Vitamins


Vitamins are vital for us as human beings. Our body cannot produce them itself, but must take them in with our food. While we need only small amounts of them – a few milligrams or even micrograms of most of them are sufficient – they are nevertheless absolutely essential. They participate in countless biochemical processes in our body and have very many and very varied tasks to perform.

There are 13 vitamins and they are divided into water soluble and fat soluble:

Water-soluble vitamins

Fat-soluble vitamins


Vitamin C (ascorbic acid)

Functions in the body
Vitamin C is an effective antioxidant and protects us from cell damage caused by free radicals. Thus it has an anticarcinogenic effect. In addition, it strengthens the immune system and participates in detoxification reactions. In the intestine it promotes the resorption of iron from plant foods and hinders the formation of carcinogenic nitrosamines. It is also important in the synthesis of connective tissue, bones and teeth.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 100 mg of vitamin C per day.

Important food sources
The most important food sources are fruits, vegetables and potatoes. Particularly good suppliers are peppers, broccoli, leafy green vegetables, citrus fruits, strawberries, kiwis and black currants.

Deficiency
The classical vitamin C-deficiency disease is scurvy. In earlier times, this affected many seamen, who had practically no fresh fruits and vegetables to eat during their long sea voyages. They suffered from haematomas, loss of teeth and pains in the joints and limbs. It was not uncommon for scurvy to be fatal.

Luckily today, there is no longer any pronounced vitamin C deficiency with such serious consequences. However, those who eat very few fruits and vegetables must assume that their vitamin C supply is insufficient to carry out all of its important functions. What suffers above all is the immune system, and this translates into an increased susceptibility for infectious diseases. Neither can one expect an anticarcinogenic effect.

Today it is recommended to eat at least five portions of fruits and vegetables daily. The amount of vitamin C thus taken in can contribute very effectively to the prevention of cancer.

Incidentally, a particularly large number of free radicals are formed during the metabolism of smokers. In order to detoxify them, smokers require approximately 40% more vitamin C than non-smokers. Abundant, regular consumption of fruits and vegetables is therefore especially important for smokers.

 

 

Vitamin B1 (thiamine)

 

Functions in the body

Vitamin B1 is essential particularly for carbohydrate metabolism. In addition, it carries out special tasks in the nervous system and thus strengthens the ability to concentrate and the memory.

 

Recommended intake

According to the recommendations of the German Society for Nutrition, adults should take in approximately 1-1.3 mg pf vitamin B1 per day.

 

Important food sources

The important suppliers of thiamine are whole-grain cereal products, legumes, nuts, yeast and pork.

 

Deficiency

The nervous system suffers especially from an insufficient supply of vitamin B1. The results are poor concentration, tiredness, irritability and weakness.

 

A serious thiamine deficiency, which fortunately practically never occurs in industrial countries but is not uncommon in developing countries, manifests as serious neurological disorders, muscular atrophy and cardiac disturbances.

 

 

Vitamin B2 (Riboflavin)

Functions in the body
Vitamin B2 takes part mainly in catabolizing the nutrients protein, carbohydrates and fat and turning them into energy for the body.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 1.2–1.5 mg of vitamin B2 per day.

Important food sources
Particularly good suppliers of vitamin B2 are milk and dairy products, but also meat, liver, fish, eggs, whole-grain cereal products and yeast.

Deficiency
A vitamin B2 deficiency leads, among other things, to inflammatory changes of the skin and mucous membranes, especially in the mouth and on the tongue. Our intake of vitamin B2 is generally sufficient, however, and these signs of deficiency are very rarely seen.


Vitamin B6 (Pyridoxine)

Functions in the body
Vitamin B6 participates mainly in the synthesis, degradation and conversion of amino acids (the building blocks of protein). It is also necessary for the formation of haemoglobin.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 1.2–1.5 mg of vitamin B6 per day.

Important food sources
Vitamin B6 is found in most foods. Particularly good sources are meat, fish, whole-grain products, potatoes, nuts and legumes.

Deficiency
A pronounced deficiency of vitamin B6 leads to inflammatory changes of the skin, neurological disorders and anaemia. Owing to the fact that vitamin B6 is widely found in our food, a deficiency of this vitamin is extremely rare.


