family walking on the beach

What vitamin D is and what it is for

Vitamin D is a fat-soluble vitamin from which the hormone calcitriol is obtained by the synthesis in the body. It is also called the “vitamin of the sun” because the body needs sunlight to convert provitamin to vitamin D3. It is an important substance that the body needs for essential functions.

The body can store vitamin D in the liver and adipose tissue, thus ensuring supply during the winter months. However, many people suffer from a lack of vitamin D in winter, which can cause some health problems.

Daily need cannot be guaranteed through diet. Regular exposure to the sun is essential for the formation of vitamins.

Our body needs vitamins to survive. They are involved in important metabolic processes, ensure that all important functions of life are preserved, and are also good for our overall performance.

Normally, the human body cannot produce vitamins by itself, so the basic components are consumed primarily through nutrition. But vitamin D is an exception.

Vitamin D is not really a classic vitamin. It originally belongs to hormones because, and this is the difference with most vitamins, it can be produced by our own body.

Therefore, it also has hormone-like properties. The body produces 90 percent of the vitamin from the sun’s UVB radiation. It is involved in most metabolic processes and is of enormous importance to our health.

Why does the body need vitamin D?

A sufficient supply of the vitamin is extremely important for everyone, as it is involved in many metabolic processes. When research on vitamin D began, the focus was solely on the function of bone and muscle health.

However, in the course of the investigation, the much more versatile properties and functions of the vitamin for our body and our health became clear.

In the body, vitamin D assumes many important tasks, especially in the area of ​​the immune system and cellular function. The sun’s vitamin can regulate important body processes. For example, regulate the division of body cells.

Therefore, all areas of the body depend on a sufficient level of the vitamin for its normal function. It also plays an important role in the immune system’s response to both external and internal stimuli.

The regulation of the immune response, that is, the body’s reaction to bacteria, viruses, or allergens, depends largely on the adequate supply of vitamin D to the body.

In addition, there is a close connection with calcium metabolism, so the vitamin is also responsible for the health of bones and teeth.

Function for bone health

Vitamin D is responsible for ensuring that our bones remain healthy by regulating the body’s calcium balance. That means it is compatible with calcium storage.

Calcium is extremely important for bone health. Vitamin D helps bones grow normally and develop in a healthy way. It also counteracts the body’s own processes, which promote bone loss.

Muscle function

Vitamin D also helps keep muscles healthy. Muscle functions are normally maintained by this vitamin. The vitamin content in the blood is part of how our muscles work.

What was known relatively early about vitamin D is that it has a positive and supportive effect on the level of calcium in the body. It ensures that the calcium in the intestine is absorbed and the body receives it.

Function for calcium-phosphorus absorption

The vitamin is also involved in various production processes of other hormones and proteins, which among other things control the use of calcium. It promotes the absorption of calcium from the intestine and ensures that calcium is absorbed back into the kidney.

Your body needs vitamin D to be able to absorb the necessary amount of calcium. So if you have a deficiency, your body will be short of calcium. Calcium is extremely important for bones, teeth, hair, immune system, muscles, and nerves.

Vitamin D also controls the absorption of phosphorus in the intestine. The vitamin absorbs the body’s phosphorus through nutrition and helps the body metabolize energy and build bones. On the contrary, phosphorus also promotes the conversion of the vitamin in the effective ways that the body needs.

By the way, phosphorus and calcium are among the most common minerals in the body and, therefore, are very important for your health.

Function for teeth

Speaking of the interaction between calcium and vitamin. It is known that calcium is also important for teeth. As already mentioned, calcium cannot be absorbed and used properly without vitamin D and a deficiency of it would damage your teeth.

Function for the immune system

Without an intact immune system, you are simply sick. The sun’s vitamin controls and strengthens the immune system. Exact connections are still being investigated on how exactly the vitamin influences the immune system.

The vitamin D hormone called calcitriol, for example, acts in the body as a messenger for immune cells. The so-called vitamin receptors are found in immune cells. The vitamin interacts with them and, therefore, initiates important processes of the immune system.

