Sunlight: Good or Bad for Cancer Risk?
Brief Sun Exposure Produces Vitamin D, May Protect Against Non-Skin Cancer Deaths
Sun, Vitamin D, and Cancer
The researchers "took information that was known and looked at it in a different way," says Cedric Garland, DPH, professor of family & preventive medicine at the University of California, San Diego, who has also researched the association between Vitamin D, the sun, and cancer risk.
The new paper, he adds, "draws attention to existing studies that have shown that vitamin D deficiency is a cause of cancers of the breast, colon, prostate, ovary, pancreas, and kidney.''
Advice on Sun and Vitamin D
Getting brief, unprotected sun exposure might be wise, especially for those over age 60, Setlow says, who are more likely than younger people to be vitamin D-deficient. The chance of brief sun exposure causing deadly skin cancer, which generally takes years to develop, is less likely at that age, he says.
Garland's recommendation: Increase your intake of vitamin D, especially if you think you might be deficient. He recommends 1,000 to 2,000 international units (IU) a day plus 10 or 15 minutes of exposure to the sun within an hour of noon on clear days, with 40% of your skin exposed. Getting a doctor's approval first is wise.
Those two strategies, he says, "will bring the blood level of vitamin D up to what is considered protective."
Skin Cancer Foundation Disagrees
Exposure to unprotected sun is not a good idea, according to the Skin Cancer Foundation.
"While some population studies suggest that vitamin D levels, such as those that could result from sun exposure, may be beneficial for cancer survival, current scientific data suggest that proper sun protection remains a key element of a skin cancer protection program," says David J. Leffell, MD, vice president of the Skin Cancer Foundation and director of the Yale Medical Group in New Haven, Conn.
Until more is known, he says, dermatologists recommend using sunscreen and other sun precautions and getting vitamin D from foods and supplements.
The adequate intake of vitamin D as set by the Institute of Medicine is 200 IUs for those aged 19 to 50, 400 IUs for those 51 to 70, and 600 IUs for those over age 71. The safe upper limit is 2,000 IUs for those over age 19. Sources of vitamin D from food include salmon, mackerel, and vitamin D-fortified milk and cereal.