referenced in the article I read he'd been stripped of that professorship for advocating sun exposure.
A CONVERSATION WITH: MICHAEL HOLICK; Shining a Light on the Health Benefits of Vitamin D
http://query.nytimes.com/gst/fullpag...52C0A9659C8B63
Second Edit:
Second part of article "Vitamin Boost" above:
Vitamin D: What's Enough?
Many people may need much more
http://www.sciencenews.org/articles/20041016/bob9.asp
That's easy enough to do if you're, say, a white person working outdoors during the summer in New Jersey. In shorts and a T-shirt, such a person can soak up enough ultraviolet rays to produce 12,000 IU of vitamin D within 20 minutes, notes Reinhold Vieth of the University of Toronto.
The article discusses variability based on location, season, race.