Vitamin D: does sunscreen prevent its production Yes or No?
Vitamin D is essential to our health, but how can we obtain it while protecting our skin from the sun?
What is Vitamin D?
Vitamin D is made up of two main forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). It plays a crucial role in bone and muscle health, as well as in the proper functioning of the immune system. Despite its importance, a large proportion of the population does not consume enough vitamin D.
How does our body synthesize vitamin D?
The main source of vitamin D comes from exposure to the sun. When the skin is exposed to UVB rays, the 7-dehydrocholesterol in the epidermis is transformed into pre-vitamin D3, which is then converted into active vitamin D3. This vitamin passes through the liver and kidneys before becoming biologically active.
Why do we need Vitamin D?
Vitamin D is essential for the absorption of calcium and phosphorus, necessary for the mineralization of bones and teeth. It also contributes to muscle tone and plays a role in maintaining healthy immune function.
Sun exposure and vitamin D
Sun exposure is responsible for over 90% of vitamin D production. However, UVB rays, while necessary for this synthesis, are also the main cause of sunburn and skin cancer. This raises the question of how to get enough vitamin D without damaging skin health.
Does Sunscreen Cream Prevent Vitamin D Synthesis?
The use of sunscreens, especially those with a high protection factor, is controversial in terms of its impact on vitamin D synthesis. Studies on this subject are contradictory: some show a noticeable inhibition of vitamin D production, while others observe no significant difference. The discrepancies in results can be attributed to the often imperfect application of sunscreen and the fact that even high SPF creams do not completely block UVB rays, thus allowing some vitamin D production.
Alternatives for Maintaining Good Vitamin D Levels
There are safe ways of obtaining vitamin D without excessive exposure to the sun. Vitamin D supplementation, through food supplements, is an effective solution. Foods rich in vitamin D, such as oily fish (salmon, mackerel, tuna), fortified milk and eggs, also help maintain adequate levels.
Vitamin D supplementation
For those at increased risk of vitamin D deficiency, such as people living in climates with little sunshine, the elderly, or those with dark skin, vitamin D supplementation can be particularly beneficial. Recommended doses may vary, but are generally between 400 and 800 IU per day, depending on individual needs and medical recommendations.
Sun exposure with protection
Even with the use of sunscreen, the body can synthesize vitamin D. Moderate sun exposure of 10 to 15 minutes, two or three times a week, may be enough. Visit sun creams never block 100% of UVB, thus allowing some vitamin D production.
Necessary exposure time
Exposure to the sun for short periods several times a week is recommended to maintain adequate vitamin D levels. For example, in summer, 10 minutes of exposure of the face, arms and legs may be sufficient. In winter, longer exposure may be necessary due to the lower angle of the sun and the lower intensity of UVB rays.
Importance of UV Index
The UV index, which measures the intensity of UV rays, is a crucial factor to consider. A UV index of over 3 is generally sufficient for vitamin D synthesis. In winter, or in regions with a low UV index, it's important to maximize sun exposure whenever possible, while using adequate protection.
Sunscreen, while necessary to protect the skin from the sun's harmful rays, does not totally prevent vitamin D synthesis. To maintain a good level of vitamin D, it's essential to combine moderate exposure to the sun with a diet rich in vitamin D and, if necessary, food supplements.
Source:
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VAN DER POLS J. C. & al. Sun protection and vitamin D status in an Australian subtropical community. Preventive Medicine (2012).
WULF H. C. & al. The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial. British Journal of Dermatology (2012).
BENS G. Sunscreens. Advances in Experimental Medicine and Biology (2014).
NIKKELS A. F. & al. Sunscreens block cutaneous vitamin D production with only a minimal effect on circulating 25-hydroxyvitamin D. Archives of Osteoporosis (2017).
SERRANO M.-A. & al. Contribution of sun exposure to the vitamin D dose received by various groups of the Spanish population. Science of The Total Environment (2018).
PHILIPSEN P. A. & al. Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. British Journal of Dermatology (2019).
