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According to ANSES, more than 70% of the French adult population in 2019 had a vitamin D deficiency and a case of deficiency in almost 7% of cases. The symptoms can be very violent, this vitamin being essential for the proper functioning of the human body. We explain the importance of this vitamin, its actions on the body and how to prevent a vitamin D deficiency.
Vitamin D: What is it?
Vitamin D is 90% produced by the human body. It includes five different molecules (D2, D3, D5, D6 and D7) but they are all very similar chemically.
Vitamin D3 acts like a hormone that is activated by reaction to sunlight. It is a fat-soluble vitamin, meaning it dissolves and is stored in fat. It can therefore be released slowly according to the body's needs.
What is the role of vitamin D in the body?
Vitamin D contributes to many functions within the body, such as:
- Bone (cartilage and teeth) and tissue mineralization, especially in children. A deficiency of this vitamin can cause rickets in younger people.
- Muscle contraction: vitamin D protects against muscle fiber atrophy.
- Hormonal and mood regulation: it increases the production of serotonin and keeps away the symptoms of depression.
- Prevention of certain diseases and cancers. Thanks to its immunomodulatory action, vitamin D could slow the development of autoimmune diseases such as multiple sclerosis, rheumatoid arthritis or inflammatory bowel diseases.
- Prevention of fractures and osteoporosis, a bone disease that deteriorates tissue and makes bones thin and fragile.
According to a 2012 study*, vitamin D supplementation reduces the risk of falling because muscle strength and postural balance are improved. Athletes and seniors are less likely to fall and potentially injure themselves.
Additionally, vitamin D plays a role in sports performance and tends to improve it by protecting bones from fractures and promoting recovery (according to a study by Newcastle University in 2013).
What is the difference between vitamin D2 and D3?
Among the different forms of vitamin D, we find vitamins D2 and D3 in the form of dietary supplements. These are also the best-known variants.
Vitamin D2, also called ergocalciferol, comes from plants and fungi.
Vitamin D3, or cholecalciferol, is found in animal products, but also in lichen. Also called the "sunshine vitamin," it is the one that most closely resembles vitamin D synthesized by the body exposed to sunlight and fat.
Both vitamins are metabolized in the liver to calcifediol, which releases calcitriol, the active form of vitamin D. However, vitamin D3 is thought to be better assimilated by the body and generate a higher level of calcitriol than vitamin D2.
How to recognize a vitamin D deficiency?
Vitamin D deficiency is common, especially in Nordic countries during the winter. People living or working indoors are also very affected, along with the elderly, infants and pregnant women.
The lack manifests itself through fatigue, cramps or bone pain, but also a depression of mood. It can also affect the cardiovascular system through the arrival of certain diseases, in the most serious cases.
Muscle weakness may also be felt in addition to general fatigue. Diseases develop more easily because the immune system is weakened.
Low vitamin D levels promote the development of insulin resistance and therefore diabetes. In addition to monitoring your vitamin D levels, it is important to combat a sedentary lifestyle and exercise regularly.
Vitamin D deficiency in athletes
According to a study by Constantini, 63% of participating athletes had insufficient vitamin D levels, especially for indoor athletes (80% have deficiencies, compared to 48% of outdoor athletes). This vitamin D deficiency increases the risk of fracture and makes healing slower.
It can therefore be deduced that vitamin D improves sports performance by protecting bone tissue, preventing fractures, and protects against cardiovascular disorders.
Contrary to what one might believe, high-level sportsmen and athletes are also subject to vitamin D deficiencies and are encouraged to supplement, always with the advice of a doctor. While this deficiency affects indoor athletes more (basketball players, dancers, etc.), outdoor athletes are not immune to it.
Click here to learn more about vitamin D deficiency.
Excess vitamin D
Overdose is low risk through diet and sun exposure. Dietary intake is below the recommended intake, with foods containing only a small amount of vitamin D. Food supplementation is suggested, especially for young children or people at risk. It is this vitamin supplementation that must be controlled because it can lead to an overdose and be toxic to the body.
Excess vitamin D3 leads to high levels of calcium in the blood, can lead to headaches, vomiting and intense fatigue. It is therefore important to monitor it during regular blood tests and consult your doctor before any supplementation.
Where is vitamin D found?
According to ANSES, 15 to 20 minutes of exposure to the sun per day is enough to synthesize a sufficient daily intake of vitamin D (15 μg/day for adults). In cold weather, be on the lookout for the slightest ray of sunshine to avoid winter depression for as long as possible. Exposure to the sun must be adapted according to the season, the UV index (< 3 without sunscreen) and the melanin level of the person exposing themselves.
Certain foods are rich in vitamin D, including:
- Oily fish (salmon, sardines, trout) should be eaten once or twice a week
- Egg yolk
- Milk or certain cheeses whose consumption must be limited
- Dark chocolate
- Some mushrooms, such as chanterelles, porcini mushrooms and morels
- Butter and margarine.
It was customary to take cod liver oil to benefit from its vitamin D content.
When to take vitamin D?
It is particularly in winter that vitamin D levels should be monitored. Treatments are particularly effective when taken over the duration of a sports program or to get through the winter. A treatment of a few weeks is not sufficient to benefit from the effects of the vitamin.
The recommended daily intake is generally not reached, which is why so many people have a vitamin D3 deficiency in France. Before any supplementation, seek advice from your doctor. While it is important to compensate for deficiencies, it is just as important to protect yourself from overdoses.
Nutrimuscle has chosen to partner with the supplier Quali®-D to offer high-quality and traceable vitamin D. Take one vitamin D capsule during breakfast with a glass of water.
*Bischoff-Ferrari, HA Relevance of vitamin D in muscle health. Rev Endocr Metab Disord 13, 71–77 (2012
