The feel of the warm sun on bare skin that has been covered by clothing during the winter is an experience Americans have come to love...all too much, say dermatologists.
Ultraviolet (UV) radiation has been linked to skin cancer, premature aging of the skin and an increased risk of cataracts. Excessive sun exposure and sunburns during youth may increase the risk of melanoma, the most serious skin cancer. And tanning may be even more dangerous, provoking a response designed to protect the DNA of cells.
To protect yourself from skin cancer, dermatologists recommend daily use of sunscreen, even for short-term exposure such as walking to your car in a parking lot or sitting at an outside table for lunch.
But there is another side to the story. Vitamin D is an important hormone that is manufactured by the body only when the skin is exposed to ultraviolet rays.
Studies have long shown that prostate cancer deaths are highest in areas where exposure to UV rays is the lowest–with nearly twice as many deaths in Maine as in Florida. Death rates from breast and ovarian cancer are also twice as high in northern states as in sunny ones. Recent studies confirm that vitamin D deficiency is a significant risk factor for these and other cancers, including colorectal cancer and non-Hodgkin’s lymphoma.
Vitamin D has many other health benefits, lowering the risk of cardiovascular disease and osteoporosis in 10,000 older women enrolled in the ongoing Study of Osteoporotic Fractures. Without vitamin D the body cannot properly absorb and utilize the calcium and phosphorus needed to build and maintain strong bones.
Older adults with poor diets who don’t get outside often are at risk of bone fractures and osteoporosis as well as cancer and heart disease. Rickets, a severe vitamin-D deficiency believed to have been eliminated when children were removed from windowless sweat shops, is making a comeback. A recent study found that 24 percent of adolescents in the Boston area, including a large number of African Americans, were deficient in vitamin D.
Vitamin D in the diet is obtained largely from eggs and oily fish such as salmon and mackerel. Milk is supposed to contain 400 IU of vitamin D per quart, but studies have found that it rarely has as much as stated and that many samples of skim milk have no vitamin D.
Sunshine is a convenient and inexpensive way to obtain vitamin D, but persons living above 40 degrees north latitude do not get enough sunlight in winter to make vitamin D. As to whether wearing sunscreen with an SPF of 15 or higher–as most dermatologists recommend–blocks vitamin D production, research has produced conflicting results and even conflicting interpretations of the same results.
What’s important is that adolescents and young adults who might otherwise bake their bodies to a crisp on the beach or in a tanning salon understand the danger and start using sunscreen.
Persons living in northern areas with little access to the sun in winter months should recognize the importance of getting sufficient vitamin D–from food, supplements and, perhaps, from casual exposure to sunlight. In addition, there are some individuals with special needs for vitamin D:
- older women and men who are at risk of osteoporosis,
- dark-skinned African Americans,
- pregnant women,
- and anyone with an elevated risk of prostate, breast, ovarian or colorectal cancer.
Individuals with a history of depression should not shun sunlight. For seasonal depression, however, it is the visible rather than ultraviolet rays of sun that are beneficial.
The sun is a powerful, life-giving force. Respect it for its benefits as well as its risks. For more information about sun exposure, talk to your doctor, or call St. John’s Referral One at (417) 625-2000.
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