Under the sun: Pendulum may be swinging toward less conservative view of vitamin D issue

June 1, 2008

The results of recent studies on the value of Vitamin D in warding off serious illnesses are fueling the ongoing debate over the dermatologic community's "official" stance that warns against the dangers of sunlight, from which the body most efficiently acquires Vitamin D.

Key Points

EDITOR'S NOTE: The summer sun is back ... and with it, the continuing debate over the health risks and benefits of exposure to its potentially damaging rays. In this issue, Dermatology Times looks at current studies into the protective effects of vitamin D. We also discuss a pro-tanning campaign by the Indoor Tanning Association; the latest developments in sunscreens; and efforts by the American Academy of Dermatology and the Women's Dermatological Society to boost public awareness about sun safety. This month's "On Call" also polls your colleagues about the FDA's proposed new sunscreen rules.

Over the past year, several studies have appeared suggesting that the benefits of vitamin D - manufactured by the body in response to sunlight - are more far-reaching than may previously have been thought.

"I do think that more dermatologists are seeing the value of limited, but not necessarily unprotected, sun exposure," says Washington, D.C., dermatologist Tina Alster, M.D. But while she believes there has been a slight shift in some of her colleagues' thinking on the issue, she agrees with the AAD's recommendations.

"Opening the door even a little to unprotected sun exposure increases people's risk of skin cancer," she says.

Recent studies are pointing to an ever-increasing range of potential health benefits from the "sunshine vitamin."

In February, the Journal of Clinical Endocrinology and Metabolism published a study showing that softening of the skull bones, or craniotabes, in newborns may be the result of vitamin D deficiency in the womb - and that, although it is usually regarded as no cause for concern, craniotabes is associated with type 1 diabetes, reduced bone mass in childhood and lowered immunity.

The study found that the highest rate of craniotabes occurred among infants born in April and May; the lowest, in those born in November.

The rate of craniotabes "was influenced by the daylight hours approximately four months prior to delivery," which in turn strongly suggests that "the condition is associated with vitamin D deficiency in utero," the researchers write.

They add that breast-fed infants with this condition may need vitamin D supplements, and that all pregnant women should take supplements if exposure to sunlight is limited.

Another study, published earlier this year in Archives of Disease in Childhood, suggests that children who take vitamin D supplements are less likely to develop type 1 diabetes later in life.

In analyzing the findings of five previously published studies, the researchers found that children who were given additional vitamin D are about 30 percent less likely to develop the disease than those who receive no supplement.

Noting that the incidence of type 1 diabetes is increasing by about 3 percent a year, the study also reports evidence that levels of vitamin D and exposure to sunlight influence the risk of developing some types of autoimmune disorders, and that global rates of type 1 diabetes vary greatly according to latitude and sunlight levels. A child in Finland, for example, is 400 times more likely to develop type 1 diabetes than a child in Venezuela.