Yes, NAD+ is a coenzyme. NAD+ is the abbreviation for Nicotinamide Adenine Dinucleotide. It is an essential coenzyme involved in several metabolic processes in the body including cellular energy and mitochondrial health. NAD+ plays a pivotal role in two general sets of reactions in the human body. It facilitates metabolism by synthesizing energy from nutrients. It also works as a helper molecule, binding other enzymes to cause reaction on a molecular level. The body has a limited supply of NAD+. The amount of NAD+ in the body declines with age.