Vitamin B12 (cobalamine)

Functions in the body
Vitamin B12 plays many roles in our metabolism. Among others, it is important for cell regeneration and for the blood.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 3 µg of vitamin B12 per day.

Important food sources
Vitamin B12 is found almost exclusively in animal foods, above all in liver and meat. Very small amounts of vitamin B12 are contained in foods that are produced by means of bacterial fermentation (e.g. sauerkraut). Here the vitamin is formed by the lactic acid bacteria.

Deficiency
A nutritional deficiency of vitamin B12 is extremely rare. For one thing, we require only very small amounts; for another, the human body has reserves of vitamin B12 on which one can draw for a long time, even on a diet lacking in vitamin B12. Only persons who live exclusively on plant foods for many years may possibly develop a vitamin B12 deficiency.

A wholly different reason for an insufficient supply of vitamin B12 can be a chronic inflammation of the gastric mucosa or the condition following (partial) removal of the stomach. A substance is formed in the gastric mucosa that binds with vitamin B12. The formation of this complex is prerequisite to the body’s utilization of the vitamin. If this factor is lacking because the gastric mucosa is missing or diseased, a vitamin B12 deficiency will eventually develop. This can lead to severe anaemia.


Folic acid

Functions in the body
Folic acid is essential above all for the regeneration and division of the body’s cells and is thus especially important for the formation of blood cells. Folic acid is particularly important in pregnancy: An insufficient supply during this period can lead to severe foetal anomalies or to miscarriages.

New scientific findings have shown in addition that a sufficient supply of folic acid reduces the risk of cardiac disease, above all of myocardial infarction.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 400 µg per day.

Important food sources
Folic acid is supplied by certain types of vegetables, above all leafy green vegetables (varieties of cabbage, spinach) and lettuce, whole-grain products, nuts, liver, milk and dairy products. Wheat germ and soybeans are particularly rich in folic acid.

Deficiency
The average intake of folic acid by the population is not as high as would be desirable. This is due not least to the fact that folic acid is a very sensitive vitamin and can easily be destroyed in storage or during the preparation of food.

Vegetables and lettuce should therefore be stored in the dark and for as short a time as possible and should be washed only briefly. Vegetables should preferably be steamed for only a short time, not cooked with a large amount of water, and not kept warm if possible.

Folic acid deficiency leads to, among other things, anaemia, digestive disorders and changes in the mucous membranes. The risk of myocardial infarction is increased, as is the danger of anomalies and miscarriage during pregnancy.


Niacin

Functions in the body
Niacin is necessary at numerous stages for a smoothly functioning metabolism.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 13–17 mg of niacin per day.

Important food sources
Meat, innards, fish, milk and eggs supply considerable amounts of niacin. Bread and baked goods, potatoes and coffee contribute substantially as well.

Deficiency
Niacin deficiency is practically unknown in this country.


Biotin

Functions in the body
Biotin is needed for many metabolic processes, among others, for the synthesis and biodegradation of fatty acids and in the metabolism of carbohydrates. It is important for the skin and hair.

Recommended intake
We know very little to date about how much biotin is actually needed by the body. It is thus difficult to recommend a specific intake. It is estimated that approximately 30–60 mg per day is adequate for an adult.

Important food sources
Liver, egg yolk, soybeans, nuts, oat flakes and wheat germ are particularly good sources of biotin.

Our intestinal bacteria also contribute quite considerably to our supply of biotin. They form biotin that can be utilized by the body.

Deficiency
Biotin deficiency is practically unknown.


Pantothenic acid

Functions in the body
Pantothenic acid is necessary at many stages for a smooth metabolic process, above all in the metabolism of fat and carbohydrates.

Recommended intake
We know very little to date about how much biotin is actually needed by the body. It is thus difficult to recommend a specific intake. It is estimated that about 6 mg of pantothenic acid per day is sufficient for an adult.

Important food sources
Pantothenic acid is found in practically all foods. Especially good sources are liver, meat, fish, eggs, whole-grain products and legumes.

Deficiency
A deficiency of pantothenic acid is practically never seen. The minimum requirement is apparently always met.


Vitamin A (retinol and beta-carotene)

Functions in the body
Among other things, vitamin A is important for the composition of our skin and mucous membranes. Moreover, it participates in growth processes and in our vision. Regarding the latter, it ensures that we can still see well even in twilight.

