Vitamin B12, also known by its chemical name cobalamin, plays a major role in various metabolic processes. For example, the vitamin is involved in the breakdown of certain fatty acids and also supports blood formation by converting the vitamin folic acid into its biologically active form. Furthermore, vitamin B12 supports cell division and is involved in the smooth functioning of the nervous system. In the case of cobalamin, it is not a single vitamin either. Instead, the term refers to a group of compounds with the same chemical structure. These are referred to as cobalamins. Vitamin B12 cannot be produced by the human or animal organism itself, nor does it occur in plant sources. Instead, the vitamin is produced by microorganisms, especially bacteria. The microorganisms in question live as symbionts in the digestive tract of living organisms. In and on plants, on the other hand, the vitamin occurs only in traces. The need for vitamin B12 can only be met by humans through the consumption of meat. Small amounts of cobalamin are produced in the intestine, but in the wrong place. Vitamin B12 is absorbed mainly through the large intestine. However, the producing bacteria are located in the terminal ileum, where the cobalamin cannot be absorbed and is therefore excreted unused. The situation is different in pure herbivores, because in ruminants the vitamin is formed in the forestomach. Other herbivores reabsorb cobalamin via the large intestine, where the producing microorganisms live in symbiosis with the herbivore host. However, this assumption does not apply to omnivores such as humans, pigs, and dogs.
Vitamin B12 requirements and deficiency symptoms
The German Nutrition Society (DGE) recommends a daily dose of three micrograms per day for adolescents 15 years and older as well as adults. Pregnant and breastfeeding women have an increased requirement of 3.5 to four micrograms daily, as they supply their child with the vitamin via the bloodstream or breast milk. Vitamin B12 is found primarily in meat, fish and eggs, and in small amounts in milk and dairy products. Very small traces are found in fermented plant products, for example sauerkraut, fermented soy products (miso, natto) and certain algae (especially spirulina and nori algae). A vitamin B12 deficiency is rather rare in Germany, but occurs relatively frequently in people who eat a vegan or vegetarian diet. Patients with certain intestinal diseases such as Crohn’s disease or chronic gastritis are also at risk. Some people also lack the relevant intrinsic factor that enables the absorption of cobalamin in the first place. Vegans and vegetarians, but also patients with the above-mentioned intestinal diseases, should therefore take B12 in the form of tablets or capsules. Regular intake of the supplements prevents a deficiency with its serious consequences. A deficiency may only become apparent after years, since cobalamin is stored in the liver and kidneys. The consequence of a vitamin B12 deficiency is primarily a form of anemia, which is accompanied by pallor and extreme fatigue, among other symptoms. Characteristics such as tingling or burning of the tongue and feelings of numbness are also typical. So far, no negative effects have been reported as a result of cobalamin overdose, since the body automatically reduces its intake in the event of increased intake.