What is B12?
Vitamin B12, also known as cobalamin, is an essential water-soluble vitamin that plays a crucial role in the human body. It is essential for the formation of red blood cells, the synthesis of DNA and the functioning of the nervous system. Without sufficient vitamin B12, serious health problems can occur, including anaemia, neurological disorders and impaired cognitive function.
This vitamin is mainly found in animal products such as meat, fish, eggs and dairy products. Therefore, vegans and vegetarians in particular are at a higher risk of vitamin B12 deficiency, as their diets often contain little to no natural sources of this vitamin. In such cases, the intake of fortified foods or food supplements may be necessary to cover the requirement.
The human body can store vitamin B12 in the liver, which means that it can take months or even years for a deficiency to develop if intake suddenly stops. Symptoms of deficiency can include fatigue, weakness, constipation, loss of appetite and weight loss. If left untreated in the long term, a vitamin B12 deficiency can cause irreversible damage, particularly to the nervous system.
Because of its importance to health and well-being, it is important to ensure an adequate intake of vitamin B12, whether through a balanced diet or supplementation, especially for vulnerable populations.
How is B12 obtained?
Vitamin B12 is mainly produced in nature by microorganisms such as certain bacteria, archaea and algae. These microorganisms synthesise vitamin B12 through complex biochemical processes. There are several methods to obtain vitamin B12 for food supplements and fortified foods:
1. fermentation: the most commonly used method for the industrial production of vitamin B12 is fermentation. Specific bacteria such as Propionibacterium shermanii or Pseudomonas denitrificans are cultivated in large fermenters. These bacteria produce vitamin B12, which is then extracted and purified.
2. biotechnological processes: Genetic modifications can be used to make microorganisms more efficient at producing higher amounts of vitamin B12. These biotechnological improvements optimise the fermentation processes and increase the yield.
3. isolation from animal sources: Since animals, especially ruminants such as cattle and sheep, store vitamin B12 in their organs, it can also be obtained from animal liver extracts. However, this method is less common due to ethical concerns and inefficient yields compared to microbial fermentation.
4. fortification and supplementation: In the food industry, vitamin B12 is often artificially added to increase nutrient levels. This is particularly common in vegan and vegetarian products such as plant-based milk alternatives, breakfast cereals and food supplements.
Overall, fermentation by microorganisms is the most efficient and widely used method of producing vitamin B12 for human consumption.
How does B12 work?
Vitamin B12, also known as cobalamin, plays a central role in many physiological processes of the human body. This water-soluble vitamin is essential for the formation of red blood cells, DNA synthesis and the functioning of the nervous system. The mode of action of vitamin B12 in the body comprises several important biochemical and physiological functions, which are described in detail below.
Synthesis of red blood cells
One of the best-known functions of vitamin B12 is its role in the production of red blood cells. Vitamin B12 acts as a co-factor in the synthesis of DNA in bone marrow cells. It supports the maturation of these cells into fully functional red blood cells. Without sufficient vitamin B12, cell division and maturation can be disrupted, resulting in megaloblasts - abnormal, large red blood cells that transport oxygen inefficiently. This can cause a form of anaemia known as megaloblastic anaemia, manifested by symptoms such as fatigue, weakness and pale skin.
Nervous system and myelin synthesis
Vitamin B12 is crucial for the health of the nervous system. It is involved in the synthesis of myelin, a fatty substance that coats and protects nerve fibres. Myelin enables the fast and efficient transmission of nerve impulses. A vitamin B12 deficiency can lead to demyelination, which impairs nerve function. This can lead to neurological symptoms such as numbness, tingling in the hands and feet, balance problems and, in severe cases, permanent nerve damage. Cognitive functions such as memory and concentration can also be affected.
DNA synthesis and cell division
Vitamin B12 plays a key role in DNA synthesis and cell division. It acts as a coenzyme in the conversion of homocysteine to methionine, an important step in the methylation cycle. This cycle is crucial for the production of DNA and RNA, the genetic materials necessary for cell growth and repair. A deficiency of vitamin B12 can impair DNA synthesis, which can lead to reduced cell division and impaired cell function.
Homocysteine metabolism
Another important aspect of the effect of vitamin B12 is its role in homocysteine metabolism. Homocysteine is an amino acid which, in high concentrations in the blood, is associated with an increased risk of cardiovascular disease. Vitamin B12 helps to convert homocysteine into methionine, thereby lowering the concentrations of homocysteine in the blood. This conversion is not only important for heart health, but also for the synthesis of S-adenosylmethionine (SAM), a molecule involved in many methylation reactions in the body, including the regulation of gene expression and neurotransmitters.
