Extra vitamin D intake favored over sun exposure.(Clinical Rounds)

SAN FRANCISCO -- The burning issue of how best to make sure that patients get enough vitamin D comes down to this conclusion: Recommending intentional exposure to the sun's rays is inappropriate, Dr. Henry W. Lim said.

Instead, for patients at risk of vitamin D deficiency recommend a vitamin D-fortified diet and daily supplements of 800 IU of vitamin D (ideally vitamin [D.sub.3]) plus calcium, he said at the annual meeting of the American Academy of Dermatology.

Dr. Lim, chairman of the dermatology residency program at Henry Ford Hospital, Detroit, organized the academy's 2005 consensus conference titled "Sunlight, Tanning Booths, and Vitamin D." At the annual meeting he discussed more recent data on vitamin D and presented his preferred approach to vitamin D management.

Intentional sun exposure is a problem because the harmful side effects of UVB can't be separated from the beneficial vitamin D photosynthesis that sunlight provides. UV light acutely damages skin DNA and can cause erythema, sunburn, and photoimmunosuppression. In the long term, UV irradiation leads to photoaging and possible photocarcinogenesis. Half of all cancers in humans are skin cancers.

In addition, vitamin D synthesis appears to occur at different rates in people of different skin types. That plus significant daily and seasonal variability in weather patterns and available sunlight make it difficult to craft public health policies based on intentional sun exposure, Dr. Lim said.

Studies have identified certain populations that may not be getting adequate vitamin D, including the elderly, people with darkly pigmented skin, and those living in wintry climates. Other studies, however, show that most people achieve adequate vitamin D serum levels in the course of normal daily life, even when using sunscreen, presumably through incidental sun exposure, dietary intake, and supplementation, he added.

Recent data suggest that levels in U.S. whites averaged 80 nmol/L, "which is considered nowadays by most studies to be an adequate level of serum vitamin D," Dr. Lim noted. In Hispanic Americans, however, serum levels averaged 60 nmol/L, and in U.S. blacks, serum vitamin D averaged ...