METHYLCOBALAMIN STIMULATES SEROTONIN CREATION & IS THE ONLY FORM OF B-12 THAT ACTS ON THE NERVOUS SYSTEM

Though his presentation register annoys me a bit, this particular one is informative and worth the time to listen to, particularly his emphasis on Methylacobalamin and Adensosylcobalamin.  Here is Dr. Edward Group's presentation.  The reason why Methylcobalamin and  Adensosylcobalamin are so important is because these are the most absorbable forms of B-12.  From Dr. E. Group's presentation:

Methylcobalamin is the only form of B12 that can cross the blood-brain barrier without assistance or conversion. Its methyl group stimulates serotonin creation, a neurotransmitter responsible for mood support. It also works directly on brain cells to protect against damage from excitotoxins. ^[1]  Researchers have found large doses of methylcobalamin may offer therapeutic value for those suffering from ALS and multiple sclerosis. ^[2] [3] This is the only form of B12 that acts on the nervous system.

Adensosylcobalamin

Methylcobalamin