What is it?
Isolated in 1948 by Karl Folker and his team during studies on pernicious anemia, vitamin B12 is one of the eight B-group vitamins. Also called cobalamin, it is water-soluble – that is, soluble in water.
It plays an essential role in protein synthesis, the process of cell division, the construction of DNA, the functioning of the nervous system and in the formation of blood components – red blood cells.
The vitamin B12 present in the body is primarily introduced through diet. Only animal-derived foods and supplementation – dietary supplements, can ensure vitamin B12 stores.
Vegetarians and vegans are therefore advised to take supplements to avoid vitamin B12 deficiencies.
The absorption of this element occurs at the digestive level. Indeed, the process requires the presence of gastric acid and a factor – called intrinsic factor, which is produced by the lining of the stomach.
The body stores vitamin B12 in the liver, brain, pancreas and heart. The body’s reserves are approximately 2 to 3 mg of the vitamin.
Daily requirements are the lowest of all nutrients (about 0.1 to 1 µg/day). So much so that it usually takes several years, around 5 to 6 years, to notice the first signs of vitamin B12 deficiency.
The benefits of vitamin B12
Vitamin B12 performs several functions in the body. It notably helps to:
- Maintenir la vitalité en intervenant dans le métabolisme du glucose (elle permet de convertir les glucides en glucose). Le glucose est le carburant du corps, par excellence. Il permet au cerveau de fonctionner efficacement.
- Elle est utilisée dans le cadre de la formation des globules rouges et plus particulièrement de l’hémoglobine. Une carence en vitamine B12 entraîne donc l’apparition d’une anémie. Cette affection limite l’apport d’oxygène et de fer à l’ensemble des organes du corps, d’où l’apparition d’une sensation de fatigue et de ralentissement.
- Elle permet de maintenir l’équilibre nerveux. La vitamine B12 constitue un des éléments permettant de former la gaine de myéline (substance blanche qui protège les nerfs). Elle est indispensable pour assurer un bon fonctionnement cérébral. Dans ce cadre, elle permet de limiter les troubles neurologiques et de prévenir certaines maladies neuro-dégénératives.
- Elle participe à la fabrication d’acide nucléique (qui intervient dans le cadre de la synthèse d’ADN et d’ARN)
- Elle est efficace dans la synthèse d’acide folique, élément indispensable lors de la grossesse, pendant les trois premiers mois.
- Elle permet de limiter les troubles de l’humeur et les manifestations du stress.
- Elle permet de préserver la fonction cardiaque.
Symptoms of deficiency
A vitamin B12 deficiency can occur in cases of intestinal malabsorption, digestive disorders (reduced gastric acidity), or in people who consume little or no animal meat (vegetarians and vegans).
People who have undergone a partial gastrectomy (surgical removal of part of the stomach) may also be at risk of vitamin B12 deficiency.
Indeed, this element is not synthesized by the body and comes primarily from animal products. However, since daily requirements are relatively low, it takes several years before the first symptoms of deficiency appear:
- Anémie microcytaire (les globules rouges formés sont trop petits)
- Grande fatigue
- Troubles de la mémoire
- Etat dépressif
- Troubles du sommeil/stress
- Perte d’appétit
- Troubles musculaires
Pernicious anemia is a disease that occurs when the body cannot absorb vitamin B12.
In fact, in this situation, the body does not synthesize intrinsic factor, which is essential for the absorption of vitamin B12. It therefore cannot form reserves and store this vitamin.
Note: some medications have an inhibitory effect on the absorption of vitamin B12. This is the case with metformin, a drug used in the treatment of type 2 diabetes. Some medications used to reduce the stomach’s acidic secretions limit the absorption of vitamin B12.
Don’t hesitate to discuss this with your doctor if they prescribe these medications to consider possible alternatives.
Recommended nutritional intakes
Considering the large stores that the body maintains (the body retains vitamin B12 reserves that allow it to function independently for 3 to 5 years), the recommended dietary intakes are not very high.
- Bébés de 0 à 6 mois : 0,4 µg/jour
- Bébés de 7 à 12 mois : 0,5 µg/jour
- Enfants de un an à 3 ans : 0,8 µg/jour
- Enfants de 4 à 6 ans : 1,1 µg/jour
- Enfants de 7 à 9 ans : 1,4 µg/jour
- Enfants de 10 à 13 ans : 1,8 µg/jour
- A partir de 14 ans : 2,5 µg/jour
- Femmes enceintes : 2,6 µg/jour
- Femmes qui allaitent : 2,8 µg/jour
The body partially absorbs the amounts of vitamin B12 provided by the diet. That’s why daily intakes are recommended.
Top 5 foods containing vitamin B12
To enjoy the benefits of vitamin B12, it’s essential to know which foods contain it.
Foods rich in vitamin B12 are animal-derived products. Vegetarians and vegans do not consume them. To ensure adequate vitamin B12 intake, they must take dietary supplements daily. Here is a selection of 5 foods containing vitamin B12.
1. Meats and offal
Red meats (beef) and offal (veal liver, lamb liver) are rich in vitamin B12. Red meat is fairly fatty, so it is best consumed in moderation.
To prepare diet-friendly dishes, it’s useful to assemble a variety of skewers, bake them in the oven, and serve the dish with fresh boiled or steamed vegetables (green beans, broccoli), accompanied by a portion of potatoes or whole grains (pasta, rice).
2. Seafood
The advantage of fruits is that they are low in calories. Therefore, they are foods that can be eaten in large quantities. Vitamin B12 is found in raw oysters, shrimp, clams or periwinkles.
These seafood items can be served as a starter, with a tomato or lemon sauce. To limit calories, it’s best to avoid mayonnaise. You can also make it yourself using reduced-fat products.
Oysters, shrimp and clams go wonderfully with pasta dishes when they are skillfully prepared.
3. Fatty fish
Fatty fish, such as mackerel, herring, cod, sardines or haddock, are among the foods that are sources of vitamin B12. They do indeed contain many nutrients that are good for health, such as omega-3 fatty acids and vitamin D.
Remember that it’s preferable to favor oven baking, cooking en papillote, or grilling rather than pan-frying, which requires adding fats. Simply round out your dishes with vegetables and starchy foods, the foundation of balanced meals.
4. Eggs
Eggs are also foods enriched with vitamin B12. Be aware that while the egg white is rich in protein, the yolk contains cholesterol. So you should be careful not to consume too many eggs over the course of the week.
Don’t hesitate to eat eggs for breakfast (scrambled eggs, hard-boiled eggs, or soft-boiled eggs) to sustain you throughout the day! Eggs are also an excellent choice for evening meals. Enjoy them in omelets with a soup, a salad, or vegetables served with potatoes.
5. Dairy products
Rich in calcium, vitamin D, tryptophan – a precursor of melatonin, the sleep hormone, dairy products contain vitamin B12. That’s why you should consider adding plain yogurts, Emmental, Gouda, or Camembert to your menus.
Eating a portion of cheese at lunch, with a fruit for dessert and a yogurt in the evening after dinner makes a good routine. Yogurt can also be a good snack to have about an hour before bedtime to enjoy a good night’s sleep.
Risks, side effects and vitamin B12 overdose
As we stated earlier, the body has significant stores of vitamin B12 and absorbs only part of the daily intake. Cases of overdose are therefore extremely rare. There is no established maximum dose, and attention should be focused on the possibility of deficiencies rather than on vitamin B12 overdosing.
