Vitamin D is needed to absorb calcium from the diet into the body. It is therefore important for the growth and maintenance of solid bones and teeth. In addition, vitamin D plays a role in the proper functioning of the muscles and the immune system. Sunlight is the most important source of vitamin D. The body can produce vitamin D itself under the influence of sunlight in the skin. Vitamin D is also found in food: especially in fatty fish, and with lower levels in meat and eggs. For young children, the elderly, people with tinted skin color, people who do not get out a lot and pregnant women, the advice is to take extra vitamin D.
Description
Vitamin D is a fat-soluble vitamin. Vitamin D is one of the few vitamins that the body can make itself. Under the influence of sunlight, vitamin D is formed in the skin. In addition, the diet provides vitamin D.
Vitamin D2 and vitamin D3 in the diet
Vitamin D occurs in the diet in 2 forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3).
- Both forms are formed under the influence of ultraviolet radiation (UV radiation). This radiation is part of sunlight. Vitamin D2 is formed in certain fungi and fungi and vitamin D3 in the skin of humans and animals. That is why vitamin D3 naturally occurs in foods of animal origin.
- Both vitamin D2 and vitamin D3 are used in supplements and fortified foods. Both forms are active, so they do their work in our body. Vitamin D3 does have a slightly stronger effect than vitamin D2.
Intake of vitamin D
Vitamin D is best absorbed in the intestine when fat or oil is also present. The average intake of vitamin D from the diet is estimated at 80%. The body can store vitamin D in adipose tissue and organs, such as the liver.
Vitamin D in the body
In the liver, vitamin D is converted to 25-hydroxyvitamin D. This form is not active in the body but the level in the blood is suitable to determine if the amount of vitamin D in the body is sufficient. In the kidneys 25-hydroxyvitamin D is then converted into 1,25-dihydroxyvitamin D. This is the active form of vitamin D.
Sources of vitamin D
Vitamin D is naturally found in oily fish, such as herring, salmon and mackerel. Meat and eggs also supply vitamin D, but less than fatty fish.
Health effects
The body needs vitamin D for strong bones and teeth. It ensures that calcium and phosphorus from eating are properly absorbed and recorded in the bones and teeth during growth. In addition, vitamin D is needed to limit bone decalcification as much as possible, thereby reducing the risk of osteoporosis in later life. Vitamin D also plays an important role in maintaining good muscle function.
Furthermore, vitamin D is important for proper functioning of the immune system. But it has not yet been sufficiently demonstrated that a vitamin D supplement reduces the risk of infections such as colds.
Vitamin D deficiency
A deficiency of vitamin D can cause rickets (English disease) in young children. This disease causes abnormalities of the skeleton. In adults and the elderly, osteoporosis and/or muscle weakness can eventually occur due to a vitamin D deficiency.
Too much vitamin D
A too high vitamin D intake can only occur as a result of long-term use of too many supplements. With long-term use of high doses above the acceptable upper limit (see nutritional advice below), calcium deposits may develop in the body. This does not work with a normal diet and following the advice for intake. Also, prolonged exposure to sunlight does not pose a risk of excess vitamin D. The skin then regulates the production. In practice, an overdose in healthy people is rare.
Nutritional advice
A daily recommended amount of 10 micrograms of vitamin D applies to everyone. Only people over 70 should receive 20 micrograms per day.
Many people get enough vitamin D through the sun and food. The advice is to spend 15 minutes to half an hour every day between 11 am and 3 pm with your head and hands covered in the sun. In addition, you get vitamin D when you eat according to the Schijf van Vijf, with at least halvarine or margarine, liquid baking and frying fat and fatty fish. Look for customized advice in the Disc of Five.
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