Tanning and vitamin D status

VA Medical Center Providence
Department of Dermatology and Community Health
Brown University
Providence, RI 02912

Division of Epidemiology and Community Health
University of Minnesota
Minneapolis, MN
E-mail: maw{at}brown.edu

Dear Sir:

We read with concern the article by Tangpricha et al (1) on tanning and vitamin D status in a recent issue of the Journal. They concluded, on the basis of their study, that "tanning beds may also provide some medical benefit." Our concern is based on several factors.

First, Tangpricha et al recruited a convenience sample via an online bulletin board and newspaper advertisement. Hence, their study population was likely not representative of the general population. As a consequence, their results could be biased by the self-selected nature of their study participants. Furthermore, their comparison of vitamin D concentrations in tanners and nontanners may have been biased by their failure to account for differences in ethnic group, multivitamin consumption, or sunlight exposure between the 2 groups—factors that may have led to spuriously low vitamin D concentrations in nontanners relative to tanners.

Second, patrons of commercial tanning parlors are unable to distinguish whether the lamps to which they are exposed emit pure ultraviolet (UV) A radiation (ie, wavelengths between 320 and 400 nm), which will not result in the photosynthesis of vitamin D in human skin, or emit a mixture of UV B (ie, wavelengths between 280 and 320 nm) and UVA radiation, which will result in the photosynthesis of vitamin D in human skin, nor can they tell how much UVB radiation is emitted by these lamps.

Third, the investigators imply that artificial tanning lamps may be useful for improving vitamin D status, but they downplay their carcinogenicity. Artificial tanning has been linked to multiple types of skin cancers. Oral vitamin supplements are a safer, much less expensive, and more convenient method for improving vitamin D status.

Fourth, the authors of the article acknowledge having received support from the UV Foundation for their work, and the senior author is a consultant for this foundation. However, the authors failed to note the close connection between the UV Foundation and the commercial tanning industry. Were the readers aware of this close connection, they might infer that the implicit endorsement of tanning parlors in this article is related to the authors' financial connections with the commercial tanning industry.

ACKNOWLEDGMENTS

MAW is a member of the American Academy of Dermatology, which has supported more rigorous controls on tanning parlors. Neither MAW nor DL had a conflict of interest to declare.

REFERENCE

1. Tangpricha V, Turner A, Spina C, Decastro S, Chen TC, Holick MF. Tanning is associated with optimal vitamin D status (serum 25-hydroxyvitamin D concentration) and higher bone mineral density. Am J Clin Nutr 2004;80:1645–9.