Methylcobalamin is the neurological active form of vitamin B12. The liver does not convert cyanocobalamin, the commonly available form of vitamin B12, into adequate amounts of methylcobalamin, which the body uses to treat or correct neurological defects. Animal studies have shown that high doses of methylcobalamin are effective in neuron regeneration and that there is no known toxicity at these doses. Research shows that this active form of B12 has the unique ability to provoke the regeneration of nerves without adverse side effects. This is because B12 facilitates methylation, the process that creates and maintains nerves and brain chemicals. Research shows that a lack of methylcobalamin causes degeneration of the brain and spinal cord—a condition known as subacute combined degeneration. In this disease, nerves lose their insulation and begin to deteriorate. This process, known as demyelination, occurs in other neurological diseases such as multiple sclerosis and chronic inflammatory demyelinating polyneuropathy.
http://www.ncbi.nlm.nih.gov/pubmed/20045411
