All the cells in your body use NAD and therefore require NMN, its precursor, to function properly. NAD helps cells regulate a number of essential functions that help keep your cells running smoothly, including: •energy metabolism •DNA repair •gene expression •cellular stress responses It’s essential that your cells have plenty of NMN to produce enough NAD to support these functions. Your NMN levels naturally decline over time, and, as a result, your levels of NAD decline, too. This may contribute to some of the health effects you might experience during aging. For example, research has shown that people with different age-related conditions, including diabetes and liver diseases, may have lower levels of NMN and NAD. Test-tube and animal studies also suggest that NMN may play a role in other aspects of aging, including heart and brain health