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.
References
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.
