With the summer season approaching, the extent of our exposure to sunlight needs to be carefully considered. Exposure to sunlight can, indeed, be both beneficial and harmful. On one hand, sunlight exposure is physiologically important. Sunlight mediates the formation of vitamin D: an important pro-hormone that is involved in bone, cardiovascular and mental health. Vitamin D cutaneous formation (i.e. made by the skin) requires sufficient and consistent exposure to sunlight. According to recent studies, this can be achieved by simply having a midday walk of ten minutes, with exposed arms and legs and without wearing sunscreens1. On the other hand, extensive exposure to sunlight can be detrimental to the health of the skin. It can cause skin burns and other serious medical conditions such as skin cancers. It can also cause the skin to age prematurely.
Sunscreens are very effective at protecting the skin from ultraviolet radiation (UV), one of the most harmful radiations in the light spectrum. Used as lotion or gel, sunscreens can form a protective layer over the skin than can reflect a portion of the light emitted by the sun and absorb another portion. Several research studies, spanning several decades, have shown that sunscreens significantly reduce the risks of developing skin cancers such as skin melanoma and squamous skin carcinoma2.
Regular use of sunscreens can, however, interfere with the cutaneous synthesis of vitamin D by preventing ultraviolet light from reaching the skin3. As a result, regular use of sunscreens can cause vitamin D deficiency, which is believed to be a risk factor for cardiovascular diseases and certain forms of cancer. Application of sunscreens with an SPF of 15 has been shown to decrease by 95% the production of vitamin D by the skin4.
In a recent research study conducted at Boston University medical center, scientists were able to demonstrate that it is possible to selectively design a sunscreen that can effectively protect the skin from UV while still permitting the synthesis of vitamin D5. Researchers offer a method for sunscreen makers to optimize the formulation of their sunscreen for both vitamin D production and skin protection. By using different molecules that absorb different portion of the sunlight spectrum, researchers introduced Solar D5. This prototype sunscreen provides an SPF 15 skin protection while increasing vitamin D production by 50% compared to standard SPF 15 sunscreens5. Although more studies are pending, this idea could be the start of a new generation of “smart” sunscreens.
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1: Byrne, Scott N. (2014). How Much Sunlight Is Enough?. Photochem. Photobiol. Sci. 13.6, 840. Web.
2: Burnett M.E., Wang S.Q. (2011). Current sunscreen controversies: a critical review. Photodermatology, Photoimmunology & Photomedicine, 27 (2): 58–67.
3: Sayre, Robert M.; Dowdy, John C. (2007). Darkness at Noon: Sunscreens and Vitamin D3. Photochemistry and Photobiology, 83 (2): 459–463.
4: Matsuoka L, Ide L, Wortsman J, MacLaughlin J and Holick MF (1987). Sunscreens suppress cutaneous vitamin D3 synthesis. J Clin Endocrinol Metab, 64, 1165–1168.
5: Kockott, Dieter, Bernd Herzog, Jörg Reichrath, Kevin Keane, and Michael F. Holick (2016). New Approach to Develop Optimized Sunscreens That Enable Cutaneous Vitamin D Formation with Minimal Erythema Risk. PLoS ONE, 11.1 (2016). Web.