Introduction
The term vitamin B12 includes a group of associated materials acknowledged as cobalamins. It’s the largest of all the B complex vitamins and usually has a relative molecular mass of above one thousand. It has a corrin ring made up of four pyrroles with cobalt at the center of the ring. (Nexo, 461-475)
It is believed that animal foods are the only source of vitamin B12 and are mainly attached to foods synthesized by bacteria. Plants do not have the enzymes necessary for vitamin B12 synthesis. In living things cells, there are two vitamin B12 reliant enzymes and they consist of methionine synthase which makes use of the substantial form of vitamin B12 carrying the methyl group attached to the cobalt and the other enzyme is methymalonyl coenzyme mutase which makes use of the element form of the vitamin that is transportation a 5’-adeoxyadenosyl moiety attached to the cobalt. (Krautler, 315-339)
Sources of vitamin B12
The main sources of vitamin B12 are foods of animal origin since microorganisms such as algae and bacteria contain enzymes necessary for Vitamin B12 synthesis. These microorganisms also grow in the intestine as a result of the fermentation of food in the stomach which favors their growth. Mammalian products such as eggs, cheese, butter, milk, and meat are essential providers of vitamin B12 (Finke, 300).
Absorption
Vitamin B12 is bound to proteins in foods and can only be released by the action of a high concentration of hydrochloric acid. This process results in the free form of vitamin B12 which is immediately bound to the glycoprotein namely the R-binders and intrinsic factors both of which help in the absorption of vitamin B12.R-binders prevent the destruction of the vitamins by the acid while intrinsic factors enable the active absorption of the vitamin. The pancreatic proteases digest the R-binders in the duodenum releasing the vitamins which are bound quickly by the intrinsic factors which proceed to the small intestine, where they are absorbed by specific ileal receptors by a process called phagocytosis. (Trugo & Sardinha, 22-33)
Deficiency symptoms
Vitamin B12 is mainly found in animal products hence those stringent vegetarians are at high risk of vitamin B12 deficiency. The signs and symptoms of vitamin B12 deficiency include weakness, loss of appetite, depression, poor memory, tingling in the hands and feet, and poor memory. Lack of vitamin B12 results in pernicious anemia. (Scott & Weir, 63-72)
Assessment of vitamin B12
The elevation of plasma homocysteine and plasma MMA are the best indicators of vitamin B12 deficiency, and high MMA in the body is always associated with low vitamin B12 in the body.MMA alone can not however be used as the only indicator for vitamin B12 deficiency since renal insufficiency can also result in elevated MMA in the blood. Therefore low serum levels of vitamin B12 should be the indicator of vitamin B12 deficiency and could e confirmed by high MMA in the blood. (Markle, 247-356)
Conclusion
Vitamin B12 is therefore necessary for proper body functioning. Its deficiency results in anemia and neurological impairments such as memory loss.
References
Finke, R.G (1998). Vitamin B12 and B12-Proteins, New York, NY, John Wiley.
Krautler, B (1999). Chemistry and Biochemistry of B12, New York, NY, John Wiley.
Markle, H. V (1996).Cobalamin, Critical Reviews in Clinical Laboratory Sciences, Vol. 33, No. 4, pp. 247-356
Nexo, E (1998). Vitamin B12 and B12-Proteins, John Wiley, New York, NY.
Scott, J. M & Weir, D. G (1994). Folate/Vitamin B12 Interrelationships. Essays in Biochemistry, Vol. 28, pp.63-72
Trugo, N. M., Cobalamin, S. F & Cobalamin (1994). Binding Capacity in Human Milk. Nutrition Research, Vol. 14, pp. 22-33.