What is Vitamin D
Vitamin D is a fat-soluble vitamin. It is also known as the sunshine vitamin because it is synthesized when the skin is exposed to the sun. Vitamin D plays an important role in bone metabolism, muscle function and the immune system.
Fat-soluble: Said of something that is soluble in fat. |
Vitamin D and cholesterol
And yes, it is thanks to cholesterol and the sun that our body synthesizes vitamin D. More precisely, the UV-B rays of the sun which will react with 7-dehydrocholesterol (a derivative of cholesterol present in our body) to form vitamin D.
So, it is good to remember the importance of cholesterol in our body because, among other things, it is thanks to him that we manage to synthesize this vitamin D.
How does vitamin D work?
Vitamin D helps control the amount of calcium and phosphate you absorb from food.
Calcium is essential for bone health. Phosphate is necessary for healthy bones, teeth, muscles, nerves and basic bodily functions.
Vitamin D comes in two forms:
- Vitamin D2 (ergocalciferol) is naturally present in certain plants.
- Vitamin D3 (cholecalciferol) is found naturally in animals and is produced by the skin when exposed to sunlight.
How much time you should spend in the sun depends on where you live, how much time you spend outdoors, and your skin pigmentation.
You can meet your vitamin D needs with either form. But generally D3 is preferred because it is better absorbed by the body, more effective and destroyed less quickly than D2.
The health benefits
Vitamin D offers many health benefits.
Strengthens bones and muscles
BoneVitamin D ensures proper absorption of calcium, an essential element for bones. In the presence of a vitamin D deficiency, the body cannot assimilate calcium from food and must take it from our bones.
This can lead to the following pathologies:
- Bone fragility
- fractures
- Osteoporosis

muscles
Calcium is an essential element for the muscles. It helps muscle proteins to do the work of contraction.
This means that being deficient in vitamin D causes a lack of calcium and therefore, consequently, muscle loss.
In summary, vitamin D is important for strong bones and muscles, it increases bone density and muscle mass.
Strengthens the immune system
Vitamin D boosts immunity and helps fight infection by regulating the activity of immune cells that trigger antiviral and antibacterial responses.
It activates and stimulates the innate and adaptive immune systems.
Innate immune system: Immediate defence, first barrier against infectious agents Adaptive immune system: Second barrier, the body recognizes infectious agents and acts accordingly |
Research has shown it can help prevent:
- Acute respiratory infections
- pneumonia
- Covid-19
Improves mood
Vitamin D is active in regulating the feel-good hormone: serotonin.
This is why a cure of D can reduce fatigue and anxiety.
Improves heart function
Vitamin D also plays a role in cardiovascular health. It keeps the heart and blood vessels in good working order. A deficiency could cause:
- Diabetes
- Metabolic syndrome
- High blood pressure
And in return, an adequate level of vitamin D:
- Healthier blood vessels
- Prevention of strokes
What are the best food sources?
Although produced by our body when our skin is exposed to the sun, we can find vitamin D3 in our diet.
Here is a non-exhaustive list of foods that can provide vitamin D3:
- Cod liver oil
- Fish like herring, mackerel, sardines, salmon, trout, tuna
- dark chocolate
- whole milk
- Eggs
- The mushrooms
Supplementation, the solution?
Dietary supplements are the easiest way to get enough vitamin D3 every day. To avoid errors when choosing supplements, we invite you to consult our article on "How to choose your food supplements?" .
This is because it can be difficult to get enough vitamin D3 from sunlight alone, especially in winter.
Eating foods high in D3 can be difficult, so taking vitamin D3 as a dietary supplement can be beneficial.