Though Vitamin B-12 is generally promoted for its health benefits, each B vitamin has unique functions. Any B vitamin on its own in an isolated form, it is not as effective as when taken in complex form with the other B-vitamins present. B-vitamins are responsible for maintaining the integrity of multiple biochemical reactions throughout the body involved in maintaining proper DNA repair, energy production, focus, memory, immunity, metabolism (including balancing blood sugar, blood pressure, cholesterol) as well as cellular rejuvenation of hair, skin, and nails.