One of the controversies surrounding sun exposure that has cropped up over the past few years is the issue of vitamin D deficiency. Sunlight is the primary source of vitamin D, and vitamin D deficiencies can be a serious health problem. As luck would have it, sunlight is the most abundant, natural source that helps our bodies make vitamin D. Lack of sun exposure and the resulting vitamin D deficiency it can cause has been linked to many serious chronic diseases, including autoimmune diseases, bone loss, infectious diseases, cardiovascular disease, and cancers. It is estimated that a 30% to 50% reduction in risk for developing colorectal, breast, and prostate cancer is possible by either increasing vitamin D intake to at least 1000 IU per day, or increasing sun exposure.

Despite the name, vitamin D is not actually a vitamin. It is a hormone known as calcitrol. When your skin is exposed to UVB light, it converts 7-dehydrocholesterol (present in your skin and bloodstream) into vitamin D, where the liver and kidneys activate it and it begins regulating and enhancing the absorption of the minerals calcium and phosphorus in the body. Since there are very few foods that naturally contain vitamin D—your best options are salmon, mackerel, and cod liver oil—most of us need to rely either on sun exposure or vitamin D–fortified foods such as milk and cereals (which is unrealistic because you could never eat enough of the stuff on a daily basis to get the amount you need), or vitamin D supplements to ensure we get enough.

What type of vitamin D supplement should you take? There are two forms that are considered important to the body: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). Although both were considered equally effective for decades, recent research has proven that cholecalciferol is the more potent (thus effective) form. Vitamin D3 has proven to be more efficient at raising the body’s levels of vitamin D, as measurable by blood testing.

Does that mean you have to choose between sun exposure and taking vitamin D supplements? Many advocates want you to get sun exposure so your body produces the vitamin D naturally, while others encourage vitamin D supplements so you avoid the skin-cancer risk caused by unprotected sun exposure.

From the skin’s perspective the choice seems easy: Vitamin D supplements and protecting your skin from sun damage are the smart choices. The body can’t tell whether it’s vitamin D supplements that are providing what you need, or whether it’s produced in the body from sun exposure. Rather than choosing between a rock and a hard place (that is, skin cancer, wrinkles, and skin discolorations on one hand, or the serious health problems associated with vitamin D deficiency), it makes the most sense to choose to take the balanced approach and do two healthy things at the same time.

(Sources for the above information: Nutrition Review, October 2008, pages S182–S194; Pigment Cell and Melanoma Research, October 2008, pages 509–516; Clinical Journal of the American Society of Nephrology; September 2008, pages 1548–1554; Photochemistry and Photobiological Science, March 2007, pages 232–251; Progress in Biophysics and Molecular Biology, September 2006, pages 9–16; Journal of the American Academy of Dermatology, December 1997, pages 942–947; and www.naturaldatabase.com .)

Some people worry that if they use sunscreen it will cancel out their body’s ability to absorb vitamin D from the sun. Here, the controversy is between those who feel that exposing our skin to the sun without sunscreen is dangerous, versus those who believe that sunscreen will cancel out the body’s ability to manufacture vitamin D from sun exposure. This concern over sunscreen has been expressed in the pages of several reputable resources. (Sources: em>Photochemistry and Photobiology, March-April 2007, pages 459–463; American Journal of Clinical Nutrition, December 2004, pages S1678–1688S; and Archives of Dermatology, December 1988, pages 1802–1804.)

There are mixed opinions on this one (I know, it’s always complicated). Regarding this issue, a June 1999 article in Cosmetic Dermatology (page 43) discussed a presentation given by Mark Naylor, MD, assistant professor in the Department of Dermatology at the University of Oklahoma, which described some research on use of sunscreen: “Prospective sunscreen trials examining whether sunscreen contributes to vitamin D deficiency found that regular sunscreen users were not vitamin D deficient.” Other research has echoed that assertion. (Source: Journal of Photochemistry and Photobiology, December 2007, pages 139–147.)

There is also the issue that no sunscreen, regardless of its active ingredients or how often or liberally it is applied, can provide 100% protection from UV radiation. The tiny amount of UVB light that sunscreens do not shield us from is enough to begin the synthesis of vitamin D, although—depending on your skin color, environment (how much daily sunshine is there), and climate—supplemental vitamin D will likely still be necessary.

There is no question that we need vitamin D, either from the sun or supplementation, because research has found a large percentage of the population is deficient in vitamin D, especially as we age. If skin wrinkles, premature aging of the skin, and skin cancers are an issue for you, then the answer is clear: you need to do both—diligently protect your skin from the sun and take a vitamin D supplement.

(Additional sources for the above: The Journal of the American Osteopathic Association, August 2003, pages 3–4; American Journal of Clinical Dermatology, March 2002, pages 185–191; Dermatology, January 2001, pages 27–30; British Medical Journal, October 1999, page 1066; Archives of Dermatology, April 1005, pages 415–421).

Note: Before beginning any new vitamin supplement program, make sure to consult your physician.