Nicotinamide adenine dinucleotide (NAD+) is one of the most important molecules in the human body. It works as a shuttle, transporting electrons to different cells as both a coenzyme and metabolite as needed. NAD+ has a role in several important biologic and metabolic processes. It works in the mitochondria to help generate new cells, maintain cell functioning, and repair DNA responsible for maintaining a healthy metabolism, in turn slowing down the aging process.