Vitamin B12 (cobalamin)

Vitamin B12

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 actually stored in the liver in large enough amounts to protect the body from a deficiency for a period of time. The most common form used in supplements is called cyanocobalamin.

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 important 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.

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

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 produce a special 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 needed for the vitamin to be absorbed by the body in the large intestine. Those with certain gastrointestinal problems, 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 overdose


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

Daily Recommended Intake and sources of B12


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;
• Women who are pregnant should take 2.6 µg while nursing women should take 2.8 µg each day.

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, that 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.