Sunscreens do not prevent vitamin D production according to a new study by the British Journal of Dermatology that includes a systematic review of 75 papers on sunscreen and vitamin D.
Vitamin D, which is vital for bone health, is produced by the skin in response to ultraviolet radiation (UVR) from sunlight. However, as well as being the primary source of vitamin D, UVR is a major cause of skin cancer, the UK’s most common type of cancer.
In recent years, global concern about vitamin D deficiency has fuelled debates on how best to achieve healthy levels of vitamin D, known as vitamin D sufficiency, while simultaneously limiting the risk of skin cancer. Concerns have been raised that sun protection methods, including sunscreen use, may be contributing to vitamin D deficiency.
Now, three separate studies have concluded that use of sunscreen does not impact on vitamin D status in the majority of people.
Sun protection and vitamin D
In the first study, funded by the EU and conducted by researchers from King’s College London, participants were split into four groups. The participants, apart from those in the control group, then went on a week-long holiday to an area with a very high UV index.
Twenty people received a broad spectrum sunscreen with a Sun Protection Factor (SPF) of 15, offering UVB protection and high UVA protection. Twenty people received a non-broad spectrum sunscreen, also SPF 15 but with low UVA protection. These two groups were told how to use their sunscreens correctly, so as to achieve the labelled SPF. In contrast, 22 people used their own sunscreen with no instructions on how to apply it, and 17 people formed a control group who remained in Poland.
Blood (serum) samples were taken from participants 24 hours before and 24 to 48 hours after the holiday.
SPF 15 sunscreens applied at sufficient thickness to inhibit sunburn allowed a highly significant improvement of vitamin D levels. Furthermore, the broad spectrum sunscreen enabled higher vitamin D synthesis than a low UVA protective sunscreen, possibly because the former, due to its composition, transmits more a little more UVB than the latter. The people who used their own sunscreens, also had significant vitamin D synthesis, but they all had sunburn. This was almost certainly because they did not use their sunscreens correctly. During the same period, the control group has a slight decline in vitamin D.
In the second study, researchers from the QIMR Berghofer Medical Research Institute in Australia, and the Australian National University, systematically reviewed all published experimental studies, field trials, and observational studies published between 1970 and 2017, totalling 75 studies, for the first time.
The researchers found that while the experimental studies - using artificial light sources in a laboratory setting - support the theoretical risk that sunscreen use may affect vitamin D, the weight of evidence from field trials and observational studies - taking place in real-life situations involving natural sunlight - suggests that the risk is low.
The researchers explain that the conditions in the experimental studies did not reflect those of the real-world so the results cannot be used to inform public health policy.
Vitamin D synthesis maintained whilst wearing sunscreen
Observational studies which reported an association between vitamin D levels and sunscreen application most commonly found a positive relationship, supporting the conclusion vitamin D synthesis is maintained whilst wearing sunscreen.
A further review which presents the findings of an international panel of 13 experts in endocrinology, dermatology, photobiology, epidemiology and biological anthropology, who reviewed scientific literature on vitamin D and sun protection prior to an evidence review meeting also concluded that sunscreen use is unlikely to affect vitamin D production and that UVA protection does not affect vitamin D synthesis.
Professor Rachel Neale of the QIMR Berghofer Medical Research Institute and lead author of the second study, said: “A common concern amongst the general public is that sunscreen use may increase the risk of vitamin D deficiency. This has the potential to undermine sun protection messages, which aim to prevent skin cancer. A 2015 survey conducted in the United States found that 20 per cent of people agreed that regularly protecting the skin leads to a risk of not getting enough vitamin D.
“These recent findings should reduce this concern, and encourage people to follow recommended sunscreen application, which could eventually lead to a reduction in the number of new skin cancer cases.”
Holly Barber of the British Association of Dermatologists, added: “The ability to achieve adequate protection from the sun to avoid sunburn, a risk factor of skin cancer, whilst not impacting vitamin D production is really encouraging. The risk of vitamin D deficiency from sunscreen has been found to be low and therefore is unlikely to outweigh the benefits of sunscreen for skin cancer prevention.
“Further research is required on SPF 30 and higher sunscreen, as this is what we recommend people use for optimal protection in real-life situations. People with dark skin types are at a higher risk of vitamin D deficiency, and lower risk of skin cancer, so further research is also required to see how these findings translate to people with dark skin types.”