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Shedding Light on the Risks
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Shedding Light on the Risks
& Benefits of Medications Can NAD+ Boosters Keep You Young?
These trendy supplements show promise in treating some ailments, but there’s little evidence for claims that they can ward off aging, or otherwise enhance wellness, in healthy people
August 3, 2026
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As managing partner of a boutique medical spa in King of Prussia, Pennsylvania, Cory Gallagher prides himself on anticipating trends in beauty and wellness. Under his direction, the shop was among the first in the country to offer such state-of-the-art therapies as laser facials and GLP-1 weight-loss drugs. Yet Gallagher also has a skeptical streak. “I’ve gotten so frustrated watching my industry chase hype without stopping to ask whether something actually works,” he says. “You hear a lot of, ‘Well, it probably won’t hurt.’ But that approach burns consumer trust each time the latest and greatest treatment fizzles out.”
In the early 2020s, Gallagher noticed a growing buzz about one cutting-edge nostrum: NAD+ boosters. These dietary supplements, administered orally or intravenously, are touted by marketers and influencers as a “fountain of youth” that can “stop aging in its tracks.” (Google those phrases with “NAD,” and you’ll get dozens of hits.) Their celebrity endorsers include Joe Rogan, Gwyneth Paltrow, Jennifer Aniston, Kendall Jenner, and Hailey Bieber. The latter pair underwent a NAD+ IV drip together on The Kardashians. “I’m going to NAD for the rest of my life and I’m never going to age,” Bieber declared.
On podcasts and social media, biohackers credit NAD+ boosters with enhancing their energy, strength, and mental clarity, even firming their skin and thickening their hair. They often cite scientific studies to back their claims. Spurred by such testimonials, the global market for NAD+ products has surpassed $1.5 billion. The pills, capsules, and beverages are widely available at drugstores and online. Pricey IV infusions and injections, once offered only by specialized clinics, can now be scored at some mainstream med spas as well.
Still, Gallagher wanted to dive deeper into the data before deciding whether to provide NAD+ treatments to his customers. “I’m a research nerd,” he explains. In 2024, he decided to conduct his own study — a systematic review, which attempts to collect and analyze all existing evidence that addresses a specific question.
Aided by independent medical researcher Owoturo Oluwaseun Emmanuel, Gallagher began combing through biomedical databases for studies published in English since 2010 that evaluated wellness- and aging-related impacts of NAD+ supplementation. Out of thousands of papers, he and Emmanuel found 80 animal studies and 33 human trials that focused on relevant areas, including cardiovascular and metabolic function, body composition, physical performance, fatigue, sleep, and skin quality.
Then Gallagher set about analyzing the studies’ findings. “If the research showed NAD boosters worked, we would probably offer them,” he says. “If it didn’t, we wouldn’t.” To edify others, he aimed to publish his results in a peer-reviewed journal.
Like many supplement sleuths, however, he soon learned a perplexing lesson: “Working” can be a matter of interpretation.
Understanding the NAD+ Basics
To navigate the hype around NAD+ boosters, you need to know a bit about the substance they’re meant to boost. Nicotinamide adenine dinucleotide (called NAD+ in its oxidized form) is a coenzyme — a molecule that helps enzymes catalyze chemical reactions. Found in every living cell, it’s crucial to energy production by the tiny powerhouses known as mitochondria. It also plays key roles in cellular and tissue repair.
NAD+ is constantly consumed and recreated as organisms go about their lives. Our bodies synthesize the compound in three main ways: by using vitamin B3 from food as the starting point; by putting the amino acid tryptophan through a series of biochemical transformations; or by recycling nicotinamide, a type of B3 left behind when NAD+ is used by cells.
The idea that elevating NAD+ could ward off aging emerged in the early 2000s, after biologists at the Massachusetts Institute of Technology discovered that the lifespan of yeast could be extended by increasing production of enzymes called sirtuins — and that sirtuin activity depends on NAD+ levels. Other researchers found that NAD+ in human tissues declines with age and in the presence of various metabolic and neurodegenerative diseases. Based on these observations, some hypothesized that replenishing the stuff might protect us from the ravages of time itself.
“It’s a beautiful theory,” says Christopher Martens, Ph.D., director of the University of Delaware’s Center for Cognitive Aging Research. “But it may have overshadowed the science a bit.”
One challenge to supplementing NAD+ is that the molecule is too big and unstable to enter cells intact; if you swallow it, your digestive juices break it down into precursor molecules, which must then be absorbed and reassembled. A more efficient approach is to take a NAD+ precursor — specifically, some form of vitamin B3 — that cells can absorb directly. That raises another challenge: The varieties of B3 found in old-school supplements, niacin and nicotinamide, can cause side effects ranging from headaches to liver damage at high doses.
In 2004, biochemist Charles Brenner, Ph.D., and his then-postdoc Pawel Bieganowski, Ph.D., discovered that animals can create NAD+ from another form of the vitamin, nicotinamide riboside (NR). Brenner and colleagues later showed that NR, like NAD+ itself, can extend lifespan in yeast. Meanwhile, a team led by Shin-Ichiro Imai, M.D., Ph.D., revealed that yet another B3 variant involved in NAD+ synthesis, nicotinamide mononucleide (NMN), was key to regulating sirtuin activity in mammalian cells. These findings offered the hope that NR and NMN could be used to boost NAD+— and perhaps longevity — in people.
By 2015, two pioneers of sirtuin research, Leonard Guarente, Ph.D., and David Sinclair, Ph.D., had formed rival companies to develop supplements and medications based largely on NAD+ precursors. Other entrepreneurs dove in as well. And growing numbers of scientists began investigating the potential therapeutic effects of these previously obscure nutrients.
