Sunscreen does lower vitamin D, but only by about 2 ng/mL

Sunscreen exists to block ultraviolet radiation, and UV-B is precisely the wavelength the skin uses to manufacture vitamin D3. That overlap has fuelled a long-running worry that diligent sunscreen use might quietly drive vitamin D levels down. The literature has disagreed for years: laboratory experiments show sunscreen clearly blocks the relevant radiation, while studies of actual people have gone both ways. This review set out to establish what sunscreen use really does to circulating 25-hydroxyvitamin D, the standard blood marker of vitamin D status.

The authors searched PubMed/MEDLINE, Scopus and Web of Science from inception to November 2024 for studies comparing 25-hydroxyvitamin D levels in people who did or did not apply sunscreen during sun exposure. Twenty-two studies made it into the overall synthesis and 7 provided data suitable for statistical pooling, together covering 9470 participants. Study quality and risk of bias were formally assessed, and the review followed standard PRISMA reporting guidance for systematic evidence summaries.

Pooled across studies, sunscreen use was associated with lower vitamin D: a reduction of around 2 ng/mL in serum 25-hydroxyvitamin D, with the plausible range running between 1 and 3 ng/mL lower. The pooled studies agreed with each other reasonably well, which strengthens confidence in the direction of the effect. The wider literature told a more textured story: laboratory studies consistently showed sunscreen blocks the UV-B radiation needed for vitamin D3 production, while population studies were mixed, with lower levels most apparent in people who already had limited sun exposure.

This pooling brings some order to a genuinely conflicted literature, confirming the mechanistic expectation that sunscreen reduces vitamin D synthesis while sizing the real-world effect as modest. It complicates both camps: those who dismissed the effect entirely, and those who warned that sunscreen was a major driver of deficiency. The open question the authors flag is whether a reduction of this size carries any meaningful health consequence, and how circumstances such as limited sun exposure change the picture. They call for further research before the finding should shape public health recommendations.

If you wear sunscreen regularly, it is reasonable to assume your vitamin D levels run slightly lower than they otherwise would, with the pooled estimate putting the difference at about 2 ng/mL. Nothing in this review shows that gap translates into a health problem, and the effect looked most relevant for people who get little sun in the first place. This is context, not a verdict against sun protection; the authors themselves say the broader health implications still need to be determined.