Sunscreen lotions don't block vitamin D synthesis

Copyright HYanWong, used under Creative Commons
via Wikipedia

CANCER DIGEST – May 11, 2019 – You know that sun screen blocks harmful UVA and UVB radiation from the sun, but does it also block the production of vitamin D stimulated by sunshine? 

That’s the question researchers at King’s College London asked. Their findings appear in the May 8, 2019 issue of the British Journal of Dermatology.

"Sunlight is the main source of vitamin D," said lead author Prof. Antony Young, of King's College London, said in a press release. "Sunscreens can prevent sunburn and skin cancer, but there has been a lot of uncertainty about the effects of sunscreens on vitamin D."

In a small study involving 40 Polish volunteers who vacationed for a week on the Spanish Island of Tenerife, researchers compared the effects of two sunscreen lotions. While both lotions had a sun protection factor (SPF) of 15 one had a low protection factor for UVA radiation while the other had high protection against UVA. In addition the researchers included 22 people who lived on the island and used sun screen at their own discretion.

What they found was that both the low and high UVA protection groups showed increases in vitamin D with greater increases shown in the high UVA protection group. Among the non-holiday group vitamin D levels fell. The researchers concluded that sunscreens may be used to prevent sunburn while allowing vitamin D synthesis. A sunscreen with high UVA protection enables significantly higher vitamin D synthesis than low UVA protection.

"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."

Sources: ScienceDaily, May 9, 2019 press release and the British Journal of Dermatology