NMN supplements boost blood levels but not health – what the research actually shows

Nicotinamide mononucleotide has become wildly popular in wellness circles. Most people call it NMN. Social media influencers tout it as a “fountain of youth.” Wellness websites promise it can “reverse cellular ageing” and “boost energy like never before.”

The marketing enthusiasm has created a booming supplement industry. But leading researchers warn the science has not caught up.

“Industry marketing is five steps ahead of the science and research that still needs to be conducted,” says Dr. Wallace, commenting on the rapid growth of anti-ageing supplements. He notes that “the nutrition community has a history of getting overexcited and letting marketing lead the messaging to consumers before large, long-duration trials confirm the effects.”

What does the actual research show about NMN’s anti-ageing claims?

The most rigorous human study yet

Keisuke Okabe from the University of Toyama led one of the most rigorous studies of NMN in humans. His team monitored 30 healthy adults for 12 weeks. Half took 250 mg of NMN daily, while the other half received placebo tablets—dummy pills with no active ingredients.

The researchers regularly tested participants’ blood, measuring NAD+ (nicotinamide adenine dinucleotide)—a molecule that helps cells produce energy. NAD+ levels naturally decline with age. Supplement companies claim that boosting NAD+ can slow or reverse ageing.

Okabe’s team found that NMN increased NAD+ levels in the blood, but the results were unexpected.

“Clinical metabolic effects were not apparent,” the researchers reported. Clinical metabolic effects refer to actual changes in how the body functions day to day. Despite higher NAD+ levels in blood tests, participants felt no different.

“Evidence of its effect on humans is still scarce,” Okabe and his colleagues concluded.

The gap between blood tests and real benefits

The study identified a significant issue with current NMN research: changes in blood chemistry do not necessarily translate into health benefits.

“This study did not demonstrate the consequences of increased NAD+,” Okabe’s team stated.

This finding challenges a central assumption underlying NMN marketing. Supplement companies claim that raising NAD+ levels automatically provides anti-ageing benefits, but the research shows this connection remains unproven.

L. Yi, who led another major clinical trial, reported similar results. Her multicentre study, which tested a proprietary NMN formulation, examined various doses in healthy middle-aged adults.

“NMN supplementation increases blood NAD concentrations and is safe and well tolerated,” Yi concluded. However, like Okabe’s study, this research focused on blood chemistry rather than actual health outcomes.

Muscle tissue shows no change despite blood results

Okabe’s study revealed another important limitation in current NMN research. The team measured NAD+ only in blood, not in muscle tissue—where anti-ageing effects would theoretically be most relevant.

“Many studies have failed to increase NAD+ levels in the skeletal muscle,” the researchers noted. Skeletal muscle refers to the muscles that move the body and maintain strength with age.

This highlights a significant knowledge gap. Blood tests may show increased NAD+ levels, whilst muscles—the tissues that actually need the molecule for strength and energy—remain unaffected.

Okabe emphasised that “more evidence is necessary to establish the safety and efficacy of NMN. In addition, data on NAD+ metabolism in humans during NMN supplementation are still missing.”

Mouse studies fail to translate to human benefits

Much of the excitement surrounding NMN stems from dramatic results in laboratory animals. Studies show that NMN can extend lifespan in mice and improve various markers of ageing. However, ageing experts urge caution when extrapolating these results to humans.

“We would all love to find the proverbial fountain of youth,” says Hokeness, Ph.D., an expert at Bryant University. “However, it is important to realise that ageing is a complex process that involves cell processes, and it can be impacted by your genes, your lifestyle habits and choices, and things we may not even know about yet.”

Recent research explicitly warns about this challenge of translation. The authors note that “translating these findings to humans requires cautious optimism” because animal models of ageing do not fully replicate human ageing processes.

Emerging safety concerns

New research has revealed potential risks that supplement marketing rarely mentions. Niti Kumari and Brian J. North from Creighton University School of Medicine published troubling findings in 2025.

Their study found that “continuous NMN supplementation in cancer pre-disposition conditions might enhance development and progression of skin cancer” in mice exposed to ultraviolet (UV) light.

This finding adds to broader safety concerns among researchers. Leading experts on NAD+ biology warn that “there might be a risk that boosting NAD+ could drive tumour growth.”

They note that whilst NAD+ promotes DNA repair pathways, “NAD+ depleting drugs are currently under development as cancer chemotherapeutics.” The relationship between NAD+ and cancer appears complex and potentially risky.

Dr. Dinetz, commenting on these concerns, explains that “excess NAD+ that can result from taking NMN may promote tumorigenesis, which is the growth of cancer cells into tumours, given the NAD+’s critical role in promoting cell division.”

Patient reports cannot replace controlled trials

Some physicians report positive effects in patients taking NAD+ supplements. Dr. Dinetz notes, “Clinically, some patients report improved energy, recovery, and cognitive sharpness.” However, these observations differ from controlled clinical trials. Individual reports cannot distinguish between actual supplement effects and placebo responses, where people feel better simply because they expect to. “Animal studies show promising longevity effects, but human trials are still in early stages,” Dr. Dinetz acknowledges.

Researchers demand longer trials before claims

Christopher R. Martens, who studies related NAD+ supplements, emphasises the limitations of current research. His work on nicotinamide riboside—a compound similar to NMN—shows the same pattern of elevated blood levels without clear health benefits.

“More targeted studies (e.g., phase II clinical trials) with fewer outcomes based on two-sided statistical inference, are needed,” Martens explains. Phase II clinical trials are larger, more rigorous studies designed to test whether treatments actually work.

Martens also warns about dosing. “The dose tested in the present study exceeds the label-recommended dose and should be considered investigational until further work can be performed to confirm the safety and efficacy of higher doses.”

Even supplement advocate Katz admits the evidence remains incomplete: “We are still a ways from a complete understanding of all of the situations in which supplementation is clearly warranted, for what specific outcomes, and at what dose.”

Leading experts reject current anti-ageing claims

The gap between marketing hype and scientific reality has led to warnings from leading ageing researchers. S. Jay Olshansky of the University of Illinois at Chicago, Leonard Hayflick, and Thomas T. Perls, along with 51 other ageing researchers, have issued a clear statement.

Their position: “No currently marketed anti-aging products are being marketed with proven scientific efficacy.” They emphasise that “there are currently no scientifically proven antiaging medicines, but that legitimate and important scientific efforts are under way to develop them.”

This reflects the scientific consensus. The science of ageing is advancing rapidly, with legitimate researchers making real progress in understanding how we age. However, consumers should approach current anti-ageing supplement claims with healthy scepticism until larger, longer studies demonstrate their effectiveness.