Vitamin B12 - Cyanocobalamin - Stimulates Growth of Red Blood Cells

In 1948 two independent groups of workers led by E. L. Smith in Great Britain and L. F. Parker in USA isolated vitamin B12 from the liver. Hodgkin, the 1964 Nobel Prize winner for chemistry, and her co-workers delineated the structural formula of vitamin B12. They concluded that this vitamin was produced only by fungi and bacteria. Human intestinal bacteria also produced appreciable quantities of it. It was effective in a type of anaemia called pernicious anaemia, in as small a quantity as one-millionth part of a gram. Its deficiency in the body occurred usually due to malabsorption from the intestine rather than from malnutrition.

Vitamin B12 is freely soluble in water. It is resistant to boiling in neutral solutions, but is liable to destruction in the presence of alkalies and acids. Other factors that destroy this vitamin are sunlight, alcohol, oestrogen - the female hormone, and sleeping pills.

Deficiency of vitamin B12 is caused more frequently by problems of absorption than by dietary inadequacy. The presence of a sufficient quantity of gastric juice is essential to facilitate its absorption in the intestine. Calcium and protein-rich food greatly help the absorption of this vitamin from the intestines. The amount of vitamin B12 which is not immediately needed by the body is stored in the liver, which is capable of storing relatively large amounts of this nutrient.

About 30 mcg of vitamin B12 are excreted in the normal urine daily. When injected in a large dose upto 100 mcg, upto 90 per cent of the quantity is excreted. Since the absorption of vitamin B12 does not take place in the colon, much of the unabsorbed vitamin B12 is excreted in the stools. This vitamin is also secreted in breast milk for the use of babies.

Recommended Daily Allowance - Vitamin B12


Men 2 mcg
Women 2 mcg
Children 1 mcg
Infants 0.5 mcg
Lactating Women 2.6 mcg

Vitamin B12 Benefits - Functions in the Body

Like vitamin B6, vitamin B12 is essential for the production and regeneration of red blood cells. It is also needed for the proper functioning of the central nervous system. It improves concentration, memory, and balance, and relieves irritability. Vitamin B12 is necessary for proper utilisation of fats, carbohydrates, and proteins for body building. It promotes growth and increases appetite in children. This vitamin is also involved in many vital metabolic ,and enzymatic processes, including the metabolism of folic acid. If the immune cells made in the bone marrow are to mature into active disease-fighters, a sufficient quantity of vitamin B12 and folic acid are necessary.

Vitamin B12 Rich Food Sources

Vitamin B12 is unique amongst vitamins in that it is mostly found in foods of animal origin. Meat, liver, eggs, shrimps, and dairy products are valuable sources of this vitamin. Vegetarians are therefore advised to increase their intake of milk or take vitamin B12 in a tablet form as a supplement.

Rich Food Sources of Vitamin B12 - values per 100g


Pig's liver
Fatty fish
White fish

Vitamin B12 Deficiency Symptoms

A deficiency of vitamin B12 may cause pernicious (destructive) anaemia. It may lead to a poor appetite and retardation of growth in children, chronic fatigue, a sore mouth, a feeling of numbness or stiffness, loss of mental energy, and difficulty in concentration.

Deficiency of vitamin B12 affects every cell in the body, but is most severely felt in the tissues where the cells normally divide rapidly, as in the blood forming tissues of the bone marrow and in the gastro-intestinal tract. The nervous system is also affected and this may lead to degeneration of nerve fibres in the spinal cord and peripheral nerves.

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