Vitamin B12 is an essential micronutrient, a basic water-soluble vitamin for the proper functioning of our body as a whole. It helps the correct absorption of proteins and is also involved in the formation of our red blood cells. In addition, its presence in adequate doses affects the good condition of the connections of our central nervous system and the maintenance of brain functions. The different foods, of animal origin, are almost the only source from which to obtain it naturally.

Meats
Meat in general (beef, pork, chicken, lamb) is one of the main sources of vitamin B12 , which is why people who follow a vegetarian or vegan diet, who do not eat this type of food, have to watch periodically check the levels of this vitamin in your body before the possibility of having to supplement your diet with vitamin B12 supplements.
Virtually any meat is capable of providing us with vitamin B12, but the richest in its content is rabbit meat with 10ug (micrograms) per 100 grams, followed by lamb meat with 2.62ug/100 grams and then meat veal , around 1ug/100, and pork with 0.6ug /100 grams. Of course, as stated in the Spanish Food Composition Database (BEDCA), these amounts vary depending on the piece of meat in question, but they undoubtedly point to this food as an undoubted source of this valuable vitamin.
Viscera
If the meat from animals contains a considerable amount of B vitamins and, specifically, B12, the viscera are its best kept ‘treasure', because, for example, 100 grams of cow or beef liver (raw) they provide 81ug and if we talk about chicken liver , with which you can make delicious recipes, its content is the not insignificant amount of 25ug of vitamin B12 per 100 grams.
Mollusks
Some foods that the sea gives us are also an excellent option to provide the body with that essential nutrient that strengthens the immune system, also enjoying the exquisite flavor of seafood.
Bivalves are the most interesting source, since 100 grams of oysters can provide us with up to 16.5 ug, and the same amount of mussels can give us a total of 8 ug of vitamin B12. For their part, raw clams only contain traces of this vitamin, but canned clams are a source to consider as they provide up to 5ug/100g.
Blue Fish
We know the beneficial properties of oily fish, which is especially healthy for our cardiovascular system due to its high content of healthy fatty acids, such as Omega 3 . In addition to taking care of our heart, fish such as salmon, tuna or sardines provide significant amounts of vitamin B12. An excellent slice of grilled salmon of 100 grams will provide your body with 4ug of vitamin and if you like tuna better, you should know that it contains the same amount. For its part, 100 grams of sardines suppose to ingest more than double, that is, about 8.5ug/100 grams.
Here you can learn more about what are the blue fish .
Cephalopods
Continuing with the vitamin intake that we can obtain from foods from the seas and oceans, squid and cuttlefish with 2.5ug of vitamin B12 per 100g of food are the best. The octopus surpasses them, specifically with about 3ug of vitamin B12 per 100g of octopus, but it must be taken into account that during cooking it loses practically all of the vitamin it contains.
Egg
The egg contains in its white and yolk all the essential amino acids that the body needs together with proteins of high biological value, which is why it is considered a superfood by many people. As if all this were not enough, the egg yolk is also rich in vitamin B12, providing 4.7ug per 100 grams.
Dairy products
Although not in large quantities, whole cow's milk also provides vitamin B12, specifically 0.3ug of vitamin B12 per 100g of this food. On the other hand, some of its derivatives, mainly certain types of cheese, are a source to take into account when ingesting this nutrient that we need on a daily basis. At the top of the ranking of the cheeses that contain the most vitamin B12 are two: Emmental cheese with 2.2ug of this vitamin per 100 grams and Parmesan cheese with 1.5ug of this vitamin per 100 grams.
Now that you know the foods with vitamin B12 and the doses that they can provide us, we recommend you read this other article on the Symptoms of a lack of vitamin B12 .