Energy production
Vitamin B12 also plays a role in energy metabolism. It is involved in the conversion of fats and proteins into energy. In particular, it is a coenzyme for methylmalonyl-CoA mutase, an enzyme necessary for the breakdown of certain amino acids and fatty acids. A lack of vitamin B12 can lead to a loss of energy and general fatigue, as the efficient conversion of these nutrients is impaired.
Immune system
Although the direct effect of vitamin B12 on the immune system is less well understood, there is evidence that a deficiency can impair immune function. Vitamin B12 is necessary for the production and maturation of white blood cells, which play a key role in defence against infection.
Conclusion
To summarise, vitamin B12 is a vital vitamin that plays a central role in numerous biological processes. Its functions range from supporting blood cell formation and maintaining a healthy nervous system to DNA synthesis and energy metabolism. Adequate vitamin B12 levels are therefore essential for maintaining general health and well-being. A deficiency of this important nutrient can have serious health consequences, which is why an adequate supply should be ensured through food or, if necessary, supplements.
How does B12 differ from other active substances?
Vitamin B12 differs from other bioactive substances and other B vitamins in several key ways. These differences include its chemical structure, its biological function, its source, absorption mechanisms and its storage capacity in the human body. A detailed analysis of these differences is presented below.
Chemical structure
Vitamin B12, also known as cobalamin, has a unique chemical structure compared to other vitamins and bioactive substances. It contains a central cobalt atom embedded in a corrin ring. This structure is more complex than that of most other vitamins. Other B vitamins, such as thiamine (B1), riboflavin (B2) and niacin (B3), have less complicated molecular structures without metallic components.
Biological functions
The biological functions of vitamin B12 differ considerably from other B vitamins and bioactive substances. In particular, vitamin B12 is crucial for DNA synthesis, the production of myelin and the conversion of homocysteine into methionine. Other B vitamins have their own specific functions:
Vitamin B1 (thiamine): Supports energy production by converting carbohydrates into glucose.
Vitamin B2 (riboflavin): Participates in energy metabolism and serves as an antioxidant.
Vitamin B3 (niacin): Plays a role in the metabolism of fats, proteins and carbohydrates.
Vitamin B6 (pyridoxine): Important for amino acid metabolism and the synthesis of neurotransmitters.
Vitamin B9 (folate): Essential for DNA synthesis and cell division.
Sources and absorption
Vitamin B12 is mainly produced by microorganisms such as certain bacteria, archaea and algae. It occurs naturally in significant quantities almost exclusively in animal products. Vegetarians and vegans must therefore resort to fortified foods or food supplements. Other B vitamins are widely available in both plant and animal foods, which facilitates their absorption from a normal diet.
The absorption of vitamin B12 is a complex process that requires intrinsic factors in the stomach. The intrinsic factor binds to vitamin B12 and enables its absorption in the ileum, a part of the small intestine. Without the intrinsic factor, vitamin B12 cannot be absorbed effectively, which can lead to a deficiency. In contrast, other B vitamins are mainly absorbed by simple diffusion or specific transporters in the small intestine without the need for an intrinsic factor.
Storage capacity
A notable difference between vitamin B12 and other B vitamins is the body's ability to store large amounts of vitamin B12 in the liver. Other B vitamins, especially water-soluble vitamins such as vitamins B1, B2, B3, B6 and B9, are only stored in small amounts in the body.
Symptoms of deficiency
The symptoms of a vitamin B12 deficiency differ from those of a deficiency of other B vitamins. A vitamin B12 deficiency can lead to megaloblastic anaemia, neurological disorders and cognitive impairment. A deficiency of other B vitamins shows different clinical pictures:
Vitamin B1 deficiency: beriberi, Wernicke-Korsakoff syndrome.
VitaminB2 deficiency: ariboflavinosis, oral rhagades, skin inflammation.
VitaminB3 deficiency: pellagra, characterised by dermatitis, diarrhoea and dementia.
VitaminB6 deficiency: anaemia, skin inflammation, depression.
Vitamin B9 deficiency: megaloblastic anaemia, neural tube defects in foetuses.
Interactions and synergies
Vitamin B12 interacts synergistically with other B vitamins, in particular with folate (vitamin B9). Both vitamins are involved in the methionine synthase reaction, which converts homocysteine into methionine. A deficiency of either of these vitamins can lead to an increase in homocysteine levels, which is a risk factor for cardiovascular disease. Other B vitamins also have synergistic relationships, such as B6, B12 and folate working together to metabolise homocysteine.
Conclusion
Vitamin B12 stands out from other B vitamins and bioactive substances due to its unique chemical structure, specialised biological functions, specific sources, complex absorption mechanisms and remarkable storage capacity. These differences emphasise the need for a targeted and adequate intake of vitamin B12, especially for individuals with limited access to animal products. Understanding these differences helps to appreciate the importance of vitamin B12 in the context of a balanced diet and overall health.
