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Vitamin D: An essential vitamin for our good health!

According to studies, 80% of the French population is deficient in vitamin D. This is why more and more people are taking vitamin D in the form of capsules, ampoules or sublingually. Is this your case? Did you know that a lack of this vitamin can lead to:

  • Muscle weakness.

  • A weakening of the immune system.

  • Hair loss.

  • Osteoporosis (in the case of severe deficiency).

  • Mood swings.

…The list is longer.

A lack of vitamin D is easy to identify and with the following information, you will be able to anticipate a deficiency.

vitamine D


Vitamin D is a fat-soluble vitamin (absorbed with fat). She has many actions. Its best known role is its involvement in the metabolism of calcium and phosphorus. It helps regulate intestinal absorption and excretion of calcium. This action will have an important consequence on the health of bones and teeth since it contributes to their proper mineralization. It also works with a hormone, parathyroid hormone (PTH), which increases the level of calcium in the blood as needed. This hormone is secreted by the parathyroids (glands located around the thyroid).

Another essential role of this vitamin is its involvement in immunity. It acts as a booster of the immune system by having a modulating effect on the inflammatory reaction. It will therefore help to make the immune response faster against pathogens and therefore stimulate the defenses. It also affects DNA regulation! To say how essential this vitamin is to our proper functioning.

It is also important for the muscles since it has a trophic effect (nutrition of tissues and organs) by participating in muscle renewal. It will therefore fight against muscular instability and thus limit the risk of falls (particularly in the elderly who are very exposed to loss of muscle mass).

Finally, and this action is far from negligible, it also contributes to our mental well-being! Indeed, several studies suggest that vitamin D deficiencies could play a role in the development of depression. The latter is involved in regulating the production of serotonin (you know, this famous hormone which brings calm, serenity and good humor).

It has other important actions including:

  • On the cognitive level by acting on the functions of memory and logical reasoning.

  • In the case of the prevention of cardiovascular diseases. It would reduce inflammation, calcification of the arteries and high blood pressure.

  • In the case of type 2 diabetes by improving postprandial sensitivity (after a meal) to insulin (blood sugar regulating hormone) in the case of insulin resistance (prediabetes state).


The ideal is to have this vitamin measured in a laboratory. This dosage is no longer reimbursed (cost varying between 12 and 16 euros depending on the lab) but I can only recommend that you do this dosage in view of the important actions that this vitamin has on the body. Ideally, you can do a first dosage at the start of autumn to assess your summer stocks, and a second dosage in spring to assess the impact of winter. In dosage, the ideal is to be around 50ng/ml (if you have osteoporosis, it will be necessary to be around 50-60 ng/ml).

ANSES (National Agency for Food, Environmental and Occupational Health Safety) recommends nutritional references in vitamins and minerals for the French population. You will find these references by clicking here.


Very few foods are sources of vitamin D, but you will find it in:

  • Oily fish (sardines, herring, mackerel, anchovies, halibut, salmon, trout, tuna).

  • Certain mushrooms (chanterelles, porcini mushrooms, morels).

  • Cod liver oil.

  • The egg yolk.

  • Cheese (it contributes a small contribution).

Knowing the significant lack of this vitamin in the French population, it is recommended to supplement between October and March (contact your healthcare professional).

If your healthcare professional advises you to take a vitamin D food supplement, I will give you some additional information:

  • The unit of vitamin D is ug/day. 1 ug = 40 IU (international unit).

  • The preferred form in the case of supplementation is D3 (cholecalciferol).

  • Vitamin D should be taken during a meal containing fat (because it is a fat-soluble vitamin). The ideal is to take it every day in sublingual form (drops to put on the tongue) or once a week (dose for 7 days to be taken in one go).

  • Taking 1000 IU/day is recommended for prevention to maintain a rate (for example, you have an optimal rate and between October and March, you take 1000 IU/day to maintain this rate during the winter). If your dosage is at the low limit or if it reveals a deficiency, 1000 IU/day is absolutely not enough and your healthcare professional will advise you on a suitable dosage.

  • To be active in the body, vitamin D needs sunlight, magnesium and cholesterol.


This vitamin is therefore an important player in good health and ensuring that you are not deficient is prevention! If you want to take action for your health, don’t hesitate to make an appointment.

See you soon for a new article!


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