Vitamin D is an important vitamin for the body. It is essential for bone mineralization and is also involved in immunity. Vitamin D behaves like a hormone, which explains why it has a global action on health. It is both anti-infective, anti-inflammatory… It also intervenes in the control of blood pressure.
Vitamin D is produced by the skin under the action of UV rays. Most of our vitamin D intake, over 80%, comes from the sun. Sun exposure is therefore very important to meet our needs.
In our latitudes you can fill up on vitamin D by exposing your forearms, face and neck for about a quarter of an hour, without sunscreen, from April to October, but it is much more complicated in autumn and winter, with the lack of sun and in particular UVB.
It is estimated that about 40% of the population lacks vitamin D, that is, having a blood level below 20 nanograms per milliliter, especially in late winter. 6% would be in real deficiency.
Foods richest in vitamin D
Vitamin D is also found in food, in oily fish, in dairy products, in egg yolks, in certain mushrooms… But diet alone only regulates a very small part of the problem. Their contributions are limited and constitute only 10 to 20% of our needs. There is cod liver oil, which contains a lot of vitamin D. Our ancestors gave it to children to prevent rickets. But its taste is not appreciated by everyone.
All this explains why supplementation is often prescribed in winter, in the absence of official recommendations. This is even more true for the elderly because, even if they are exposed to the sun, they synthesize vitamin D less well. at the skin level”, Pr Cédric Annweiler, geriatrician at the CHU of Angers, explained to me.
Who needs to supplement?
In a recent opinion, the Haut Conseil de la santé publique does not recommend vitamin D supplementation for the general adult population. He believes that there are no solid scientific studies confirming its benefit in healthy people.
It’s true that studies have shown that a vitamin D deficiency correlates with an increased risk of infections, cancers, and cardiovascular problems. But beware of the shortcut, correlation does not mean causation, and at this stage nothing serious has yet been shown about the supposed protective role of vitamin D supplementation against the appearance of these diseases.
Furthermore, we cannot say that supplementation is completely risk-free.. Therefore, it is not recommended to take vitamin D in self-medication. Agathe Billette de Villemeur, a public health doctor and epidemiologist, points out that “today the benefits of supplementation are only proven in cases of osteomalacia – when you have soft bones – associated with a true deficiency, that is, a blood level of less than 10 nanograms per milliliter.
For people particularly at risk of vitamin D deficiency, such as the elderly living in institutions, the obese, or those with highly pigmented skin… the question of supplementation can be discussed on a case-by-case basis with your doctor.. However, the scientific data is not sufficient to recommend systematic supplementation.