A couple of things to bear in mind. Ultraviolet (UV) radiation is a known carcinogen that is responsible for photoaging [it makes you look older] and for well over 1 million skin cancers each year in the U.S. At current rates, one in five Americans will develop skin cancer during their lifetimes. It is estimated that 10,500 people lost their lives to skin cancer last year.

In an article I read recently, Dermatologist Barbara A. Gilchrest, M.D., professor and chair of the department of dermatology at Boston University School of Medicine, advised the public to turn to vitamin D fortified foods and nutritional supplements instead of unprotected sun exposure to assure adequate levels of the vitamin. Even in winter months when very little to no vitamin D can be made from sunlight, her review of the existing scientific literature found that diet and daily vitamin D supplements were all that was needed to maintain adequate amounts of the nutrient.

As reported in Newsweek and the Women's Cancer Network, researchers are recommending taking vitamin D supplements to ward off certain cancers, the recommeded dosage being 1,000 IU of vitamin D3 per day [this is considerably above the RDA]. Supposedly supplementing in this way may lower an individual's risk of getting breast, colon, prostate, and ovarian cancer by up to 50%. As a former skin-cancer patient (melanoma), I happen to take 1,400 IU. [2,000 IU is the upper limit for safety, though some say much higher levels are safe.]

If you take vitamin D supplements, make sure it is vitamin D3 that you are getting.

From what I gather from what I have read, there is no added risk of getting too much vitamin D by taking supplements and then getting sun exposure. If that is true, it must be that the body adjusts in some way, or does not absorb the additional vitamin D.