NAD+

What Is NAD+?

NAD+, short for nicotinamide adenine dinucleotide, is a coenzyme found in every living cell, meaning it helps other enzymes carry out their reactions rather than acting alone. Its central job is participating in redox reactions, the chemical processes cells use to convert nutrients into usable energy, which makes it fundamental to basic cell function.

Beyond energy production, NAD+ also serves as fuel for a separate group of proteins called sirtuins, which are involved in regulating gene expression, DNA repair, and cellular stress responses. Because both of these roles decline in significance as NAD+ levels change, researchers have spent the last two decades studying whether restoring NAD+ levels could support healthier aging.

What NAD+ Is Being Researched For

• Cellular Energy Metabolism

  The foundational role of NAD+ is its participation in redox reactions central to energy production, DNA repair, and chromatin remodeling, functions that touch nearly every aspect of cell biology.^[1]

• Raising NAD+ Levels Through Supplementation

  A major area of research has tested whether precursor compounds, molecules the body can convert into NAD+, actually raise NAD+ levels in humans. A controlled trial found that nicotinamide riboside supplementation was well tolerated and increased NAD+ levels in healthy middle-aged and older adults.^[2]

• Reassessing the Evidence in Human Aging

  More recently, researchers have taken stock of the accumulated human trial data and found a more complicated picture than animal research originally suggested. A 2025 review concluded that evidence for an age-related NAD+ decline in humans has been consistently observed in only a limited number of studies, and that human trials of NAD+ precursors have shown limited efficacy so far.^[3]

How NAD+ Works

• Powering Cellular Energy Production

  Research points to NAD+ acting as an electron carrier in the chemical reactions that convert nutrients into ATP, the molecule cells use as their primary energy currency. Without adequate NAD+, this energy production process becomes less efficient.^[1]

• Fueling Sirtuin Activity

  Research points to NAD+ serving as a required cofactor for sirtuins, a family of proteins involved in regulating gene expression, DNA repair, and how cells respond to stress. Since sirtuins can't function without NAD+, the availability of NAD+ directly affects how active this system can be.^[1]

• A More Complicated Human Picture Than Animal Models Suggested

  Research points to NAD+ decline being well established in animal models, but the human evidence has been harder to pin down. Reviewers have noted that extrapolating from rodent data isn't straightforward, and that more tissue-specific human research is needed to understand where and how much NAD+ actually changes with age.^[3]

Reconstitution and Handling

NAD+ is typically supplied as a lyophilized powder in a sealed vial and reconstituted with bacteriostatic water before use in a research setting. Water should be added slowly rather than injected directly into the powder, and the vial should be swirled, not shaken.

Since the amount of water used affects the concentration of the final solution, researchers often use a dosage calculator to work this out before mixing. Once reconstituted, the solution is kept refrigerated to help preserve its stability.

Key Takeaways

NAD+ sits at the center of two of the cell's most fundamental systems: energy production and sirtuin-dependent stress regulation, which is why its decline has drawn so much research attention. Human clinical trials have confirmed that some precursor compounds do raise NAD+ levels, but a recent, more skeptical review found the case for age-related decline and supplementation benefit in humans is less settled than earlier animal research suggested. This is a genuinely active and evolving area of research rather than a closed question.

Frequently Asked Questions

Sources and Research

1. Covarrubias AJ, Perrone R, Grozio A, Verdin E. NAD+ metabolism and its roles in cellular processes during ageing. Nat Rev Mol Cell Biol. 2021;22(2):119-141.
2. Martens CR, Denman BA, Mazzo MR, et al. Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD+ in healthy middle-aged and older adults. Nat Commun. 2018;9(1):1286.
3. Vinten KT, Trętowicz MM, Coskun E, van Weeghel M, Cantó C, Zapata-Pérez R, Janssens GE, Houtkooper RH. NAD+ precursor supplementation in human ageing: clinical evidence and challenges. Nat Metab. 2025;7(10):1974-1990.