NAD+, short for nicotinamide adenine dinucleotide, is a molecule every cell uses to generate energy and repair DNA. Levels appear to fall with age.
That decline has fueled a booming market for NAD+ boosters sold as pills, injections and IV infusions, priced from about $30 to more than $1,000 per session.
A 113-study systematic review published in Ageing Research Reviews in April 2026 tells a more sober story. Its authors examined 33 human and 80 rodent trials from January 2010 to October 2025.
They concluded that while NAD+ boosting shows real biological activity, clinical effectiveness for anti-aging or wellness outcomes remains inconclusive.
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The gap between mice and people
Most consumer NAD+ products contain precursors, molecules the body converts into NAD+. The two dominant ones are nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). Direct NAD+ pills absorb poorly in the gut, so trials focus on the precursors.
In rodents, boosting NAD+ has produced striking benefits for mitochondrial function, exercise capacity and metabolic health. In people, results have been much smaller and less consistent.
A 2025 review in Nature Metabolism reached the same verdict. Although preclinical work supports the strategy, the authors reported, human clinical trials have shown only limited efficacy.
Dr. Shalender Bhasin of the Boston Pepper Aging Research Center summarized the situation for NPR in May 2026.
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"As a hypothesis, as an idea, it's very attractive. But we are still in the early stages of human studies and the health benefits of augmenting NAD+ are yet to be established in large human studies," Bhasin said.
What the best human trials actually found
The strongest positive signals have come from small, targeted studies. Washington University researchers reported in a 2021 Science paper that ten weeks of NMN increased muscle insulin sensitivity in postmenopausal women with prediabetes.
Other short trials have hinted at modest improvements in fatigue, walking capacity in peripheral artery disease and select markers in Parkinson's patients.
What these trials have not shown is a meaningful reversal of aging biomarkers in large, long-term populations. The April 2026 review described the human data on NR and NMN as heterogeneous and often null across functional and metabolic outcomes.
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It also found no randomized trials at all for the IV NAD+ infusions now marketed at longevity clinics.
Christopher Martens, director of the Delaware Center for Cognitive Aging Research, told NPR the science has been outpaced by the hype. "Initially it was exciting," he said. "I think now the cart may be well ahead of the horse."
What consumers should know now
The precursor supplements themselves appear reasonably safe in the short trials completed so far. IV NAD+ infusions are a different story.
Some studies have reported moderate to severe abdominal cramping, diarrhea, nausea and vomiting during administration, and long-term risks in healthy adults remain unstudied.
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Regulators have taken notice of the market's growth. The U.S. Food and Drug Administration confirmed in September 2025 that NMN can be sold as a dietary supplement, reversing an earlier position.
That decision does not evaluate whether the products work, only whether they can be legally marketed.
For anyone weighing an NAD+ purchase, the honest summary is that the biology is genuinely interesting and the human effects documented so far are modest. The strongest claims made in advertising are not yet backed by large, long-term trials.
Readers with specific health concerns should discuss supplement use with their doctor before starting.
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