What is vitamin B12? Vitamin B12 is a family of compounds that contain the mineral cobalt. Vitamin B12 is unique in that when it enters the stomach, it requires stomach acid for digestion. The free B12 binds with a substance in the saliva in the mouth and later with intrinsic factor produced in the stomach. The resulting complex then travels to the last part of the small intestine for absorption. About 50% of this vitamin is absorbed in this manner; when there is any failure in this system, only about 1- 2% is absorbed.
A vitamin B12 can be quite serious if neglected. About 95% of all deficiency cases in healthy people are due from inadequate absorption, rather than from an inadequate intake especially in older people. When we age, our stomachs sometime lose the ability to make intrinsic factor needed for absorption,
The most important function of B12 is in folate metabolism. B12 helps to convert folate to active forms needed for DNA synthesis. Another function is maintaining the myelin sheaths that insulate neurons from each other. Deficiencies can show patchy destruction of these myelin sheaths, which can eventually cause paralysis and sometimes death. This commonly occurs in what is called pernicious anemia (pernicious means “leading to death”). Symptoms (see article) usually develop about 3 years from the onset of the disease and by then, destruction of the nerves can be irreversible. Pernicious anemia starts after middle age and can affect up to 10-20% of older adults.
Infants breast-fed by vegan or vegetarian mothers are at risk for B12 deficiency and long-term nervous system problems such as diminished brain growth, degeneration of the spinal cord and poor intellectual development. Vegetarian diets supply little vitamin 12 unless they include vitamin B12- enriched food or supplements.
For more information on vitamin B12,