An interesting question and one that is of great concern these days as we learn more and more about how important vitamin D levels are in the development of various diseases—cancer being the most concerning. While sunscreen can reduce the sun’s adverse effects, there are concerns that it might inhibit the body’s production of vitamin D. Now, investigators at King’s College London have published new data that sheds new light on whether sunscreen compromises levels of vitamin D produced by the human body.

“Sunlight is the main source of vitamin D. Sunscreens can prevent sunburn and skin cancer, but there has been a lot of uncertainty about the effects of sunscreens on vitamin D,” said lead study investigator Antony Young, PhD, professor of experimental photobiology at King’s College London.

Findings from the new study—published recently in the British Journal of Dermatology through an article titled “Optimal sunscreen use, during a sun‐holiday with a very high UV index, allows vitamin D synthesis without sunburn”—showed an increase of vitamin D in participants during a week of cloudless weather, with very high UV index, even when sunscreens were used properly and prevented sunburn.

“Our study, during a week of perfect weather in Tenerife, showed that sunscreens, even when used optimally to prevent sunburn, allowed excellent vitamin D synthesis,” Young noted.

Sunlight contains UVA and UVB radiation, and the latter is essential for vitamin D synthesis. Two sunscreens with the same SPF were compared. Sunscreen with a high UVA protection factor enabled significantly higher vitamin D synthesis than a low UVA protection factor sunscreen, likely because it allows more UVB transmission.

In the current study, “comparisons were made between two formulations, each with a sun protection factor of 15. The UVA protection factor (UVA‐PF) was low in one case and high in the other,” the authors wrote. “Healthy Polish volunteers (n=20 per group) were given the sunscreens and advised on correct application. Comparisons were also made with discretionary sunscreen use (n=22) and non‐holiday groups (51o5N, n=17). Sunscreen use in the intervention groups was measured. Behavior, UVR exposure, clothing cover, and sunburn were monitored. Serum 25(OH)D, was assessed by HPLC MS/MS.”

Amazingly, the high and low UVA-PF sunscreen groups showed statistically significant increases in serum 25(OH)D, which is produced during the metabolism of vitamin D in the body.

While this a small preliminary study, the research team was excited by their findings. The researchers agreed that much larger population-based, double-blind studies need to be utilized to determine if these results are true for all skin types and ethnic backgrounds and they look forward to continuing their work in the future.

“Sunscreens may be used to prevent sunburn yet allow vitamin D synthesis,” the authors concluded. “A high UVA‐PF sunscreen enables significantly higher vitamin D synthesis than a low UVA‐PF sunscreen because the former, by default, transmits more UVB than the latter.”