D is for 'debate'

June 1, 2007

The sunshine and vitamin D debate rages on, with doctors disagreeing on how much vitamin D people should have on a daily basis - and on how that vitamin D is obtained - through supplements or sunlight.

Key Points

National report - In the dermatologic community, the "D" in vitamin D could well stand for "debate."

Exposure to sunlight is the body's most efficient way of generating vitamin D. But sunlight is a known carcinogen, and the incidence of skin cancers - particularly the potentially deadly malignant melanoma - is on the rise, according to public health statistics.

So where is the balance? How much sun is too much? What should dermatologists tell their patients to help them minimize the risk of skin cancer while maintaining sufficient levels of vitamin D to protect themselves against other diseases?

He and other doctors believe sufficient levels of vitamin D can be maintained through dietary sources and supplements.

"Unless patients live in fairly desperate northern climes," Dr. Schlessinger tells Dermatology Times, "enough vitamin D is taken in via dietary and solar exposure in everyday living.

"As far as how much exposure is too much, and how much is not enough, there's a very fine balance," he says. "But in my opinion, it's fairly lopsided in favor of minimal sun exposure."

Melanoma on the rise

According to the American Academy of Dermatology's most recent statistics, the incidence of melanoma rose nearly 700 percent between 1950 and 2001, and the overall mortality rate increased 165 percent during the same period.

But some recent research, ironically, suggests that vitamin D may well help prevent skin cancer as well as other diseases. A 2005 study by Edward Giovannucci, M.D., a Harvard University professor of medicine and nutrition, suggests that vitamin D might help prevent 30 deaths for each one caused by skin cancer (J Natl Cancer Inst. 2006 Apr 5;98[7]:428-430).

A more recent study by investigators at Stanford University similarly suggests that vitamin D generated by the sun's rays helps protect the skin against cellular damage - including that caused by sunlight itself (Nat Immunol. 2007 Mar;8[3]:285-293. Epub 2007 Jan 28).

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