NAD+ plays a key role in cellular function, supporting energy metabolism, DNA repair processes, cellular ageing pathways and normal immune cell activity.

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme found in every cell. It carries electrons through reactions that help convert nutrients into ATP—the usable energy that powers cellular activity. NAD+ also supplies enzymes involved in DNA repair, stress responses and metabolic signaling. Its essential biological role is well established, but the benefits of NAD+-boosting products remain under study.

NAD+ performs two essential functions that support normal cellular activity:

1. 1.Energy metabolism. NAD+ cycles between its oxidized form (NAD+) and reduced form (NADH), carrying electrons through pathways that convert carbohydrates, fats and proteins into ATP.
2. 2.Cellular signaling and repair. Enzymes including sirtuins and PARPs use NAD+ during metabolic regulation, cellular stress responses and DNA repair.

These roles explain why NAD+ is widely studied in metabolism, cellular health and aging biology.

NAD+ levels appear to decline in several tissues with age. Researchers link this change to lower NAD+ production, altered recycling and greater activity from NAD+-consuming enzymes involved in inflammation, stress responses and DNA repair.

This is part of normal aging biology, not a diagnosis. Scientists are studying whether restoring NAD+ can influence human health, but results depend on the compound, dose, population and delivery route.

1. 1.Energy metabolism. NAD+ is essential to pathways that help cells convert nutrients into ATP. Raising an NAD+ biomarker, however, does not guarantee a noticeable energy boost.
2. 2.Healthy-aging research. NAD+ pathways change with age, making them an important research target. Human studies have not established that supplementation slows or reverses aging.
3. 3.Metabolic and cellular function. Early trials of NR and NMN report biomarker changes and some outcome-specific effects, but findings remain mixed.

Human research has focused mainly on NAD+ precursors such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), rather than direct NAD+ nasal sprays or infusions.

Trials show that NR and NMN can raise NAD-related metabolites in blood or cells. Some studies report specific outcomes in defined populations, but results across energy, physical function, metabolism and healthy aging are inconsistent.

A 2026 systematic review concluded that NAD+ augmentation has clear biological activity, while clinical effectiveness for anti-aging and wellness remains inconclusive. Evidence from oral precursors should not automatically be applied to direct NAD+ products or other delivery routes.