9 out of 10 French people lack vitamin D, yet vitamin D, also known as the sunshine vitamin, plays an essential role in the optimal functioning of our bodies. What is vitamin D? What role does it play? How can we provide our bodies with vitamin D? Find out the answers to these questions and everything there is to know about vitamin D in this article.
Vitamin D is a fat-soluble vitamin, which means that its assimilation is facilitated by the presence of fats in which it will dissolve.
Vitamin D exists in two forms: vitamin D2, also known as ergocalciferol, which comes mainly from plant-based foods, and vitamin D3, also known as cholecalciferol, which comes from animal-based foods or from synthesis by our bodies via the sun's rays (UVB).
Vitamin D can be produced in two ways:
Once ingested or synthesized by UVB rays, vitamin D is transported to the liver, where it is hydroxylated to calcidiol. In the kidney, calcidiol is transformed into calcitriol, the active form of vitamin D. It then accumulates in fat and liver, where it is stored.
Vitamin D has many essential functions in the body:
Vitamin D's best-known role is to increase the absorption of calcium and phosphorus. It regulates their absorption in the intestine and their reabsorption in the kidneys. This contributes to bone mineralization and healthy muscle function.
Vitamin D contributes to the functioning of the immune system. It activates the immune defense system, which is called upon when your body is fighting a virus or bacteria. Vitamin D stimulates the immune defense cells known as macrophages, which destroy pathogens such as viruses and bacteria. As a result, our body reacts more quickly to aggression.
Vitamin D helps reduce catabolism during exercise, thus avoiding the degradation of muscle tissue during physical activity. Vitamin D also facilitates recovery and the synthesis of testosterone, an essential hormone for muscle development.
What's more, a good level of vitamin D reduces the risk of falls in the elderly by around 30%, as it promotes good muscle contraction. Falls among the elderly should not be underestimated, as they often result in hospitalization or fractures that can have a serious impact on health.
Teeth have a hard outer layer called enamel. This is the hardest substance in the human body, and it does the job of protecting the tooth from damage and decay. When vitamin D is deficient, especially in children, the enamel is not as strong as it should be, making it easier for decay to attack the tooth.
Enamel strength is linked to a process called remineralization. This is a process in which minerals in the saliva help keep teeth strong. A sufficient amount of vitamin D is necessary for this remineralization. The stronger teeth are thanks to mineralization, the more resistant they will be to decay.
But vitamin D's role in dentition doesn't stop there. Beneath the enamel, there's another layer called dentin. It contains guard cells that protect the area between enamel and dentin, and release immune factors.
We now know that vitamin D acts during the various life stages of the cell cycle, in particular during cell division, growth and death.
Thanks to its cell-cycle modulating properties, vitamin D plays an important role in cell, tissue and organ renewal. All our body's functions are therefore involved.
Bones need calcium and phosphorus for strength. Vitamin D regulates calcium and phosphorus levels in the body by reducing their elimination by the kidneys, while at the same time increasing intestinal absorption. This ensures optimal bone mineralization and contributes to the maintenance of normal bone structure.
The majority of the French population is deficient in vitamin D, despite its importance to the body. This can be explained by a number of factors: lack of sunlight and exposure, time of year, latitude, which varies the intensity of ultraviolet rays, age, low consumption of oily fish rich in vitamin D, etc.
Low vitamin D levels can be expressed in different ways:
Although these symptoms are not specific to vitamin D deficiency, they can be warning signals sent by your body. Significant vitamin D deficiency can lead to :
Like deficiency, excess vitamin D can have side effects. In very high doses, vitamin D leads to excess calcium in the blood (hypercalcemia) and urine (hypercalciuria), and facilitates the formation of calcium oxalate kidney stones.
For healthy adults, competent authorities recommend that vitamin D intake should not exceed 115 micrograms (4600 IU) per day.
As mentioned above, vitamin D has two origins: endogenous, thanks to UVB rays, and exogenous, thanks to our diet.
It's not for nothing that vitamin D is nicknamed "the sunshine vitamin"! 60-70% of vitamin D production comes from the action of UVB rays on the skin, which convert cholesterol into vitamin D3.
So it's important to expose yourself to the sun, while taking care not to create a rash that could be harmful to your health. To do this, we recommend that you take up outdoor sports or go for a walk for 15 to 30 minutes several times a week, as soon as possible.
Even so, vitamin D reserves are quickly depleted, and there are certain times of year when you can't get enough sunshine. This is particularly true in autumn and winter, when the wavelength of UVB radiation does not synthesize enough vitamin D to cover your daily needs. So you need other sources of vitamin D, such as food or dietary supplements.
You can provide your body with vitamin D through your diet. Here is a non-exhaustive list of foods rich in vitamin D, taken from the Ciqual table (reference database on the nutritional composition of foods in France):
Foods containing significant amounts of vitamin D are rare (and not universally appreciated). This may explain why the majority of French people are vitamin D deficient!
It may therefore be beneficial to take vitamin D supplements to offset any deficiency. Even if vitamin D testing is not compulsory, don't hesitate to speak to a health professional before starting a supplementation program.
Vitamin D supplementation can make up for deficiencies caused, for example, by under-exposure to the sun or low consumption of foods rich in vitamin D. It is advisable to prefer natural forms (not synthetic forms) of vitamin D3, which is the form best assimilated by the body.
Technically, all the time (respecting the recommended daily doses), but there are obviously certain periods to focus on.
The most common course of action is to take a vitamin D cure in autumn to prepare for winter, when there is little sunshine. What's more, when winter sets in, it brings with it the cold, as well as viruses and bacteria. So it's a good idea to boost your immune system beforehand, with a vitamin D supplement.
A spring cure is also recommended, as sunshine is not yet at its peak, but we're about to re-expose ourselves to the sun and go out for walks more easily. The cure will help prepare us for these different exposures.
Supplementation can also be beneficial for athletes during preparation or intensive training, for example.
The minimum recommended duration of a vitamin D cure is three consecutive months, renewable. Supplementation should be taken with a meal to maximize absorption.
Here are a few tips to help you choose the right vitamin D supplement:
DIELEN D3+ combines a high-dose natural form of vitamin D3 (2000 IU/capsule) with its activating cofactor, magnesium. DIELEN D3+ supplements our vitamin D-deficient diet with magnesium to activate its bioavailability, i.e. its absorption by the body. All in a single capsule for easy, daily intake.
As explained above, vitamin D3 is fat-soluble. It therefore needs to be accompanied by fats to promote intestinal absorption. That's why DIELEN D3+ is the only vitamin D to be solubilized in omega-3s, which are essential fatty acids, enabling it to be better assimilated by the body.
