Getting Your Vitamin D from Sun Exposure: Weighing the Risks and Benefits
Long known as an important factor in bone health, a quickly growing body of evidence now also shows that vitamin D may help lower the risk of cancer, heart disease, and even premature death.1,2 Sun exposure, in addition to dietary sources, is one way to obtain vitamin D; however, with concerns about skin-cancer risk, it’s difficult to determine whether the benefits of boosting your vitamin D in this way outweigh the risks.
Often referred to as the “sunshine vitamin” because direct exposure to ultraviolet B (UV-B) sunlight causes the vitamin to naturally form in the skin, the issue of whether or not to encourage people to spend a little time in the sun to reap the benefits of vitamin D production is a bit of double-edged sword for the public health community. While sun is in fact a potent (and free) source of vitamin D—producing all you’d need in a day in about 10 minutes of unprotected exposure, depending on where you live—it’s also a clear cause of skin cancer, including deadly melanoma. “Safe sun” proponents feel that the benefits of a small amount of sun exposure could far outweigh the risks. And the numbers can make the point compelling. About 8,500 people die of melanoma every year, whereas increased vitamin D levels, partially boosted by sun exposure, could possibly prevent over 50,000 cancer deaths overall annually.
Still, it’s hard to find the right balance of risk and benefits, especially when vitamin D supplements are easy to come by and relatively cheap. Is it okay to promote something that causes melanoma, when there’s a safer alternative that has the same benefits? For now, most experts lean toward boosting vitamin D levels with pills rather than sun. But, the discussion continues, and newer data may help provide some clarity in the future on the “safe sun” issue.
1.Heaney RP. Vitamin D in health and disease. Clin J Am Soc Nephrol. Sep 2008;3(5):1535-1541.
2.Melamed ML, Michos ED, Post W, Astor B. 25-hydroxyvitamin D levels and the risk of mortality in the general population. Arch Intern Med. Aug 11 2008;168(15):1629-1637.