Use of sunscreens does not risk vitamin D deficiency

EDITOR—Ness et al misinterpret our work in Australia by stating that we showed that use of sunscreens reduced vitamin D concentrations.1 In fact, we showed that the use of sunscreens did not prevent the normal summer rise in 25-hydroxy vitamin D concentration (the vitamin D fraction that is used to assess vitamin D deficiency).2 Subjects using sunscreens compared with controls using a placebo cream had an equal rise over the summer.

As an extension of the study we also measured concentrations of 1, 25-hydroxy vitamin D. This fraction of vitamin D is believed to be regulated by 25-hydroxy vitamin D concentrations via a negative feedback mechanism. We found a rise in 1, 25-hydroxy vitamin D concentrations over the summer in people using sunscreen, but the rise was smaller than that among those using placebo. In a small group there was a lower, but not significantly different, concentration of 1, 25-hydroxy vitamin D at the end of summer. However, this occurred in the presence of a substantial rise in 25-hydroxy vitamin D concentrations (the vitamin D fraction that controls 1, 25-hydroxy vitamin D) in all subjects. We also made it clear in our paper that the 1, 25-hydroxy vitamin D concentrations of all the participants in the placebo and sunscreen groups remained within the normal range all the way through the study.

It is mischievous and specious to imply that our work was suggesting that use of sunscreen might lead to vitamin D deficiency. We made the opposite point very strongly in the paper and clearly explained why, in the presence of raised 25-hydroxy vitamin D concentrations, the slightly smaller changes in 1, 25-hydroxy vitamin D could not be interpreted as a risk for vitamin D deficiency.

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