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Sunbathing is an inseparable part of summer. During the months when the sun is at its highest in the sky, spending time in swimwear by the water is the perfect way to relax. Under ideal conditions, the result is a beautiful bronze tan, which is generally aesthetically pleasing. Of course, ideal conditions mean using proper protection, such as sunscreen with an adequate SPF, and ensuring a healthy dose of sun exposure. Along with tanning, you can also enjoy the benefits of increased vitamin D production, which is incredibly important for overall health.
During the months when sunbathing might not seem like the best idea, some people opt for sunbeds, which can achieve the same result—beautifully tanned skin—in a shorter amount of time. But what is the difference between sunbathing and using a sunbed? Can sunbeds help you produce vitamin D during the winter months? What are the risks associated with sunbathing versus using a sunbed? We’ll answer all these questions (and a few more) in this article.
What is a Tan and How Does it Form?
While it may seem purely aesthetic at first glance, tanning is actually the skin’s defensive response to ultraviolet (UV) radiation from the sun. This UV radiation primarily consists of UVA (95%) and a smaller portion of UVB (5%). The most dangerous UVC radiation does not reach the Earth’s surface. [1]
UVA radiation is responsible for tanning, whereas UVB rays cause sunburns, leading to skin damage. A tan develops when UV radiation penetrates the skin and triggers cells whose job is to protect the skin from potential damage due to sun exposure. These cells are called melanocytes.
Melanocytes make up about 1% of all skin cells, and each is connected to several neighbouring cells. In response to UV radiation, melanocytes produce melanin. Melanin then spreads to the surrounding skin cells, causing an even darkening of the skin. [2]
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Tanning Depends on Skin Type
The speed and intensity at which the sun tans or burns our skin largely depend on our skin’s pigmentation. The differences in skin colour are not due to the number of melanocytes but rather their activity level and the type of melanin they produce. The most common form of melanin across all skin types is eumelanin. This dark form of melanin is responsible for the darker pigmentation of skin and hair. The second form of melanin is pheomelanin, which is found in higher quantities in people with red hair. People of Asian descent typically have roughly twice the amount of eumelanin compared to those of European descent, while people of African descent may have up to six times the amount.
The protective role of melanin is evident from the incidence of skin cancer. People of African descent have up to 70 times lower risk of developing skin cancer compared to those with light skin.
- Dark skin allows only about 17% of UVA and 7% of UVB radiation to penetrate.
- In contrast, light skin, typical of those with European ancestry, allows as much as 55% of UVA and 24% of UVB radiation to pass through.
Melanin in people of African descent is also more resistant to degradation and remains in the skin permanently, whereas the tan in Europeans typically lasts around 10 days. However, this duration can be extended with regular sun exposure. [2]
Melanin Can Be Dangerous
Despite its protective role during tanning, melanin can become harmful when exposed to intense sunbathing and UVA radiation, as it may interact with the DNA in skin cells, leading to oxidative stress.
Pheomelanin, in particular, is more prone to degradation under such conditions. People with fair skin and red hair, who typically have higher levels of pheomelanin, are therefore at greater risk for developing skin cancer and should take extra precautions to protect their skin.[3]
Tanning Produces Vitamin D
While UVA radiation can give us a tan, it doesn’t stimulate the production of vitamin D in the skin. This crucial process requires UVB radiation. Even though UVB accounts for only 5% of the UV radiation that reaches the Earth’s surface, it is sufficient to trigger a chemical reaction in the skin, converting 7-dehydrocholesterol into vitamin D.
Vitamin D is vital for bone health as it aids in calcium absorption. It can also help alleviate symptoms of depression, boost the immune system, and better regulate inflammation.
According to the European Food Safety Authority (EFSA), the recommended daily intake of vitamin D is 15 µg. How much vitamin D is produced by sun exposure?
If the entire body is exposed to sunlight for 15-20 minutes, resulting in a light pinkness of the skin, approximately 250 µg of vitamin D can be produced. This amount is several times higher than the daily requirement.[4]
Prolonged sun exposure without adequate protection, however, does more harm than good, and can lead to sunburn and skin damage. Once the maximum vitamin D production is reached, the body has a safeguard mechanism that produces inactive metabolites, meaning that longer sun exposure won’t result in more vitamin D.[4]
While sunscreens with SPF do block UV radiation from penetrating the skin, they do not completely block vitamin D production under real-world conditions.[5]
During the winter months or due to the constraints of modern life, exposure to sunlight may decrease, making it advisable to supplement vitamin D through diet or supplements. Good dietary sources of vitamin D include salmon (66% of the daily requirement per 100 g), sardines (24% of the daily requirement per 100 g), eggs (5% of the daily requirement per 100 g), or mushrooms and lichens that have been exposed to sunlight.
