Vitamins: Definition & Explanations

Vitamine: Definition & Erklärungen

We've all heard of vitamins before. But do you even know what vitamins are exactly? Do you have any idea how many vitamins there are and what functions each has in our body? If the answer to these questions is no, you've come to the right place.

In this post about vitamins we explain to you what vitamins are, which vitamins there are, what their functions are and how we can absorb them into our body. You will also learn how a vitamin deficiency can occur and what side effects vitamins can have. So after reading this, you should be an expert in the field of vitamins.

the essentials in brief

  • Vitamins are micronutrients and we mostly get them from food. There are a total of 13 vitamins, which are not only structurally very different, but also fulfill different functions in our body.
  • A distinction is made between fat-soluble and water-soluble vitamins. Water-soluble vitamins are not stored by the body but are excreted through the kidneys. Fat-soluble vitamins, on the other hand, are stored in our adipose tissue and liver. Therefore, overdose is possible with fat-soluble vitamins, which is not the case with water-soluble vitamins.
  • A vitamin deficiency can be caused, for example, by malnutrition or malnutrition. Various groups of people with an increased need for vitamins, such as pregnant women, smokers or the elderly, are also at risk. A deficiency can be counteracted, for example, by taking vitamin supplements.

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Glossary entry: The term vitamins explained in detail

So that you are fully informed about vitamins, we have answered the most important questions about vitamins in the following sections. After reading, you will know, for example, where exactly the differences between the various vitamins lie, what tasks and effects the vitamins have in each case, and what possible deficiency symptoms and side effects are.

What are vitamins?

Vitamins are micronutrients which, with a few exceptions (e.g. vitamin D), which can be produced by the body itself, are ingested through food. "Vita" is Latin and means "life". So, as the name suggests, vitamins are essential for us to live and are needed for a healthy metabolism (1).

Woman bites an apple

We get most of the vitamins from food. In order to ensure a good supply of vitamins, a balanced, healthy diet is therefore of great importance. (Image source: Khamkhor / unsplash)

There are 13 vitamins in total, which differ greatly from each other structurally. Unlike many other nutrients, they are not used to generate energy, but each have very specific functions. They often serve, for example, as cofactors for enzymes, as hormones or as antioxidants (2).

Vitamins can not only be ingested through food, but are also available as medicines or dietary supplements, and are also contained in many cosmetic products, among other things.

A general distinction is made between water-soluble vitamins and fat-soluble vitamins. Where exactly the difference between these two types of vitamins lies and what distinguishes them is explained in more detail in the following sections.

What are water soluble vitamins?

The water-soluble vitamins include a total of nine vitamins. As the name suggests, they are water-soluble and excess vitamins are therefore not stored by the body, with the exception of vitamin B12, but are excreted via the kidneys. This makes overdosing almost impossible.

However, for the same reason, care must also be taken to ensure adequate supply. The water-soluble vitamins include the B vitamins, vitamin C and folic acid. They are usually very sensitive to heat. Therefore, foods containing these vitamins should be consumed as fresh as possible (3.4">.

What are fat soluble vitamins?

Fat-soluble vitamins include vitamins A, D, E, and K. Fat-soluble vitamins are absorbed through the gut and, if not processed, are stored in adipose tissue and the liver. Therefore, an overdose is quite possible if the intake is too high, for example through vitamin preparations.

In contrast to water-soluble vitamins, fat-soluble vitamins are considered to be quite heat-resistant. They can be found in many fatty plant and animal foods. Adding fat can help for optimal absorption (3.4">.

What vitamins are there and what are their tasks?

Below you will find a list of all 13 vitamins, as well as their tasks in the human body and sources from which they can be absorbed.

vitamin function Sources (e.g.)
Vitamin A - Important for the visual process - Protection for skin and mucous membranes - Antioxidant effect - Cell growth and cell differentiation - Red peppers - Liver - Tuna - Egg yolks - Dairy products - Carrots
Vitamin D - Bone health support - Affects muscle strength - Can be formed by exposure to sunlight - Fish - Dairy products - Egg yolks - Mushrooms
vitamin E - Cell protection - Antioxidant effect - Dairy products - Oils - Nuts - Soybeans - Eggs
vitamin k - Important for blood clotting - bone formation - Leafy green vegetables - Legumes - Eggs - Liver
Vitamin B1 (thiamine) - Energy production from food - growth - water balance - muscle building - Legumes - Potatoes - Whole grains -Poultry
Vitamin B2 (Riboflavin) - Important for energy metabolism - Cell growth - Defense - Antioxidant effect - Dairy products - Meat - Fish - Eggs
Vitamin B3 (Niacin) - Supports metabolic reactions in cells - Important in cell division - Animal products (e.g. poultry and game)
Vitamin B5 (pantothenic acid) - Important for fat and carbohydrate breakdown - Protein and fat synthesis - Production of cholesterol - Formation of hormones - Legumes - Vegetables - Milk - Meat - Fish - Whole grains - Nuts
Vitamin B6 (pyridoxine) - Important in the formation of red blood cells - Important component of coenzymes - Involved in the metabolism of amino acids - Meat - Fish - Legumes - Whole grains - Bananas
Vitamin B7 (biotin) - Important for the health of skin, nails and hair - liver - egg yolk - yeast - nuts - oatmeal - soybeans
Vitamin B9 (folic acid) - Important for growth and cell structure - Important for the metabolism - Prevention of cardiovascular diseases - Milk - Whole grains - Oranges - Egg yolks - Liver - Leafy greens - Soybeans
Vitamin B12 (cobalamin) - Important for the breakdown of fatty acids - breakdown of red blood cells - heart health - cell growth and cell division - Meat - Fish - Eggs - Dairy products - Liver - Sauerkraut
Vitamin C (ascorbic acid) - Important for the immune system - Important for the connective tissue - Iron utilization - Citrus fruits - Acerola cherry - Black currants - Peppers - Potatoes - Broccoli

