Cobalt is a component of vitamin B12. The average body content of cobalt is less than 1 mg and it is stored in the muscles, bone, liver and kidneys. The only known role of cobalt is as part of the vitamin B12 molecule. Many of the functions of vitamin B12 are mediated through the cobalt portion of the molecule. This includes the synthesis of DNA, production of red blood cells, maintenance of nerve function and detoxification of cyanide.


Absorption and metabolism

Cobalt is absorbed as part of the vitamin B12 molecule.



A deficiency of cobalt is equivalent to a deficiency of vitamin B12 with symptoms of pernicious anemia, nerve disorders and abnormalities in cell formation. However, these symptoms cannot be treated with cobalt alone.



Green leafy vegetables, some fish, liver, kidney and milk contain cobalt. Some of the cobalt in meat, fish and dairy products is present as vitamin B12 and some in other forms. In vegetables and cereals, it is present in other forms and is therefore of little use to humans.


Recommended dietary allowances

There is no RDA for cobalt. World Health Organization sources have suggested a minimum daily intake of 1 mcg. Most intakes are higher and vary according to the amount of mineral present in the soil. For example, intake is much higher in the USA than in Japan.


Toxic effects of excess intake

In animals, large intakes of cobalt (4 to 10 mg per kg of body weight) have caused anemia, loss of appetite and low body weight. Other toxic effects are goiter, hypothyroidism, overproduction of red blood cells and heart failure. High dietary protein levels may protect against cobalt toxicity.


Therapeutic uses of supplements

There are no uses for cobalt supplements. Radioactive cobalt-60 is used to treat some cancers.