NAD+

NAD+ is a coenzyme present in every living cell, central to the redox reactions that generate cellular energy and required as a substrate by sirtuins and PARP enzymes that regulate gene expression and DNA repair.

Studies measuring NAD+ across age groups have found substantially lower levels in older adults compared to younger ones, a decline linked to reduced sirtuin activity and slower DNA repair in aging models.

This has made NAD+ metabolism a central focus of research into cellular aging, mitochondrial function, and genomic stability.