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Getting a tan may not depend on how much sun people receive, but rather when they receive it. This is the conclusion of a new international research project. The study, published in Molecular Cell, revealed that a sun exposure every other day was more effective for tanning and caused less damage to the DNA than a daily exposure.
This type of exposure also avoided causing skin "thickening" in people exposed to the sun every day. Thus, according to research, those who want a powerful tan, while avoiding the "aged leather" often seen among long-time sun-worshipers, would do better to take 24-hour breaks between tanning sessions.
The study also suggests that it would be possible to create cosmetics that would give people a "natural" tan, while improving our understanding of skin cancer, which kills an increasing number of people. However, none of this changes the risk of skin cancer related to sun exposure – nor to health advice regarding the reduction of exposure.
The researchers examined the impact of ultraviolet light found in sunlight on the skin of humans and mice and in cultured cells, and identified the importance of a protein called MITF. This acts as a clock, synchronizing and coordinating two systems used to protect the body from the harmful effects of sunlight. A protective process, which starts a few minutes after exposure, thickens our skin and attempts to repair the damage caused by the sun to our DNA.
The other process begins in a few hours and produces melanin, a black pigment, in specialized skin cells called melanocytes. The pigment then goes to the main type of skin cells, the keratinocytes. It is this melanin that absorbs some of the harmful UV energy produced by the sun and gives people a tanned look.
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The importance of melanin can not be underestimated because it reduces the damage caused by the sun to the DNA, which can lead to cancer. Researchers have been able to show that skin exposed to ultraviolet light experiences less damage to DNA, even though the DNA repair process was not activated as often. This is probably due to the fact that a daily exposure has produced more melanin.
The researchers showed that exposure of the skin to UV rays increased the concentration of MITF proteins in the skin. But the level of MITF does not increase and then decrease. Instead, it displays a waning oscillation, which rises and rises several times but gradually disappears over 48 hours. But the researchers also showed that if a second period of exposure started after just 24 hours, before MITF levels returned to baseline levels, different genes were activated and the result was less tanning and more pain. Thickening of the skin.
No tanning yet
It is interesting to note that previous work published in The Lancet also showed that vitamin D levels in the body were also higher when there was a 24-hour interval between exposure to the sun. Vitamin D is produced in the skin using the energy of ultraviolet rays. It is essential for the proper functioning of the immune system, the heart, the protection against cancer, sepsis and many other functions.
Read more:
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The new discoveries will be of particular interest to the cosmetics industry. They mean that it might be possible to develop products containing proteins that will stimulate the skin to develop a "natural" tan, without being exposed to the harmful effects of the sun. A tan without risk could be possible in the future.
In the meantime, research suggests that it may be better to use higher-factor sunscreen – or avoid the sun altogether – every other day. But it is important to remember that there is no safe tan. Prolonged exposure to the sun increases your risk of skin cancer. You must always wear appropriate protection every day.
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