What is vitamin B12 ?
Vitamin B12, also called cobalamin, is one of the 8 vitamins of group B, It is one of the only water soluble vitamins that can be stored by the body, which allows the body to have some reserves!
Deficiencies and roles of vitamin B12 in the body
Covering your vitamin B12 needs is essential because this vitamin provides many functions within the body
Functioning of the nervous system
Vitamin B12 participates in balance and protection of the nervous system. Indeed, it is essential for the maintenance of the myelin sheath, an envelope protecting neurons. Thus a vitamin B12 deficiency can eventually lead to severe neurological disorders such as loss of feeling, tingling, numbness, difficulty walking, memory loss, or frequent mood changes.
Synthesis of red blood cells
In combination with iron and vitamin B9, vitamin B12 participates in the formation of red blood cells (red blood cells) and therefore contributes to optimal blood formation. A vitamin B12 deficiency is also responsible for a specific anemia called macrocytic anemia (meaning "large cell" in Greek) because it results in the formation of red blood cells larger than the norm, causing a chronic fatigue.
Vitamin B12 plays an essential role in the tissue formation and maintenance because it intervenes in the DNA synthesis and in the process of cell division. For example, vitamin B12 deficiency can manifest itself as altered skin quality and mucous membranes (redness, inflammation, psoriasis, eczema), hair and nails.
Vitamin B12 also plays an important role in the energy production, by participating like the majority of vitamins of group B in the metabolism of proteins, lipids and carbohydrates and therefore the normal functioning of the energy metabolism.
Vitamin B12 contributes to reduce cardiovascular risks because it helps to limit, with vitamin B9, the accumulation ofhomocyteine, an amino acid found in the blood toxic in excess. Indeed, an accumulation of homocysteine in the blood promotes the formation of atheromatous plaques, known to increase the risk of cardiovascular illnesses. Studies have also shown that vitamin B12 supplementation, associated with folic acid and vitamin B6, could help reduce the formation of lipid deposits on the arteries.
Populations at risk of deficiency and food supplements
Vitamin B12 deficiencies and the vegan diet
Vitamin B12 deficiency can be the result of lack of food intake, that is to say that the diet does not cover the needs of the body. Vitamin B12 being provided exclusively by food of animal origin, people having excluded products of animal origin such as vegan / vegan are populations very exposed to the risk of deficiencies. Thus, due to the potentially serious disorders that can be induced by a vitamin B12 deficiency, supplementation is strongly recommended by for people who have excluded animal products from their diet. It is so strongly advised for people following a vegan or vegan diet to supplement with vitamin B12 thanks to food supplements or industrially fortified foods.
Also, although less restrictive, the diet vegetarian may be low in vitamin B12. This is why it is also sometimes recommended for vegetarians to use food supplements if their diet is not balanced, in order to prevent the risk of deficiency.
Vitamin B12 deficiencies and pregnant women
- vitamin B12 requirements in pregnant women are increased. Thus, during gestation, it is essential for all pregnant women to ensure their vitamin B12 needs are met because this one is essential to the good health of the mother but also to the development of the fetus. A vitamin B12 deficiency during pregnancy can (like a vitamin B9 deficiency) lead to severe complications for the child, such as risk of miscarriages or neurological damage. It is then all the more important to watch out for the risk of vitamin B12 deficiency in pregnant vegetarians or vegans.
Vitamin B12 deficiency and the elderly
Older people have a double risk of vitamin B12 deficiency. On the one hand, with age, their body has more and more difficulty in assimilate sufficient amounts of micronutrients (vitamins, minerals, trace elements). On the other hand, we frequently observe age-related changes in eating behavior, including a reduced food intake or a exclusion of animal products, which may increase the risk of undernutrition and therefore of vitamin B12 deficiency.
Vitamin B12 deficiencies and malabsorption disorders in the event of pathology and / or medical treatment
In case of chronic gastrointestinal disease such as chronic gastritis, Biermer's disease or Crohn's disease, the assimilation of vitamin B12 is strongly disturbed. This is why vitamin B12 supplementation is very often recommended in order to prevent any risk of deficiency. Similarly, people who have suffered partial ablations of the digestive system (stomach or intestine) will most of the time need to supplement vitamin B12 throughout their life. Also, some long-term medical treatments can alter the assimilation of vitamin B12. This is for example the case for drugs against gastric acidity, the contraceptive pill or oral anti-diabetics. In the event of prolonged treatment, it may therefore be beneficial to take food supplements containing vitamin B12.
Daily vitamin B12 requirements
The European Union recommends a daily intake (RDA) of vitamin B12 of 2,5µg for an adult. In France, since 2017, the intakes recommended by theANSES (National Agency for Food, Environmental and Occupational Health Safety,) range from 0,8 µg per day for young children, in 4 µg per day for adults.
Food sources of vitamin B12
In nature, vitamin B12 is synthesized by bacteria living in the soil or in the digestive tract of mammals and herbivores. Thus, it is one of the only vitamins of the B group that can be produced by our body, in particular by our intestinal microbiota.
However, the majority of bacteria producing vitamin B12 in significant amounts are present in our colon, located downstream of the ileum (terminal part of the small intestine), where vitamin B12 is absorbed. Thus, our organism not being able to synthesize and absorb it in sufficient quantity vitamin B12, must must be provided daily through food.
Unlike other vitamins, vitamin B12 has the particularity of being contained only in products of animal origin, but in no product of the vegetable kingdom. Thus, the best sources of vitamin B12 are:
- the liver (75µg / 100g);
- organ meats (10µg / 100g);
- red meat (7µg / 100g);
- shellfish (15µg / 100g);
- mackerel (5µg / 100g);
- eggs (1,7µg);
- dairy products (0,5µg / 100g).
Finally, some algues (nori, chlorella) or cyanobacteria (spirulina) are sometimes touted as reliable dietary sources of vitamin B12. However, although they may contain some, studies have shown that the form of vitamin B12 contained in these foods is hardly absorbed by the human bodyOr disrupt the assimilation of vitamin B12.
Side effects and contraindications of vitamin B12
Scientific literature does not report side effects linked to a significant supplementation of vitamin B12, even at very high doses because the excess is filtered by the kidneys and eliminated through the urine.
Anecdote : Origin of vitamin B12
It was in the 12th century that the first research on vitamin B1948 saw the light of day. It was identified by showing that the administration of liver extracts made it possible to correct certain anemias. She then succeeded in being isolated in XNUMX thanks to the work of an American biochemist: Karl Folker.