Vitamin B12, or cobalamin, is essential in several physiological processes, such as the formation of red blood cells, so much so that is best known for being anti-anemic. In addition, it is an essential vitamin for having a healthy and well-functioning nervous system.
In fact, your body is not able to synthesize vitamin B12, but it must necessarily take it with food. Those who do not eat meat or those who follow a vegan diet could suffer from a vitamin B12 deficiency.

Vitamin B12: what it is
Vitamin B12 owes its name to the presence of a Cobalt ion, while the isolated form takes the name of cyanocobalamin due to the addition of a cyanide ion.
This form, mostly extracted from natural sources and added to fortify many foods, is quickly converted within the body to the natural form for easy absorption.
It was discovered during anemia studies and first isolated in the liver. Understanding its particular chemical conformation earned British crystallographer Dorothy Hodgkin the Nobel Prize in 1964.

Vitamin B12: benefits and properties
The main biochemical role of vitamin B12 is to mediate the replication of DNA and RNA (together with folate), making cell renewal possible. It also assists in the isomerization reactions in the metabolism of many molecules. Hence, this type of chemical reactions is important in the development and production of energy.
In fact, it converts this amino acid, which can cause cardiovascular damage, into methionine, reducing the risk of heart attack.
Furthermore, it is important for central nervous system functions and for the synthesis of dopamine and noradrenaline.

The daily need for vitamin B12
The recommended dosage of vitamin B12 intake for adults is 2.4μg / day.
This value is recommended for both men and women, while in pregnancy it rises to 2.6μg / day and in lactation to 2.8μg / day to ensure an optimal concentration of this vitamin in breast milk.

Foods richer in vitamin B12
The vitamin B12 is synthesized in nature only by microorganisms and is virtually absent in plant sources, except by way of microorganisms that populate the surface (for example, is found in grains for breakfast, with have only 1μg / 100g), while animal sources are richer.
Being synthesized also in part from algae, we find small amounts of it in supplements or in fortified foods used by vegans to supplement their diet.
In 100 grams of product, you will find:
Liver (23 mcg / 100g).
Blue Fish (3 mcg / 100g).
Herring (13 mcg / 100g).
Salmon (16 mcg / 100g).
Eggs (7 mcg / 100g in the yolk).
Beef and Lamb (2 mcg / 100g).
Milk and derivatives (2mcg / 100g).

Vitamin B12: risks of deficiency and how to avoid it
To date, B12 deficiencies in industrialized countries are quite rare. However, particularly at risk are:
Elderly.
Smokers.
Individuals who have undergone gastric or distal ileum resection.
Furthermore, pregnant women must seek appropriate supplements, as well as those who follow a vegan or vegetarian diet.

Vitamin B12 deficiency: the causes
The absorption of vitamin B12 occurs in the intestine, but only after binding with the intrinsic factor produced in the stomach: this vitamin-factor union allows the internalization of the vitamin, which alone could not pass the intestinal barrier.
For this reason, B12 deficiencies are not always primary, i.e., due to its low intake, but can also depend on secondary factors, such as genetic alterations that can lead to intrinsic factor deficiency or intestinal diseases such as Crohn's disease, celiac disease or possible intestinal resections that lead to inevitable malabsorption.
Its deficiencies are very often associated with concomitant folate deficiencies, because they are two vitamins that are intimately linked at the biochemical level. A high folic acid intake very often tends to mask cobalamin deficiency.

Vitamin B12 deficiency: symptoms
Important symptoms of deficiency are "megaloblastic" anemia, with the formation of unripe red blood cells, and neuropathy.
While in milder cases it may cause:
Apathy
Confusion or mood changes such as irritability or chronic depression.

Vitamin B12: how to integrate it in a vegetarian or vegan diet
If you follow a vegan diet it is impossible to avoid vitamin B12 deficiencies, because this vitamin is only present in foods of animal origin. The algae are of little help to meet the daily requirement. The vitamin B12 contained in 'spirulina algae' is present only in trace amounts and little bioavailable.
In supplements, this vitamin must be in the active form, which the body is able to transform more easily and therefore to absorb optimally.
In addition to the intake of supplements, vegans and vegetarians should consider the consumption of vegetable drinks fortified in B12, such as coconut, almond, rice, oat milk.

Vitamin B12: factors that can hinder absorption
It is important to pay attention to some compounds that can decrease the bioavailability of B12, such as alcohol or vitamin C which reduces its content in food.
Also, some drugs can reduce the absorption of vitamin B12.
These include those that act in the stomach such as proton pump inhibitors and antacids.
In fact, by decreasing gastric acidity they create an imbalance on the pH of the stomach that does not allow an optimal link between B12 and intrinsic factor. Instead, binding is necessary for B12 to be absorbed by the intestine.

Vitamin B12 against pernicious anemia
Vitamin B12 is used as a treatment in those rare cases of pernicious anemia, a form of anemia caused by a deficiency in the absorption of this vitamin.
Dosages range from 1 to 5 mg / day: the intake, even if in such important concentrations, did not show any cases of toxicity.
Dosages ​​of 1 mg orally are enough to give good results even in older subjects. In fact, such high values ​​determine an important absorption of the vitamin regardless of the presence of the intrinsic factor.
Furthermore, since B12 is water-soluble, the risk of therapeutic overdose is easily avoided. Should it occur, the vitamin would be readily excreted in the urine.
The therapy must be done under strict medical supervision. It is based on the chronic oral or sublingual intake of the vitamin until blood values ​​are restored, including MCV (mean corpuscular volume of erythrocytes).

Vitamin B12 in the kitchen
Vitamin B12 is a heat-resistant vitamin: this means that cooking does not reduce its bioavailability. However, it is particularly sensitive to ascorbic acid (vitamin C), so it would be good to avoid seasoning foods rich in B12 with lemon or other citrus fruits.
To have important cobalamin inputs, it would be better to favor meat or fish based main courses. Compared to first courses based on cereals; as they are richer.
Concerning meats, the entrails (especially the liver) are particularly rich in it, especially those of ox or sheep.
As for fish, we find large quantities of it in seafood (oysters, mussels), precisely because they are heavily populated by microorganisms producing this vitamin, but be careful not to ruin everything with lemon!
The fermentation process of many vegetables increases the B12 content in food.

In conclusion, you can get Vitamin B-12 easily from animal sources.