My dermatologist would have me wear sunscreen every day, slopping it on every two hours, even when I am indoors ("there's light coming from the lightbulbs"). She is a fanatic on the subject. I say, yes, yes, and then do as I please. (I do have a history of being a "difficult patient.") While she is right that I do need to be cautious, my skin is very fair and I have had numerous sunburns in the past, but I have grave reservations about blocking out sunlight to that extent. And I HATE sunscreen. I've tried all kinds and hate them all. I hate putting anything on my skin or in my hair for that matter. When I was young and there was no sunscreen, my mother would make me wear a shirt even when swimming. Yes, she tried.
Low-carbers are also sun-lovers. Vitamin D has become a hot topic and there have been several posts on this subject. It is lately becoming recognized as a very potent force for resisting infection and a deficiency is implicated in a host of other diseases including all kinds of cancers. The BEST way to get your Vitamin D is from sun exposure. They say you can overdose by taking supplements, although it is hard to do, so if you decide to go that route, you need to have your vitamin D levels checked every so often. The 25-hydroxyvitamin D test is the test that is recommended. But you cannot overdose when getting your D from the sun.
Since research into this hormone (technically it's not a vitamin) is very recent, they are still tweaking their advice on how to safely do this. They used to say that you should go out early or late in the day and avoid the hottest parts of the day. That made sense to me. It's what I would think primal man did; only a lunatic goes out in the noonday sun. But now they are saying, and even my dermatologist agrees with this, that it is the UV-A that causes cancer while it is the UV-B that makes vitamin D and causes sunburn. UV-A is stronger in the early and late hours of the day, as well as when it is overcast, because the clouds filter out the UV-B. It seems that the function of UV-A is to prevent us from getting too much vitamin D. It turns off vitamin D production. So now they have switched their recommendation to saying you should go out when the sun is high and expose as much skin as possible to the sun's rays until you get the faintest pink blush. For me, 10 minutes does it.
In his book, Sugar Blues, William Dufty states that if you eliminate sugar from your diet after awhile you will be able to tolerate more sun exposure without burning. I have read a few comments to various blogs where the person said that this was true for them. It hasn't happened for me, yet. I still burn very easily.
Dr. Michael Holick, professor at Boston University, was one of the early researchers into the benefits of vitamin D. I used to own his book, The UV Advantage, but I tossed it out when trying to reduce my "stuff" a few years ago. Now I wish I had kept it. But Dr. Holick is coming out with a new book next spring, The Vitamin D Solution, which I will surely buy. Here is a link to a symposium talk that Dr. Holick gave in 2007 that is very entertaining and very informative. It is rather long and gets technical at the end, but it is well worth the time spent to view it. Another very good source of information is Dr. John Cannell's Vitamin D Council website.
What to do? Well, it's summer. Getting enough sun exposure is fairly easy for me at this time of year. I toast myself 10 minutes on a side at, or close to, high noon, using a timer for precision (I don't see the blush until later, when it's too late). If I am out longer than that, on goes a hat, a light long-sleeved shirt, and (sigh!) sunscreen. BTW: I got a sunscreen from my dermatologist that protects better than most against UV-A radiation as well as UV-B. I have taken supplements in the past and may do so again next winter. And I plan to get my vitamin D levels checked.