Vitamin B12 (Cobalamin)

General Info


Vitamin B12 is first released by digestive enzyme activity, and is then transported to the liver where it is stored. The small amount that is not stored is absorbed within the small intestine.

Dietary Origins

Vitamin B12 is produced within the digestive tract of animals. Making animal protein products a rich source of this nutrient. It does not occur in fruits, vegetables, or grains. Vitamin B12 may also found in beef, cheese, chicken, clams, eggs, milk, and oysters.


Vitamin B12 is the name given to a group of naturally occurring compounds referred to as cobalamins. Cobalamin is the generic name of vitamin B12 because it contains the heavy metal cobalt, which gives this water-soluble vitamin its red color. Vitamin B12 is an essential for growth and plays an important role in the metabolism of cells, especially those found in bone marrow, gastrointestinal tract, and nervous tissue. Because the body doesn’t produce vitamin B12 dietary intake is essential, and animal products are the primary food sources. In the stomach, a mediator called Intrinsic Factor or IF is required to carry vitamin B12 from food into the bloodstream. Without intrinsic factor, only a small percentage of vitamin B12 is absorbed. Once absorbed, relatively large amounts of vitamin B12 can be stored in the liver. Vitamin B12 is required for the normal function of all cells.

Toxicities & Precautions


There are no known toxicities or precautions associated with vitamin B12.

Functions in the Body

Biochemical Pathways

Primarily functions as a methyl donor, and is necessary in the synthesis of DNA and facilitating the conversion of homocysteine to methionine.

Hydrogen Carrier

Behaves as a hydrogen carrier in hydrogen transfer processes.


Involved in various components of protein, fat, and carbohydrate metabolism.

Nervous System

Required for the synthesis the insulation around nerves. Also plays a major role in the functioning of the nervous system.

Red Blood Cells

Vitamin B12 is necessary for the growth of red blood cells.

Symptoms & Causes of Deficiency

Vitamin B12 deficiencies are shown commonly as anemia and neurological changes. Deficiency prevents DNA synthesis, which affects the growth and repair rate of all cells. The symptoms of vitamin B12 deficiency also include: abnormally enlarged red blood cells, confusion and memory loss, depression, dermatitis and skin sensitivity, fatigue, loss of appetite, nausea and vomiting, neuropathy, poor blood clotting and easy bruising, tongue and mouth irregularities. The elderly are at highest risk of a vitamin B12 deficiency. Deficiencies in the elderly may include the following: abnormal gait, confusion, delusions, dementia, dizziness, memory loss, and moodiness. Meatless diets are deficient in vitamin B12. Strict vegetarians should be advised to use a vitamin B12 supplement.