B12 Shots at Home: How, Where & How Often to Inject Yourself AZ IV Medics Vitamin B12 (cobalamin) and folate (vitamin B9) are vitamins that serve important functions in the human body. Folate is needed for development and growth of cells (including red blood cells) and synthesis Vitamin B12 is an essential nutrient that plays a key role in energy production, neurological function, and the formation of healthy red blood cells. When levels are optimal, it can support improved How Quickly Do Vitamin B12 Injections Work? Prime Aesthetics