We can also absorb the preliminary stage of vitamin A, beta-carotene, which is then converted to vitamin A in the body. Approximately 1 mg of vitamin A is formed from 6 mg of beta-carotene.

Beta-carotene has effects of its own in the body, however. It has antioxidant characteristics; it intercepts dangerous free radicals and protects the cells, thus presumably working against the development of cancer.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 1 mg of vitamin A per day.

More specifically, it should be so-called retinol equivalents (RE). This means that we can absorb both vitamin A itself and its preliminary stage, beta-carotene. For example, if we take 0.5 mg of retinol and an additional 3 mg of beta-carotene (from which 0.5 mg retinol can be formed) we have a total of 1 mg RE. If more beta-carotene is supplied than the body needs at any given time for the formation of vitamin A, no further conversion takes place, and the beta-carotene then works as an antioxidant.

In order to simplify the process we generally speak only of vitamin A, but both vitamin A itself and beta-carotene are meant.

Important food sources
"Finished" vitamin A is found only in animal foods, with especially large amounts in liver, egg yolk and butter.

Beta-carotene, on the other hand, in found also in plant foods, particularly in yellow-orange fruits and vegetables (e.g. carrots, tomatoes, apricots) and in leafy green vegetables. More information can be found under Secondary Plant Substances.

Deficiency
A vitamin A deficiency leads to impaired vision in twilight and darkness, in severe cases to night blindness. In developing countries, where vitamin A deficiency is frequently very severe, it is a common cause of blindness.

Other symptoms of a vitamin A deficiency are damage to the skin and mucous membranes and growth disturbances.


Vitamin D (calciferols)

Functions in the body
With the help of vitamin D, the uptake of calcium from food is improved and calcium and phosphorus are stored in the bones. Thus it is important for bone formation and stability.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 5 µg of vitamin D per day.

Through the effect of sunlight on our skin, our body can usually synthesize a sufficient amount of vitamin D on its own. Even a few minutes a day in the sun are sufficient to produce vitamin D. For infants and young children, who must form a large amount of bony tissue, this self-synthesis is not sufficient, and they must take in extra vitamin D. Vitamin D supplied through the diet is important also for persons who, because of health or other problems, spend practically no time in the sun.

Important food sources
Vitamin D is found in only a few foods. Above all fatty fish (herring and mackerel), liver, margarine (enriched with vitamin D) and egg yolk contain appreciable amounts of vitamin D.

Deficiency
If infants or small children get too little vitamin D their bones lack the necessary solidity. Deformation of the bones and rickets are the result. Today, this is effectively prevented, for example by giving infants vitamin D tablets and baby food enriched with vitamin D. Therefore, rickets practically never occurs in our part of the world anymore.

Vitamin D deficiency in adulthood also leads to osteomalacia (softening of the bones), but this likewise occurs very rarely.


Vitamin E (tocopherols)

Functions in the body
Vitamin E is one of the most important protective systems in our body, guarding against attack by free radicals. It ensures mainly that polyunsaturated fatty acids (e.g. in cell membranes or in the blood) are not attacked and destroyed by these aggressive oxides. It thus contributes to the prevention of cancer, arteriosclerosis and ageing processes.

Recommended intake
According to the recommendations of the German Society for Nutrition, adults should take in approximately 15 mg per day.

Important food sources
The best sources of vitamin E are vegetable oils, above all germ oils, rapeseed oil and olive oil. Nuts and wheat germ are also good suppliers of vitamin E.

Deficiency
A clear deficiency of vitamin E is unknown in human beings. It should be assumed, however, that with a very low intake of vitamin E the effectiveness of one’s antioxidant protective system is limited. Protection against the diseases described is then hardly possible.


Vitamin K (phyllochinon)

Functions in the body
Vitamin K is needed for the formation of various factors that play a role in coagulation.

Recommended intake
We know very little to date about how much vitamin K is actually needed by the body. It is thus difficult to recommend a specific intake. It is estimated that 70–80 µg of vitamin K per day is sufficient for an adult.

Important food sources
Vitamin K is found in abundance in leafy green vegetables. In addition, milk and dairy products, meat, eggs and whole-grain products supply vitamin K.

Deficiency
A vitamin K deficiency leads to disturbances of coagulation. Normally, however, there are no supply bottlenecks, and vitamin K deficiency is extremely rare.

 



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