Previous guidelines on the optimum exposure to sunlight for vitamin D benefits may need to be revised following a new study which looked at the benefits of solar exposure against the risk of sunburn and skin cancer.
While ultraviolet radiation (UVR) from sunlight can cause sunburn and skin cancer, it also provides vitamin D which supports the development and maintenance of health bones.
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Advice given to the public is based on both the risk and benefits of exposure to UVR. However, calculating this is complex, as the impact on health varies significantly with wavelength within the sun’s UVR spectrum.
The link between specific UVB wavelengths and vitamin D production was established more than thirty years ago in skin samples. However, uncertainty around its accuracy jeopardises the risk/benefit calculations for the right amount of exposure to sunlight.
Researchers from King’s College London, with support from the NIHR Guy’s and St Thomas’ Biomedical Research Centre, set out to test the optimum UVR wavelengths for production of vitamin D.
They measured the blood vitamin D levels in 75 participants before, during, and after partial or full body exposure to five different artificial UVR sources with different amounts of UVB radiation.
They compared their findings against those predicted using the old vitamin D study and found the old study does not accurately predict the benefit from UVR exposure.
Professor Antony Young, from King’s College London, said: “Our study shows that risk versus benefit calculations from solar exposure may need to be re-evaluated. The results from the study are timely because the global technical committee, Commission internationale de l’éclairage, that sets UVR standards will be able to discuss the findings of this paper to re-evaluate the wavelength dependency of vitamin D. Further research from our group will determine the risk/benefit calculations.”
The study has been published in the PNAS.