Function for cell division

The properties of the vitamin against cancer are being investigated. It is said to be relevant for cancer prevention because it would interfere with cell identity and cell division. It is clear that vitamin D is an instrument of cell division.

And this in turn affects the cell cycle. Therefore, the vitamin could also have a positive impact on cancer. Vitamin D contributes significantly to the health of organs, skin, and hair.

The forms of vitamin D

The vitamin is available in five different forms or versions because in the body the vitamin goes through different stages of development.

  • Vitamin D1: Ergocalciferol and Lumisterol
  • Vitamin D2: Calciferol or Ergocalciferol
  • Vitamin D3: Cholecalciferol
  • Vitamin D4: Saturated form of vitamin D2, also called 22,24-dihydroergocalciferol
  • Vitamin D5: Sitocalciferol

When we talk about vitamin D in the vernacular, we really mean vitamin D3. Cholecalciferol becomes calcitriol, a hormone, and only then does it have a healthy effect on the body.

It is this form of the vitamin that is present in all human bodies or can be formed there. Vitamin D3 regulates the calcium content in the body and has a positive effect on bone structure.

tropical beach with turquoise waters

What is the requirement?

There are two main sources for the supply of vitamin D: the most important is the sun, through which we receive 90 percent of the vitamin supply. The body’s own vitamin is formed by sunlight or UVB radiation from the sun on the skin. The second source, the remaining 10 percent, are certain foods.

There are now different units of measurement to describe the correct supply of vitamins. On the one hand, there is talk of a recommended amount of 30 nanograms/milliliter, on the other hand, 1,000 to 2,000 international units (IU) per day (for adults).

Mostly, however, there is talk of 30 to 60 micrograms daily.

Depending on the country where you reside it may be more or less easy to receive the necessary solar supply. This applies particularly to the autumn and winter months when the sun is simply too weak.

This deficit generally cannot be compensated with food, unless you want to consume 27 liters of milk, 15 eggs or 2 kilograms of cod per day, for example, which is a real stupidity.

If you eat a healthy diet, you usually take two to four micrograms of vitamin D in your diet. Depending on the type of skin, it is recommended to be in the sun for 10 to 20 minutes daily to ensure the supply of vitamins.

Where does vitamin D come from?

The body can produce vitamin D by itself, but for this it needs sunlight. The starting material for this synthesis is ProVitamin 7-dehydrocholesterol. It is a sterol, which is also the precursor of cholesterol.

Sterols are important components of the cell membrane. If the body absorbs enough sunlight through the skin, ProVitamin D3 will first form in the liver.

It is then transformed into vitamin D in the kidney and the body processes or stores it. In addition to the liver, an important location for vitamin D is also fatty tissue.

Vitamin D deficiency

Vitamin D deficiency can be dangerous. Almost all cells in the body have vitamin receptors, which ensure the functionality of the respective cells. If we lack vitamins, all our health can be damaged.

The most common cause is usually lack of sun. The diet itself only plays a subordinate role. When the sun does not shine enough, the body takes advantage of its sunny day reserves and increases its vitamin D intake through its diet.

Those who eat a low-vitamin diet increase the risk of a deficiency.

Common causes of a deficiency:

  • The lack of sun.
  • Dark skin type, because the darker the skin, the more sun is needed.
  • Age, because with increasing age, the skin’s ability to form vitamin D decreases more and more.
  • Sunscreens can reduce absorption.
  • Long clothes or veils.
  • Certain skin diseases can reduce the formation of vitamin D
  • Vegan or vegetarian diet.
  • Absorption disorders of the body.
  • Medications that interfere with the use of the vitamin.

Common risk groups:

  • old people.
  • People who are often indoors.
  • People with dark skin tones.
  • Sick or bedridden people.
  • People who trust sunscreen creams.

How is the lack of vitamin evident?

The symptoms of lack of vitamin D can be very diverse. Some of them are even serious for health. The most common signs of a deficiency include fatigue, sagging, difficulty concentrating, headache and poor performance.

Since the immune system is affected, there may also be a greater susceptibility to infections or general immunodeficiency and respiratory diseases. Dizziness, circulatory problems are also common, but rarely diabetes and cardiac arrhythmias.

