NADH stands for "nicotinamide adenine dinucleotide (NAD) + hydrogen (H)." This chemical occurs naturally in the body and plays a role in the chemical process that generates energy. People use NADH supplements as medicine.NADH is used for improving mental clarity, alertness, concentration, and memory; as well as for treating Alzheimer’s disease. Because of its role in energy production, NADH is also used for improving athletic endurance and treating chronic fatigue syndrome (CFS).