Vitamin-B12-Supplementierung: Cyanocobalamin vs. Methylcobalamin

Vitamin B12 is involved in important metabolic processes in the body - including the breakdown of amino and fatty acids. The vitamin also plays a role in blood formation and cell division. An adequate supply of vitamin B12 is therefore essential for your health. Some life situations (e.g. senior citizens) or certain dietary habits (e.g. vegans) require consistent vitamin B12 supplementation.

1. You should know these forms of vitamin B12
2. Methyl-, adenosyl- and hydroxocobalamin: the natural forms
3. Cyanocobalamin: synthetically produced vitamin B12
4. Cyanocobalamin vs. methylcobalamin
5. Other disadvantages of cyanocobalamin
6. Positive effects of methylcobalamin on health

You should know these forms of vitamin B12

Methyl-, adenosyl- and hydroxocobalamin: the natural forms

Vitamin B12 is also known as cobalamin. Cobalamin is found in our body and food in various forms. Methylcobalamin and adenosylcobalamin are known as the active forms of the vitamin, as they act as coenzymes in important metabolic reactions. Like hydroxocobalamin, both forms are absorbed through food. Vitamin B12 is mainly found in animal foods. However, it is actually produced by microorganisms, which is why it is also found in fermented foods such as sauerkraut or tempeh. However, the quantities contained are so small that they are not suitable for covering the daily requirement. Vegetarians and vegans should therefore be sure to take the vitamin via vegan food supplements.

You can find out more about Vitamin B12 with a vegan diet in our Blog.

Cyanocobalamin: synthetically produced vitamin B12

A fourth form of cobalamin is also frequently used in supplements - cyanocobalamin. Although this is not an active form of vitamin B12, it can be converted into it in the body. It is also quite stable and easy to produce synthetically.

However, there are some disadvantages, which is why cyanocobalamin is being used less and less in food supplements. As the absorption of vitamin B12 via the intestine is limited, the vitamin is usually injected in high doses in the event of an acute deficiency. If large amounts of cyanocobalamin are ingested, some of it is excreted quite quickly via the urine. Cyanocobalamin is therefore not suitable in the case of a deficiency or as a depot dose for several months. Hydroxocobalamin is more commonly used for intramuscular injections. However, hydroxocobalamin can cause side effects such as red discolouration of the skin or urine and gastrointestinal complaints.

There are now more and more vitamin B12 supplements containing methylcobalamin - the active form of the vitamin. This is much better absorbed and utilised by the body than cyanocobalamin, which must first be converted into the active form. What few people know: Some 10-15% of the population suffer from an enzyme defect that prevents this conversion step. Cyanocobalamin can therefore not be converted into the active forms. Supplementation with this synthetic vitamin B12 is therefore not suitable for everyone.

Other disadvantages of cyanocobalamin

Cyanocobalamin has also fallen into disrepute for another reason. As the name suggests, it is made up of cobalamin and a cyano group. This can be split off in the body and converted into toxic cyanide (hydrogen cyanide). Although the quantities produced are very small and not dangerous, they can have negative effects in people with high cyanide exposure (e.g. smokers). In contrast, methylcobalamin is considered safe. Side effects as with hydroxocobalamin do not occur with supplementation.

Positive effects of methylcobalamin on health

There is also study data that suggests that methylcobalamin has further positive effects on health. In animal experiments, it was able to increase the survival rates of mice suffering from cancer. Methylcobalamin also has a favourable effect on sleep disorders - presumably due to its involvement in the production of the sleep hormone melatonin. These benefits have not been shown for cyanocobalamin.

• A. G. Freemann et al. Cyanocobalamin-a case for withdrawal: discussion paper. Journal of the Royal Society of Medicine Volume 1992; 85.
• S. Akkus Arslan et al. Cobalamins and Methylcobalamin: Coenzymes of Vitamin B12. J. Pharm. Sci. 2013;38(3):151-157.
• S. Tsao et al. Influence of Cobalamin on the Survival of Mice Bearing Ascites Tumour. Pathobiology 1993;61:104-108.
• I. Masayuki et al. Methylcobalamin amplifies melatonin-induced circadian phase shifts by facilitation of melatonin synthesis in the rat pineal gland. Brain Research 1998; 795:1-2(8): 8-104.