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At the approach of winter, our body synthesizes much less vitamin D, yet essential to our body. – Ludovic MARIN / AFP
- Vitamin D, or vitamin of the sun, is synthesized by our body through exposure of the skin to the sun.
- In this season, where the sun is less present, there is the question of a possible vitamin D deficiency.
- But what is it for? What are the consequences of a vitamin D deficiency and how to avoid it? We explain to you.
It is not sunny, the night falls at 17:30. And in this happy picture, in addition to the traditional seasonal depression that seizes many of us, the morose weather conditions raise another question too often neglected: when we know that exposure to the sun is the simplest way and effective to refuel vitamin D, how to ensure its necessary contributions to the approach of winter? Do not panic, we explain.
But what exactly is vitamin D? Often described as the "vitamin of the sun," vitamin D behaves like a hormone and has multiple effects on the body. It "has a dual origin: it is provided by the diet and synthesized by the body at the skin, under the action of solar or ultraviolet rays," describes ANSES, the National Agency for Health Security.
Multiple virtues for health
We hear it all along with commercials extolling the merits of white cheeses and other enriched yogurts: vitamin D makes it possible to fix calcium on the bones, and thus to ensure good bone health. According to ANSES, "the main function of vitamin D is to increase the intestinal absorption capacity of calcium and phosphorus". It ensures the healthy growth of children and prevents the risk of fractures due in particular to osteoporosis in seniors, especially for women after menopause. But vitamin D has many other virtues. She participates in "an effective muscular contraction, good nerve transmission, adequate coagulation", but also to the good "hormonal regulation", adds ANSES.
Another reason to take care not to miss vitamin D: it would be linked to a better cardiorespiratory condition, as attested by a study published at the end of October in the European Journal of Preventive Cardiology. Researchers at Virginia Commonwealth University in the United States have shown that participants with high levels of vitamin D have better cardiorespiratory fitness than others.
"A good vitamin D status could play a protective role against certain cancers and autoimmune diseases", such as type 2 diabetes or multiple sclerosis, complete Dr. Laurent Chevallier, maternal nutritionist physician and co-author of work So what are we eating?(Fayard ed.)
Signs of a deficiency
How do you know if you are lacking vitamin D? "We talk about fatigue, depression, muscle weakness, but there is no specific symptomatology for vitamin D deficiency," says Dr. Henry Pawyn, dermatologist. According to ANSES, the recommended intake of vitamin D "is 5 μg per day in adults and children over 3 years, and 10 to 15 μg per day in the elderly". To know if one is deficient in vitamin D, "it is necessary to make to practice biological examinations and to make a dosage in vitamin D, indicates Dr. Chevallier. Reference standards for vitamin D levels have been reviewed, and since then 75 to 80% of French people are considered to have vitamin D insufficiency. "
If you do not want to fall into alarmism, "taking advantage of a visit to the doctor for a flu shot or a winter illness may be an opportunity to ask your doctor about our vitamin D level." is the right time of the year to care, "advises the nutritionist doctor in maternity. When the vitamin D level is below 30 ng / ml, it is called deficiency, and when it is less than 15 ng / ml, it is called moderate to severe vitamin D deficiency. is very severe that the most serious signs appear, such as rickets in children for example or in adults completely undernourished, "notes Dr. Chevallier.
Refuel with vitamin D
So we take care to refuel vitamin D. And, more than 90% of our vitamin D needs are covered by exposure to the sun. One of the easiest ways to recharge your batteries vitamin D is to expose yourself to the sun every day for about fifteen minutes, the face and the arms, that's enough (and not in full sun, it goes without saying! ). However, if rain and greyness punctuate tirelessly your autumn days, do not panic.
"There are two types of vitamins," says Dr. Henry Pawin, dermatologist. The water-soluble vitamins, like vitamin C, can not be stored: the body eliminates the surplus in the urine, details the dermatologist. Vitamin D is fat soluble: the body thus has the capacity to store vitamin D synthesized during the summer sunny months to build up reserves for winter in the liver, muscles and adipose tissue. So all is well if we took his right dose of sunshine during the summer period.
The problem "is that vitamin D deficiency is directly related to our lifestyles: we are much more sedentary, we walk less, we are less outside," says Dr. Chevallier. Obviously, it's difficult to synthesize enough vitamin D in these conditions. "You have to walk around, enjoy the sun and the outdoors," he says. We will also benefit from the benefits in terms of light therapy, which does not hurt in this season.
You can also load the contents of your plate in foods rich in vitamin D, focusing on fatty fish (salmon, herring, sardines), or eggs. But the effectiveness will be moderate: "the diet is only a weak source of vitamin D intake, from 5 to 10% of the needs," says Dr. Chevallier. If one is deficient in vitamin D, "supplementation must be prescribed, it is also frequently the case for babies as well as the elderly, says the nutritionist doctor. But under no circumstances should you start wild vitamin D supplementation, no matter how old you are ". In excess, it can "accumulate in the body in case of excessive supplementation and cause various disorders: headaches, nausea, vomiting, weight loss, intense fatigue," also recalls ANSES. That's why a vitamin D cure "must always be done on medical advice, insists
Dr. Laurent Chevallier, and under the supervision of his doctor ".
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