NAD is a coenzyme present in every cell. It drives energy metabolism, DNA repair, and cell signaling. Levels drop with age, which has led to interest in supplementation.
Common supplement forms are NADH (the reduced form) and precursors such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). People take them to help maintain energy, sharpen focus, and promote healthy aging.
Manufacturers often suggest taking NAD supplements on an empty stomach. Some people take them with food to avoid stomach upset. Doses vary widely by form and product.
Long-term safety data is thin. Some people experience mild nausea or headache. Safety during pregnancy and breastfeeding has not been established.