The sun is neither an enemy nor a miracle drug
For a long time, a tan has been associated with good health. At the beginning of the 20th century, solar exposure was even used for therapeutic purposes, notably against rickets. Then skin cancers gradually changed our view of the sun.
Today, the paradox remains: We need ultraviolet rays to make vitamin D, but excessive exposure increases the risk of skin lesions and skin cancers.
Vitamin D notably plays an essential role in bone health and muscle functioning. It also participates in the functioning of the immune system.
But do you have to spend hours in the sun to produce enough? No.
“We only need small to medium amounts to be healthy.”reminds JoAnn Mansonprofessor of medicine at Harvard Medical School and Brigham and Women’s Hospital on the BBC.
The key is therefore less to seek the maximum amount of sunshine than to find the right dose.
A few minutes may be enough… but not for everyone
For the Pr Vincent Descampsdermatologist in Bichat interviewed by Que Choisir, “In spring and summer, 10 to 15 minutes are enough to produce a satisfactory quantity.”exposing approximately 20% of the body surface.
Interviewed by Notre Temps magazine, the dermatologist Marc Perrussel evokes for his part “about 20 minutes a third of the skin between March and September” to get enough vitamin D.
Another estimate, that of Dr. Karan RajanEnglish doctor who advises on TikTok “25 minutes of sun exposure several times a week to maximize your skin’s natural vitamin D production“.
These figures may seem contradictory. They are not necessarily: the amount of vitamin D produced depends on many parametersincluding the season, latitude, time, exposed skin surface and especially skin pigmentation.
Rebecca Mason, professor of physiology at the University of Sydney, sums up the strategy in three words: “in the middle of the day, little time and often”.
Why at this time? Because UVB, necessary for the production of vitamin D, is then more present. But this obviously does not mean that you should linger in the sun without protection.
Once this short exposure has passed, vitamin D production eventually plateaus. The risk of sunburn continues to increase.
Your skin is a complete game changer
There is therefore not a valid duration for everyone. THE
phototypei.e. the way the skin reacts to UV, plays a major role. Very fair skin can burn quickly, while darker skin benefits from more natural protection thanks to melanin.
But this protection has a downside: vitamin D synthesis is slower.
A study carried out in the United Kingdom showed that in spring and summer, people with very dark skin may need around 25 minutes of exhibition at noon
to produce enough vitamin D.
“The balance between benefits and risks of sun exposure varies depending on skin type and color.reminds
Lesley Rhodesprofessor of dermatology and photobiology at the University of Manchester.
The UV index must also enter into the equation. It measures the intensity of ultraviolet radiation reaching the ground, on a scale from 0 to 11 and above.
According to the benchmarks presented by UFC-Que Choisirwe can estimate a standard erythemal dose, that is to say the quantity of UV likely to cause the onset of sunburn, by dividing 60 by the UV index. With an index of 6, this corresponds to approximately 10 minutes for a standard dose.
But be careful: this estimate does not constitute a universal “safe” duration. A very fair phototype can quickly reach its limit, while olive or dark skin tolerates more UV before turning red.
And some people need to be particularly careful: personal or family history of melanoma, numerous moles, immunosuppressive treatments or illnesses that increase sensitivity to the sun.
The right reflex: enjoy the sun without trying to tan
The researchers’ message is ultimately less complicated than it seems: no need to expose yourself for a long time to benefit from the sun.
A walk, a walk or a few minutes outside can contribute to daily exposure. Rebecca Mason emphasizes the value of short, repeated exhibitions rather than occasional long sessions.
After a few minutes, however, it is better cover your skin and protect yourselfparticularly when the UV index is high.
Because prolonging exposure does not allow vitamin D to be produced indefinitely. On the other hand, skin damage continues to accumulate.
The risks are well known: sunburn, premature aging of the skin, pigmentary disorders and skin cancers. Excessive exposure to UV rays is the main risk factor for melanoma.
The eyes are not spared. Repeated exposure can also promote certain eye damage, notably cataracts. Wearing UV filter glasses therefore constitutes important protection.
And in winter, when the sun is no longer enough?
The situation changes completely during the less bright months.
In certain regions, winter UVB is too weak to allow significant production of vitamin D. There is then no point in excessively prolonging exposure to try to compensate.
Diet can take over and, when a deficiency is identified or a particular risk exists, supplementation can be considered with a health professional.
The main thing is ultimately to move away from a binary vision of the sun. It is neither a matter of avoiding it completely, nor of seeking maximum exposure.
We only need small to medium amounts to be healthy. A few minutes, regularly, taking into account your skin, the season and the UV index: it is probably in this sobriety that the best compromise is found. The sun can remain a summer pleasure, without becoming a debt that the skin will pay years later.