Vitamin B12 (cobalamin) is a water-soluble vitamin that – just like other vitamins – cannot be produced by the body itself, but must be absorbed through foods such as herring or liver. Vitamin B12 is particularly important for our nervous system, but also has a protective effect on our cardiovascular system. A deficiency of vitamin B12 occurs only rarely in Europe, only vegans who do not eat animal foods have an increased risk.
How vitamin B12 works
Although our body needs only small amounts of vitamin B12, the vitamin is nevertheless involved in many important processes in the organism. Thus, among other things, it influences cell growth as well as cell division and is needed for the formation of erythrocytes. In addition, vitamin B12 is also of crucial importance for our nervous system, as it participates in the formation of the myelin sheath, which coats the nerve fibers. Vitamin B12 is also important for our brain. Scientists suspect that individuals with a vitamin B12 deficiency have a significantly increased risk of developing dementia later in life. Likewise, these individuals are said to be more likely to experience brain mass loss. Finally, vitamin B12 is also said to have a protective effect on the cardiovascular system: it converts the amino acid homocysteine, which can have a harmful effect on the heart and circulation, into the harmless amino acid methionine. Through this conversion, vitamin B12 prevents diseases such as arteriosclerosis.
Vitamin B12: Daily requirement
The daily dose of vitamin B12 is only four micrograms, which is significantly lower than other vitamins. In pregnant and breastfeeding women, the requirement is somewhat higher, amounting to about 4.5 and 5.5 micrograms, respectively. The daily requirement of vitamin B12 can be met, for example, by eating one of the following foods:
- 7 grams of liver
- 33 grams herring
- 120 grams of pollock
- 135 grams of beef
- 135 grams salmon
- 200 grams of cheese
- 4 eggs
- 670 milliliters of whole milk
Vitamin B12 deficiency in vegetarians and vegans.
A look at the list of foods that have a high vitamin B12 content makes it clear that vitamin B12 in quantities worth mentioning is found only in animal foods. Therefore, vegetarians, but especially vegans, must be careful not to become deficient in vitamin B12. If there is a risk of a deficiency, they can prevent it by taking vitamin B12 tablets. In addition to animal foods, very small amounts of vitamin B12 are also contained in plant foods that are bacterially fermented. Sauerkraut, for example, is one of these foods. However, whether the body can adequately utilize this form of the vitamin is controversial.
Vitamin B12 deficiency
Because vitamin B12 has a very long half-life, vitamin B12 deficiency develops very slowly. If the supply of vitamin B12 is stopped completely, the body can still draw on the reserves created in the liver for about two to three years, and only then does the deficiency become noticeable. In addition to the liver, vitamin B12 is also stored in the brain, heart and skeletal muscles. The cause of a vitamin B12 deficiency can be, on the one hand, that the body is supplied with too little vitamin B12 through the diet. However, it is much more often the case that the absorption capacity in the gastrointestinal tract is disturbed. Vitamins can normally be absorbed directly into the body via the intestines, but in the case of vitamin B12, a transport protein – the so-called intrinsic factor – is required. Often, the production of this intrinsic factor by the stomach cells is disturbed in older people, as they are particularly likely to have gastric mucosal atrophy. In addition, however, production of the factor is also negatively affected by chronic gastritis, drugs such as omeprazole that inhibit gastric acid production, and severe inflammation of the intestines such as Crohn’s disease.
Symptoms of vitamin B12 deficiency
If too little vitamin B12 is consumed or if the amount present cannot be utilized, this can lead to anemia, which is also known as pernicious anemia in professional circles. Anemia is accompanied by symptoms such as pallor, impaired concentration, and fatigue.In addition, vitamin B12 deficiency can also cause sensory disturbances in the feet and hands. These insensations are due to disturbances in the central nervous system caused by the vitamin B12 deficiency. The same applies to occurring memory disorders, which can develop into dementia. Other symptoms that can be caused by vitamin B12 deficiency are:
- Loss of appetite and weight loss
- Gastrointestinal problems such as diarrhea or constipation
- Tongue burning
- Dizziness
- Increased susceptibility to infections
- Dysfunction in the spinal cord (funicular myelosis).
Vitamin B12 overdose
An overdose of vitamin B12 is not possible in normal cases, because vitamin B12 is water-soluble and excess vitamin B12 is simply excreted by the kidneys. If vitamin B12 is used for therapeutic purposes and administered by injection, an overdose is possible, but it usually remains without consequences. Only in rare cases can local allergic reactions and acne-like symptoms occur as a result of the overdose. One study suggests that long-term use of high-dose vitamin B12 preparations could possibly increase the risk of lung cancer in men. However, further research on this topic is still pending. The German Federal Institute for Risk Assessment (BfR) recommends not exceeding a daily intake of 25 micrograms when taking vitamin B12 in the form of dietary supplements.
