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Vitamin B12 - Food Sources and Deficiency Symptoms of Vitamin B12
Vitamin B12 is a member of the vitamin B complex. It contains cobalt, and so is also known as cobalamin. It is exclusively synthesised by bacteria and is found primarily in meat, eggs and dairy products. Many vegan foods are supplemented with B12.
Vitamin B12 is necessary for the synthesis of red blood cells, the maintenance of the nervous system, and growth and development in children. Deficiency can cause anaemia. Vitamin B12 neuropathy, involving the degeneration of nerve fibres and irreversible neurological damage, can also occur.
Sources of Vitamin B12:
The main sources of vitamin B12 are as:-
- Vitamin B12 is naturally found in foods including meat, eggs, and milk products. Fortified breakfast cereals are a particularly valuable source of vitamin B 12 for vegetarians and vegans.
- It may be found lacking in those practicing vegan diets who do not use multivitamin supplements or eat B12 fortified foods, such as fortified cereals, fortified soy -based products.
- Interestingly, certain insects such as termites have been found to contain B 12.
- Cyanocobalamin is also found in many energy drinks.
Functions of Vitamin B12:
- Methylcobalamin is required for the function of the folate-dependent enzyme , methionine synthase. This enzyme is required for the synthesis of the amino acid , methionine , from homocysteine . Methionine is required for the synthesis of S-adenosylmethionine, a methyl group donor used in many biological methylation reactions, including the methylation of a number of sites within DNA and RNA.
- Vitamin B12 is required by the enzyme that catalyzes the conversion of L-methylmalonyl-CoA to succinyl-CoA. This biochemical reaction plays an important role in the production of energy from fats and proteins.
- Vitamin B12 is needed for cell division and blood formation. Neither plants nor animals make vitamin B12. Bacteria are responsible for producing vitamin B12.
Deficiency of Vitamin B12:
- The deficiency of vitamin B12, is due to inadequate absorption. The cause may be lack of intrinsic factor, a protein produced in the stomach. Vitamin B12 is readily absorbed in the last part of the small intestine i.e. ileum, which leads to the large intestine.
- If a woman has a folate deficiency prior to pregnancy, it will be intensified during gestation and may lead to premature birth and neural tube birth defects, such as spina bifida, in the child.
- Older people may have a vitamin B 12 deficiency because stomach acidity is low, reducing the body's ability to remove vitamin B 12 from the protein in meat. Abnormal growth of bacteria in the small intestine may reduce the absorption of vitamin B 12.
- A deficiency in either B12 or folate can lead to macrocytic anemia, a condition characterized by the production of fewer, but larger red blood cells and a decreased ability to carry oxygen.
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