How many vitamins do you need?

In order to stay healthy and fit, the body must be adequately supplied with all 13 vitamins. It is not very easy to determine how much of the various vitamins you need. This is because the amount required depends on many different factors such as age, gender, lifestyle (e.g. smoker or non-smoker) and other circumstances (e.g. pregnancy or illness) (8).

In contrast to carbohydrates or proteins, the body only needs very small amounts of vitamins. However, since these are of great importance for a wide variety of metabolic processes, it is very important to ensure that they are properly supplied.

Since many vitamins are sensitive to oxygen, light and heat, vitamin losses can quickly occur during storage or cooking.

In order to preserve the vitamins as well as possible, the food should be stored briefly and in a cool and dark place. It can also help to prepare them just before eating.

To find out your individual vitamin requirements, you can use the vitamin tables as a guide. You can get this and other interesting information about vitamins from the German Society for Nutrition (DGE), for example.

How can a vitamin deficiency occur?

With a balanced diet, the vitamin requirement should actually be covered without any problems. In Europe, the supply of vitamins is generally good and deficiency diseases only occur in rare cases. However, undernutrition or malnutrition or absorption disorders can still lead to a vitamin deficiency (5).

Groups of people with an increased need for vitamins are particularly at risk. These include, for example:

  • pregnant women
  • breastfeeding
  • vegan
  • Individuals with certain medical conditions (eg, inflammatory bowel disease or atrophic gastritis)
  • Seniors
  • teenager
  • smoker
  • alcoholic

Depending on which vitamin you are deficient in, there can be different signs. For example, dry hair and flaky scalp can indicate a vitamin B7 (biotin) deficiency. Bloody, irritated gums and a weakened immune system, on the other hand, can be signs of a vitamin C deficiency (6).

In some cases, dietary supplementation with vitamin preparations can be useful.

Since there is a risk of overdose, especially with fat-soluble vitamins, the intake of vitamin supplements should be discussed with a doctor or pharmacist beforehand.

It is also important to note that dietary supplements should only be used as a supplement and cannot replace a healthy, balanced diet.

Do vitamins have side effects?

Vitamins are usually well tolerated. In individual cases, however, hypersensitivity reactions or digestive disorders can occur. Too much intake can lead to an overdose.

An overdose is hardly possible through diet alone. However, taking vitamin supplements as dietary supplements can easily lead to an overdose. This is especially the case with fat-soluble vitamins, as these are not excreted through the kidneys.

However, it is often difficult to decide when an overdose has occurred. Up to three times the reference value, one usually does not speak of an overdose. The symptoms are often not clear either. For example, an overdose of vitamin C can cause diarrhea. Excessive vitamin A consumption can lead to headaches, vomiting and dizziness. Overdoses of vitamin D and vitamin A have also led to poisoning (7).

Vitamin C capsules...

with slow release technology!

  • Vegan, free from sugar and gluten 🌿
  • for a stronger immune system 🤗
  • automatically get 21% discount if you buy now 💰


Vitamins are essential micronutrients that we mostly absorb through food. They fulfill different functions in our body and often serve as cofactors of different reactions. Water-soluble vitamins are excreted via the kidneys, which is why you should make sure you get enough of them. Fat-soluble vitamins are stored in the body. Therefore, especially if you take additional vitamin supplements, you should make sure that you do not overdose on them.

A vitamin deficiency can manifest itself through a variety of symptoms. People with malnutrition or undernourishment, as well as certain groups of people, such as pregnant women or smokers, are more often affected. If you have a deficiency, you should first clarify with your doctor or pharmacist whether taking a vitamin supplement might make sense.

  1. Pharmacy review (2019). vitamin dictionary.
  2. PharmaWiki (2020). vitamins.
  3. Academy for Sport and Health (2020). Vitamins and their function in your body.
  4. AOK (2019).Vitamins: What are the differences between water-soluble and fat-soluble?
  5. The Technicians (2020). Vitamins: Important for a functioning metabolism (1/14).
  6. Liebscher & Bracht (2020). 6 TYPICAL SIGNS OF VITAMIN DEFICIENCY.
  7. Pharmacy review (2018). Is an excess of vitamins harmful?
  8. Carola Felchner (2019). Vitamins – vital tiny things. NetDoctor.


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