How Do Tanning Beds Work?
Tanning beds provide a quick and efficient way to achieve a bronzed glow year-round. Instead of lying in the sun for hours, you can obtain a tan in just 5 minutes using a tanning bed. In the past, this convenience made tanning beds extremely popular. However, research findings on their health effects and subsequent regulations have led to a significant decline in their use, with more than half of former users now avoiding them.
Unlike sunlight, which contains light of various wavelengths, tanning beds predominantly emit UVA radiation. This type of radiation stimulates the production of melanin, leading to a tan. Modern tanning beds also emit a small amount of UVB radiation, which, although it can cause sunburn with prolonged exposure, also helps in the production of vitamin D. Manufacturers strive to adhere to limits set by the European Commission, based on long-term observations that tanning beds increase the risk of melanoma.
Numerous studies have confirmed the link between regular use of tanning beds and an increased risk of melanoma. Meta-analyses of these studies indicate that the risk of developing melanoma significantly increases (by up to 27%) if you visit a tanning bed 10 or more times per year.[6]
The concentrated UVA radiation in tanning beds stimulates the production of free radicals, causing oxidative stress in the skin. Besides increasing the risk of melanoma, it also leads to premature ageing of the skin and the formation of wrinkles.[7]
New Trend – Collagen Tanning Beds
Collagen tanning beds, which promise increased collagen production to rejuvenate and regenerate the skin, operate differently from traditional tanning beds. While conventional tanning beds use UV radiation for tanning, collagen tanning beds rely on infrared (IR) radiation, which we commonly perceive as heat.
Infrared lamps have been on the market for several decades and can indeed assist in treating and regenerating skin issues. However, there are still many unanswered questions in science regarding infrared radiation, and collagen tanning beds, which are becoming increasingly popular, often promise more than they can actually deliver.
It’s also important to note that manufacturers often combine tanning with collagen production, so most of these tanning beds also emit UV radiation. The combination of UV, which damages the skin, and IR, which is supposed to help it, suggests that claims about their miraculous effects might be somewhat exaggerated.
Which Form of Tanning is Better?
Natural sun tanning comes with both risks and benefits. The radiation that reaches the Earth’s surface not only tans the skin but also stimulates the production of large amounts of vitamin D. With natural tanning, you can control how long you spend in the sun, avoiding unnecessary health and aesthetic risks. Proper protection ensures minimal risk of sunburn and skin damage, which in the worst cases can lead to skin cancer.
Tanning beds are available all year round and are effective, but despite international regulations, there is still a risk that the emitted UV radiation does not meet safety standards, increasing health risks such as a higher likelihood of developing melanoma. Additionally, the intense UVA radiation is responsible for accelerated skin ageing. Unlike sunbathing by the water, tanning in a bed is quick and lacks the other enjoyable activities you might engage in at the beach.
At first glance, it’s clear that controlled sun tanning, which can make summer days more enjoyable, is the safer alternative. However, it’s crucial not to forget proper protection. With the right precautions, sun tanning is certainly a better choice than lying in an enclosed space where carcinogenic radiation is emitted from a very short distance.
[1] IARC Working Group on the Evaluation of Carcinogenic Risks to Humans – https://www.ncbi.nlm.nih.gov/books/NBK304366/
[2] Brenner, M. and V.J. Hearing - The protective role of melanin against UV damage in human skin. – https://onlinelibrary.wiley.com/doi/10.1111/j.1751-1097.2007.00226.x
[3] Ito S, Kolbe L, Weets G, Wakamatsu K. Visible light accelerates the ultraviolet A-induced degradation of eumelanin and pheomelanin – https://onlinelibrary.wiley.com/doi/10.1111/pcmr.12754
[4] Mostafa WZ, Hegazy RA. Vitamin D and the skin: Focus on a complex relationship: A review – https://doi.org/10.1016/j.jare.2014.01.011
[5] Neale, R E et al. “The effect of sunscreen on vitamin D: a review.” – https://doi.org/10.1111/bjd.17980
[6] Dessinioti, C.; Stratigos, A.J. An Epidemiological Update on Indoor Tanning and the Risk of Skin Cancers.– https://doi.org/10.3390/curroncol29110699
[7] Lan CE, Hung YT, Fang AH, Ching-Shuang W. Effects of irradiance on UVA-induced skin aging – https://doi.org/10.1016/j.jdermsci.2019.03.005
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