Used in various biochemical processes, particularly in enzymatic reactions that involve the transfer of methyl groups and the rearrangement of carbon-carbon bonds. It plays a crucial role in the metabolism of amino acids and fatty acids, aiding in the synthesis of DNA and red blood cells. Additionally, it is essential for the proper functioning of the nervous system and is often utilized in medical treatments for conditions like pernicious anemia and certain neurological disorders. Its application extends to research laboratories where it is used to study enzyme mechanisms and metabolic pathways.