Diet Less Risky Source
Of Vitamin D Than Sun
NEW YORK (Reuters Health) - The amount of vitamin D in the typical Western diet is sufficient, so sun exposure is usually not necessary to ensure adequate levels of the vitamin, according to research presented at the recent American Academy of Dermatology (AAD) conference on skin cancer prevention.
Individuals seeking to supplement their levels of vitamin D, which preliminary research suggests may prevent some cancers, need not " and should not " expose themselves to the sun's ultraviolet (UV) rays to do it, according to Dr. Mark Naylor of the University of Oklahoma in Oklahoma City.
Sunlight triggers vitamin D production in the skin. But sun exposure is also a known risk factor for skin cancers.
"The dangers of UV exposure " such as chromosome damage, DNA mutation, and immune system suppression " should be the guiding principle that governs our recommendations to the public, particularly since dietary intake of vitamin D can completely and easily fulfill our needs,'' Naylor said.
The safe, cheap, and effective oral forms of vitamin D available " in fish, meat products, multivitamins and supplemented in dairy products and in commercially baked goods " "make it very difficult for me to argue that we should ever recommend that people expose themselves to a carcinogen like sunlight in order to get (vitamin D),'' said Naylor at the conference.
Naylor also said that "the value of vitamin D supplementation in preventing cancer is completely unproven, although there is some theoretical research indicating it might work.''
Recent studies that linked UV exposure to a decrease in cancers including breast and colon cancers were extremely inconclusive, pointed out Naylor, adding that speculative theories arising from such studies threaten individuals gullible enough to forego wearing sunscreen in the hopes of lowering their cancer risk.
"If someone asked you to participate in a study that would maybe reduce your risk of colon, prostate and breast cancer,'' many would respond "'that sounds great, where do I sign up?','' he said.
"But the problem is, this caveat,'' continued Naylor. "The drug vehicle is a known carcinogen that increases your risk of other... forms of cancer, of skin cancer, and reduces immunosuppression. So are you ready to sign up for that study? I'm not.''
While the number of new cases for most cancers declined from 1990 to 1996, rates of the skin cancer melanoma continued to rise, approximately 3% annually, according to a report in the Journal of the National Cancer Institute cited by an AAD press statement.