Vitamin B12 Deficiency: What are the consequences?

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Vitamin B12 : An essential part of energy production

The main powerhouses for energy production within  the cell are the mitochondria. Within the mitochondria, fatty acids, sugars and amino acids can be converted to energy in the form of ATP via the glycolysis, Krebbs cycle and the Electron Transport chain. . Whilst is it is generally accepted that the B group vitamins play an essential role in energy production, vitamin B12 has several unique roles to play. Through its interaction with the folate and methylation cycles, methylcobalamin contributes the methyl group that is essential for the production of creatine (2-(Methylguanidino)ethanoic acid). In the muscles creatine and creatine phosphate supply "instant" energy through the conversion of creatine phosphate to ATP.. Carnitine, formed from the break-down of N-methyllysine is essential for transport of free fatty acids into the mitochondria for use in energy production. In the mitochondria, adenosylcobalamin serves as an essential co-factor in the enzyme methylmalonyl-Co mutase, which utilizes odd chain fatty acids and ketones for energy production. A deficiency of adenosylcobalamin can in itself lead to alterations in mitochondrial morphology and function..

Deficiency in adenosylcobalamin leads to the accumulation of methylmalonic acid, which disupts normal glucose and gluatmic acid metabolism in the cell due to its inhibitory activity on the Krebs cycle and by inhibition of ATP synthase. Continued deficiency of adenosylcobalamin, with resultant reduction in energy output can lead to anorexia, lacrimation, alopecia, and eventual emaciation. In addition there is a build up of lesions in the liver and the development of optic neuropathies

Several studies have also shown that mitochondrial function can be affected by the generation of reactive oxygen species (ROS), which can result from decreased levels of glutathione within the cells due to VB12 deficiency and also because vitamin B12 is known to be a scavenger of nitric oxide.

In summary vitamin B12 deficiency has a dramatic effect on energy levels within the cell due to decreased creatine phosphate, reduced fatty acid uptake into the mitochondria, the toxicity of methylmalonic acid and increased levels of ROS>. .

Further Information on the role of vitamin B12 in energy production and mitochondria