The nerve and brain can also be affected by the deficiency. Neurological diseases, dementia, depression, and nerve pain may occur. With a prolonged deficiency, bones and muscles are also affected.

There is an increased risk of falls and broken bones, but also rickets, osteomalacia or osteoporosis can be far-reaching consequences of vitamin deficiency. Muscles may weaken or hurt and you have cramps more often.

How to avoid it?

But you don’t have to worry, this can be avoided quite well by going out in the sun regularly or, in case of doubt, by taking vitamin D supplements that replenish the necessary levels.

If you think you may have a deficiency, your family doctor can do a blood test and easily determine if that is the reason for your symptoms. If your vitamin level shows only slight deficiencies, dietary supplements are recommended.

These are often combined products in which vitamin D3 has been enriched with other vitamins and minerals. If the vitamin level was much lower than it should be, you will generally receive an increase in the initial therapy so that the level of vitamin D in the blood is restored quickly.

The danger of a deficiency

Vitamin D deficiency occurs especially during the winter months. If the level of vitamin D in the body falls, it can have a variety of effects. Since both the immune system and basic cellular function require vitamin D, the deficiency is dangerous.

A reduced immune defense can lead to an immune deficiency, which can manifest itself in susceptibility to infections, fatigue, exhaustion, or even depression. The connection with calcium metabolism also affects the bones.

Bone and joint pain, rickets, osteoporosis and bone reduction are some of the signs of vitamin D deficiency.

Muscle weakness and burnout syndrome can also occur.

kid playing in the countryside

Vitamin D in food

Even if we only eat 10 percent of the vitamin D we need through our diet, we should monitor a diet rich in vitamins. However, only a few foods contain this vitamin in large quantities.

And in reality, there are no foods that contain so much vitamin that our needs are 100 percent covered. We should consume about two to four micrograms of the vitamin a day through our diet.

The daily requirement is around 30 micrograms. That would correspond to about two kilograms of cheese and seven eggs, a day! Almost no one should be able to do that.

In the past, cod liver oil was the main supplier of vitamin D. But let’s be honest: it is fish oil and you should eat a real stupid quantity.

dairy products

  • Quark cheese (at least 20% fat).
  • Goat milk and goat dairy products.
  • Milk (at least 3.5% fat).
  • Emmental cheese, cream cheese, Camembert, Gouda, processed cheese.


Sausages and meat

  • Chicken liver, beef, and lamb.

Vegetables and fruits

  • Mushrooms, especially boletus, chanterelles, and hives.

Butter and vegetable fats


  • Especially cod, herring, salmon, turbot, sardines, eel, and oysters.

As you can see, for vegans and vegetarians in particular it is not so easy when it comes to getting foods rich in vitamin D. In general, there are almost no important D vitamins in plant foods.

It is recommended to take dietary supplements or drops of vitamin D.

Why are vitamin D drops the ideal supplements?

There are several options for additional intake of vitamin D. In addition to capsules and tablets, drops are the most common method. But why are they so good and popular?

This is very easy to answer: drops should be used sparingly and, usually, only one drop a day is enough to ensure that you are given enough vitamin D.

This means that the drops last a long time and are considered particularly productive and economical. In addition, the drops are easier to swallow than the capsules, for example.

Which has huge advantages, especially for the elderly and children. The intake is suitable for everyone, from young people to older people. Drops are considered one of the most beneficial forms of administration.

The vitamin is embedded in a natural oil and the drops generally have no harmful or artificial additives.

What is the best way to get vitamin D?

The main source of vitamin D supply is natural sunlight. However, for the sun’s vitamin to be absorbed, some prerequisites must be met.

During the summer months, a stay of approximately 10-15 minutes between 11 am and 3 pm is sufficient on sunny days to absorb enough vitamin D through the skin.

Of course, you can’t use sunscreen. The need can hardly be met through nutrition. Of course, there are foods that contain vitamin D, such as high-fat sea fish, liver, egg yolk, and avocado.

However, as we have already said, the level required by the body cannot be covered by the relatively small amounts contained in food. For the winter months, and even if there is already a deficiency, vitamin D supplementation is recommended.

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