What is Vitamin B12?

In a nutshell

In a nutshell

  • Vitamin B12 deficiency can cause damage to the brain. This B vitamin is necessary for the proper functioning of the entire nervous system.
  • B12 is required to produce healthy red blood cells and prevent anemia.
  • B12 is only found in animal sources of the diet. B12 deficiency may occur in those who do not eat meat and fish products.
Essential for:




Brain health

Brain health

nervous system

Nervous system


Mood control

Key sources:

Lamb liver


Beef liver


Turkey heart







mackerel, herring, sardines

Mackerel, herring, sardines





Vitamin B12

Vitamin B12, also known as cobalamin, is a nutrient that is necessary for the proper functioning of many of the body's systems. Although B12 is water-soluble like others in the B complex vitamins, this nutrient is stored in the liver in large enough amounts to protect the body from a deficiency for a while. The most common form used in supplements is called cyanocobalamin.

Benefits of the vitamin B12

Like other B vitamins, B12 is necessary for the metabolism of food into energy. This nutrient is also needed in the synthesis of both DNA and RNA for all cells of the body. It is essential for healthy red blood cells, helping to prevent a type of anemia called megaloblastic anemia, which results in extra-large red blood cells that are not mature and reduce the amount of oxygen in the blood that is carried to cells. This B vitamin is also necessary for the proper functioning of the entire nervous system, including the brain, nerves, and neurotransmitters, especially those that control mood.

Vitamin B12 deficiency

Because this specific vitamin is only found in animal sources of the diet, the B12 deficiency may occur in those who do not eat meat products or enough fortified grain products. A deficiency in this nutrient may also occur in those who do not produce enough acid in the stomach and those who do not create a specific protein, called intrinsic factor, in the stomach. Stomach acid is needed to separate the B12 from the protein in food, while the intrinsic factor is required for the vitamin to be absorbed by the body in the large intestine. Those with some gastrointestinal issues, HIV, eating disorders, vegans, vegetarians, and the elderly may be at risk of deficiency. Symptoms may include:
• Sore tongue;
• Loss of appetite;
• Fatigue;
• Depression;
• Psychosis,
• Memory disorders;
• Megaloblastic anemia;
• Nerve and brain damage;
• Neural tube defects.

Vitamin B12 side effects

This nutrient has not been associated with any harmful symptoms, even when administered in more significant than typical doses. Although there is minimal potential for overdose, certain medications may react with B12, resulting in malabsorption of this nutrient and possible deficiency.

Daily Recommended Intake

Only animal food sources and fortified products contain Vitamin B12. The highest levels of B12 can be obtained through eating mollusks, fish, organ meats, beef, pork, dairy products, eggs. Because of the potential for malabsorption from food sources, adults over 50 years of age are recommended to get a large portion of their B12 requirements from supplements or fortified foods.
The recommended daily allowance for this vitamin is as follows:
• 0 - 6 months: 0.4 µg;
• 6 - 12 months: 0.5 µg;
• 1 - 3 years: 0.9 µg;
• 4 - 8 years: 1.2 µg;
• 9 - 13 years: 1.8 µg;
• 14 - adults: 2.4 µg;
• Pregnant  women should take 2.6 µg while nursing women should take 2.8 µg each day.

Sources of vitamin B12

The following foods have high amounts of vitamin B12:
Clam, mixed species (cooked- moist heat) (100g)- 98.9 µg;
Lamb liver (fried) (100g)- 85.7 µg;
Beef liver (fried) (100g)- 83.1 µg;
Veal kidneys (cooked)(100g)- 36.9 µg;
Octopus (cooked- moist heat)- 36 µg;
Pacific oyster (cooked- moist heat) 28.8 µg;
Turkey heart (cooked) (100g)- 28.2µg;
Mussel (cooked- moist heat)- 24 µg;
Black and red caviar (100g)- 20 µg;
Atlantic mackerel, herring (cooked- dry heat) (100g)- 19 µg;
Pork liver (braised)(100g)- 18.7 µg;
Red salmon (smoked) (100g) -18.1 µg;
Chicken liver (cooked) (100g) -16.6 µg.

Other important sources of Vitamin B12:
• Dairy products;
• Eggs.

"Cobalamin" comes from the element cobalt

This nutrient was discovered through scientific research regarding pernicious anemia. Scientists that included George Whipple in 1920, George Richards Minot and William Murphy in 1926, and Edwin Cohn in 1928 all contributed to the discovery of this B vitamin. However, this nutrient was isolated by chemists Mary Shaw Shorb, Karl A. Folkers, and Alexander R. Todd only in 1948. The name cobalamin comes from the element cobalt being present in the compound.