A Sunscreen That Allows Vitamin D Production
It’s one of those evergreen vitamin dilemmas. Does one apply sunscreen to prevent skin cancer, or leave it off to let the skin make its own vitamin D, with the risk of sunburn? Finally, a research group led by Kockott seems to have provided the perfect solution, with a publication a couple of days ago looking at “optimizing” a sunscreen to maximize vitamin D production whilst minimizing the risk of sunburn. The Daily Mail reports that a sunscreen developed via this principle is already on sale.
In theory this is possible: whilst UVB light is responsible for both vitamin D production and sunburn, the precise wavelengths at which both processes occur are a little different. Specifically, while the peak of both sunburn and vitamin D production occur at around 300 nm, by 305 nm sunburn production is less than a quarter of the peak whilst vitamin D production is three quarters of its. Sunscreens that block wavelengths below 305 nm whilst allowing more of the higher wavelengths through can allow vitamin D production to occur at a reasonable rate whilst blocking the wavelengths that cause sunburn. The authors show that the in vitro production of vitamin D with the optimized sunscreen is 1.5 times higher than that of a commercial sunscreen at the same SPF factor.
This sounds too good to be true, right? Not so fast. While it is true that sunscreen, when applied correctly, reduces the production of vitamin D, some production still occurs. For example, Faurschou and co-workers, despite stating in the abstract that vitamin D production can be “abolished” if applied correctly, found that using sunscreen as recommended resulted in vitamin D production that was one third of the amount produced when no sunscreen was used. In a “real life” trial that randomized subjects to sunscreen or a placebo cream conducted by Marks et al., there was no significant difference in circulating vitamin D levels between either group, although the increase in the sunscreen group (11.8 mmol/l) was a little lower than for the placebo group (12.9 mmol/l). In another study that assigned people taking a winter sun break to Tenerife to two different sunscreen treatments or a control (no cream), the increase in vitamin D levels of the groups using sunscreen was approximately half of the control group (Hawk). In both cases, while the absolute increase was lower for the sunscreen group, vitamin D production still occurred.
There are likely to be two main reasons why vitamin D is still produced despite sunscreen use. Even high protection sunscreens do not block all UV light from reaching the skin. Sunscreen with an SPF of 15 block 93% of the sun (and I notice that I tan very quickly when I use SPF 15 sunscreen, indicating that I am also producing vitamin D), while SPF 30 sunscreens block 97% of the sun and SPF 50 sunscreens block 98% of the sun (information from http://www.skincancer.org/prevention/uva-and-uvb/understanding-uva-and-uvb). People who are exposed to the sun all day wearing SPF 50 sunscreen are still going to produce vitamin D – if you spend 8 hours in the sun wearing SPF 50 sunscreen, this is similar to spending about 10 minutes in the sun with no sunscreen, which is the amount recommended to maintain vitamin D levels.
The second reason is that the average person applies a much smaller amount than what is recommended: Kim and associates estimate that sunscreen is applied at only 0.5 mg per square centimeter, whilst recommendations are around 2 mg per square centimeter.
So should you use the vitamin D sunscreen instead of your regular sunscreen? In my opinion, the results are a little premature. While the proof of principle has been shown, I would like to see a real-life study, perhaps with a design similar to Dupuy, Dunant and Grob, to show that vitamin D production is better and that the sunscreen does not promote excessive sun exposure. You may want to pay the premium price* for the product in order to support more research. You may prefer to continue to use sunscreens as you normally do, which will also prevent sunburn but still allow some vitamin D production to occur – a good rule of thumb is whether you develop a tan. Vitamin D supplements also offer a source of vitamin D that does not damage the skin and is not associated with risk of skin cancer (Green, Williams, Logan and Strutton).
Dieter Kockott, Bernd Herzog, Jörg Reichrath, Kevin Keane, Michael F. Holick. New Approach to Develop Optimized Sunscreens that Enable Cutaneous Vitamin D Formation with Minimal Erythema Risk. Published: January 29, 2016 in PLOSone. DOI: 10.1371/journal.pone.0145509
Supporting citations :
Dupuy A, Dunant A, Grob JJ; Réseau d'Epidémiologie en Dermatologie. Randomized controlled trial testing the impact of high-protection sunscreens on sun-exposure behavior. Arch Dermatol. 2005 Aug;141(8):950-6. http://www.ncbi.nlm.nih.gov/pubmed/16103322
Faurschou A, Beyer DM, Schmedes A, Bogh MK, Philipsen PA, Wulf HC. The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial. Br J Dermatol. 2012 Aug;167(2):391-5. doi: 10.1111/j.1365-2133.2012.11004.x. http://www.ncbi.nlm.nih.gov/pubmed/22512875
Green AC, Williams GM, Logan V, Strutton GM. Reduced melanoma after regular sunscreen use: randomized trial follow-up. J Clin Oncol. 2011 Jan 20;29(3):257-63. doi: 10.1200/JCO.2010.28.7078. Epub 2010 Dec 6. http://www.ncbi.nlm.nih.gov/pubmed/21135266
Hawk, J. Vitamin D and ultraviolet radiation exposure - a photodermatologist's viewpoint. NIWA UV Workshop, Auckland, 15-17 Apr, 2014. https://www.niwa.co.nz/sites/niwa.co.nz/files/Hawk_UV%20Workshop_2014.pdf
Kim SM, Oh BH, Lee YW, Choe YB, Ahn KJ. The relation between the amount of sunscreen applied and the sun protection factor in Asian skin. J Am Acad Dermatol. 2010 Feb;62(2):218-22. doi: 10.1016/j.jaad.2009.06.047. Epub 2009 Dec 5. http://www.ncbi.nlm.nih.gov/pubmed/19962787
Marks R, Foley PA, Jolley D, Knight KR, Harrison J, Thompson SC. The effect of regular sunscreen use on vitamin D levels in an Australian population. Results of a randomized controlled trial. Arch Dermatol. 1995 Apr;131(4):415-21. http://www.ncbi.nlm.nih.gov/pubmed/7726582
* I surveyed the price of the vitamin D sunscreen compared to similar products on the market via the suggested seller on the product's website. While there is considerable variation in price, the median from 14 other sunscreens that I used as comparators was 40% lower than the vitamin D sunscreen.