NAD⁺

Nicotinamide adenine dinucleotide

NAD⁺ (nicotinamide adenine dinucleotide) is a coenzyme present in every living cell — one of the most fundamental molecules in biology. It sits at the centre of how cells turn nutrients into usable energy, and it also serves as a substrate for a family of enzymes involved in DNA repair and gene regulation. Cellular NAD⁺ levels are known to decline with age, which is why the molecule features so prominently in metabolic and longevity research.