Nicotinamide adenine dinucleotide (NAD+) is a vital coenzyme involved in numerous cellular processes. While preclinical studies suggest a role in healthy ageing, human evidence for NAD+ supplementation is currently limited and insufficient to support widespread use.
NAD+ is a critical coenzyme for cellular energy production and DNA repair. While preclinical research suggests NAD+ precursors could offer anti-ageing benefits, human clinical trials are still in their infancy, showing some metabolic improvements but no definitive evidence for broad health or longevity benefits from supplementation.
Nicotinamide adenine dinucleotide (NAD+) is a ubiquitous coenzyme found in all living cells, playing a fundamental role in metabolism as a key electron carrier in redox reactions and as a substrate for enzymes like sirtuins and PARPs, which are involved in DNA repair and gene expression. Cellular NAD+ levels naturally decline with age in various tissues, a phenomenon hypothesised to contribute to age-related physiological decline (Yoshino et al., Science, 2011).
Supplementation with NAD+ precursors, primarily nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN), has been shown in some human studies to increase NAD+ levels in the blood and certain tissues. For instance, a randomised, placebo-controlled trial by Martens et al. (Nature Communications, 2018) found that 12 weeks of NR supplementation significantly increased NAD+ metabolites in healthy, middle-aged and older adults, and improved some markers of mitochondrial function and inflammation, though without significant clinical outcomes. Another study by Elhassan et al. (Cell Metabolism, 2019) demonstrated that NR supplementation in obese, insulin-resistant men improved insulin sensitivity and reduced liver fat. However, these studies are generally small, short-term, and focused on surrogate markers rather than hard clinical endpoints like disease incidence or lifespan.
While NR administration effectively increases NAD+ metabolites in humans, the clinical significance of these increases, particularly for healthy ageing or disease prevention, remains largely undefined.
— Martens et al., Nature Communications, 2018
Harvard Health publications correctly identify NAD+ as a crucial molecule for cellular energy and repair, acknowledging its decline with age. They often highlight the promising preclinical data from animal models, where NAD+ precursor supplementation has shown benefits in improving metabolic health, muscle function, and even extending lifespan in some species. They also rightly point out that the current human research is preliminary, suggesting potential but cautioning against definitive claims regarding anti-ageing or disease-preventing effects in humans without more robust evidence.
While Harvard Health is generally cautious, some articles might lean into the 'potential' of NAD+ supplements without sufficiently emphasising the significant gap between observed increases in NAD+ metabolites and tangible, clinically meaningful health outcomes in humans. The enthusiasm often generated by animal studies, particularly those showing lifespan extension, can overshadow the fact that these effects rarely translate directly to humans. Furthermore, the optimal dosage, duration, and specific conditions under which NAD+ precursors might be beneficial in humans are still largely unknown, and the effects observed in metabolic disease states may not apply to healthy individuals.
For individuals seeking to optimise their healthspan, relying on NAD+ precursor supplements at this stage is premature. Lifestyle interventions such as regular exercise, a balanced diet, and adequate sleep are well-established methods for supporting cellular health and endogenous NAD+ pathways. While NAD+ precursors are generally considered safe, their long-term efficacy and potential side effects in healthy populations have not been thoroughly investigated. Until more rigorous, large-scale, long-term human trials demonstrate clear clinical benefits, prioritising foundational health behaviours remains the most evidence-based approach.
Vitaei verdict
The anti-ageing and broad health benefits of NAD+ supplementation are currently overstated by the evidence; while promising in preclinical models, human data is limited to surrogate markers and small, short-term studies.