What is B12 and why do we need it?

Vitamin B12 is one of the eight b vitamins from the Vitamin B Complex. B12 (cobalamin) is a vitamin, i.e. a chemical compound that we have to take in from the outside with our food. In contrast to carbohydrates, fats and proteins, vitamins do not serve to generate energy in the body, but rather fulfill other important functions in the metabolism. Vitamin B12, for example, is essential for DNA synthesis and helps break down the harmful homocysteine.

Animals, including humans, cannot produce B12 themselves. It is only produced by microorganisms such as bacteria and some unicellular algae. Bacteria that produce B12 can be found on many plant roots of wild plants. Likewise, on wild plants and on plants that have been fertilized with animal manure, there are often residues of animal feces that contain intestinal bacteria that also produce B12. Herbivores (plant eaters) take their necessary B12 dose through these parts of the plant. Carnivores (meat eaters) and omnivores (omnivores) in turn consume the plant eaters and thus get their B12. Bacteria on plants can also cause serious diseases, so we humans wash our food thoroughly, but our plant food no longer contains B12 and we have to supplement it,

Biochemical details

B12 is an important component of two enzymes in the human body. Enzymes allow individual chemical reactions in the metabolism to take place in a controlled manner, they are said to catalyze them. Many enzymes use small auxiliary molecules called cofactors for this purpose. B12 is a cofactor for the enzymes methylmalonyl-CoA mutase and methionine synthase.

The enzyme methylmalononyl-CoA mutase plays a role in the breakdown of fatty acids. It converts methylmalonyl-CoA to succinyl-CoA. If B12 is missing, this reaction cannot take place and methylmalonyl-CoA is not broken down as intended. Instead, it creates methylmalonic acid (MMA), which accumulates in the body. This is excreted in the urine. Therefore, an indicator of vitamin B12 deficiency is too much MMA in the blood serum and urine. However, too high MMA levels can also reflect inadequate kidney function. The MMA value is therefore a helpful but not the only sufficient indicator of a vitamin B12 deficiency .

The enzyme methionine synthase converts the amino acid homocysteine ​​into the amino acid methionine. This is a reaction that is very important in the build-up and breakdown of various chemical compounds in the body, as methionine is required for numerous other reactions. If there is a deficiency in B12, the methionine synthase reaction cannot take place and homocysteine ​​builds up in the body. The homocysteine ​​level in the blood can therefore also be an important indicator of a vitamin B12 deficiency . Since the methionine synthase reaction is centrally anchored in the metabolism, other deficiencies also lead to an increase in the homocysteine ​​level: especially deficiency in folic acid (vitamin B9) (unlikely in vegans), pyridoxine (vitamin B6) and riboflavin.