A decade later, NAD+-boosters have become ubiquitous, but whether they can significantly benefit human health remains unclear. In some areas, there are glimmers of hope. As for turning back our biological clocks, the evidence is far murkier.
The Gaps Between Animal and Human Studies
When scientists first used NR and NMN in animal studies, the results were often thrilling. The supplements succeeded at raising NAD+ levels in recipients’ blood and some body tissues. Researchers reported dramatic improvements in metabolic, mitochondrial, muscular, cardiovascular, and neurological health. Obese mice lost weight. Diabetic mice showed reduced symptoms. Elderly mice grew more active and energetic.
In human trials, both NR and NMN proved more tolerable than niacin or nicotinamide, with fewer side effects and no sign of liver toxicity. However, the therapeutic impacts of NAD+ boosters have tended to be less striking in human subjects — a common phenomenon in clinical research, reflecting differences in physiology, genetics, and other factors between our species and lab-bred rodents.
“We’re not seeing any blockbuster, robust changes in clinical outcomes,” Dr. Martens says. “We’re seeing modest hints of efficacy here and there, but nothing huge.”
He and colleagues published one of the first clinical trials of NR in 2018, testing its effects on cardiovascular function in 60 healthy middle-aged and older adults. Over a six-week period, the supplement slightly improved blood pressure and arterial stiffness in participants whose numbers were above normal, but the changes were not statistically significant. In a 2022 study of older adults with mild cognitive impairments, Dr. Martens’ team found small reductions in blood biomarkers associated with Alzheimer’s disease, but there were no differences in symptoms between participants receiving NR and those on placebo.
By 2023, more than two dozen clinical trials of NAD+ boosters had been conducted, in multiple countries, with mixed — and generally underwhelming — results. In some studies, according to a systematic review published that year, NR or NMN marginally improved insulin sensitivity or blood sugar in people with diabetes; in others, it had no meaningful effect. The same went for measures such as body composition and metabolic function in people with obesity, muscle strength in middle age or older adults, and exercise capacity in healthy young people.
Signs of Promise for Chronic Diseases
Yet there have also been some hopeful signs for these supplements, particularly in treating serious chronic ailments. The most notable example may be a trial of NR, with or without the antioxidant resveratrol, for peripheral artery disease (PAD)—a disorder in which narrowed arteries reduce blood circulation in the legs, often curtailing patients’ mobility and causing severe pain. Other than walking exercise and surgery, few effective treatments are available.
Published in 2024, the study found that after six months, NR markedly improved the distance participants could walk in six minutes — adding 23 feet in those who received treatment, compared to a loss of 35 feet for those on placebo. In participants who took at least 75 percent of the pills, six-minute walking distance improved by 102 feet. (Resveratrol showed no benefit.)
That finding was “really encouraging and exciting,” says the study’s lead author, Northwestern University researcher Mary McDermott, M.D. “This is one of the most promising trials we’ve done.” She’s now conducting a larger, multi-center trial of NR for the disease.
In other early-stage clinical studies, NR has shown promise in reducing symptoms of Parkinson’s disease, slowing progression of amyotrophic lateral sclerosis, and improving coordination in ataxia telangiectasia, a rare neurodegenerative disorder. “What’s emerging from the field,” Dr. Martens suggests, “is that [NAD+ boosters] might be beneficial in certain subgroups of people, particularly those who have diseases or risk factors that would drive an overconsumption of NAD+.”
However, none of this data answers the questions Cory Gallagher set out to investigate: Can NAD+ boosters really forestall some aspects of aging? And if so, do IV drips or injections offer any advantages over oral administration?
The Big Unknowns
Before we examine Gallagher’s findings, some context from Charles Brenner may be helpful. Since discovering NR’s role in NAD+ synthesis, Dr. Brenner has led many groundbreaking studies of the precursor’s biochemical functions and clinical applications. He currently serves as chief scientific advisor to Niagen Bioscience (formerly ChromaDex, to which he sold his own NAD+ booster company in 2017), and as a professor at the University of Helsinki.
With this background, you might expect Dr. Brenner to uphold the Fountain of Youth argument for NAD+ supplements. Instead, he has long argued against it. He rejects the premise that the association between NAD+, sirtuin activity, and lifespan in yeast applies to humans. “NAD boosters are not longevity drugs,” he says. “Neither is anything else on this planet,” he adds, though exercise, vaccinations, and medications can help delay our expiration date. “Humans are endowed with longevity through the interaction of thousands of genes with our environment.”
Dr. Brenner describes NR not as an anti-aging drug, but as “a supplement that can potentially help people age better.” He points to several studies showing that NAD+ precursors can reduce inflammation and oxidative stress, common components in many age-related disorders. He takes a dose daily, in part because he finds it helpful for workout recovery, but also because, “as a person whose technology was developed and commercialized, I feel like it’s a reasonable thing for me to be one of the user base.”
He predicts that NAD+ supplementation will someday become a standard part of the medical armamentarium — much as vitamin B9, or folic acid, is for certain conditions — but he doesn’t pretend to know for sure. “I’m always trying to be the voice of reason in this space,” he says.
Other prominent researchers are equally cautious. “Right now, I don’t think the data are shouting from the rooftops” that most people should be taking NAD+ boosters, says Christopher Martens. One issue is that relatively few clinical trials have been published to date, none of them large enough to be statistically powerful. Another is that some basic facts about NAD+ remain unknown, including how much of it our bodies really need.
Indeed, scientists aren’t yet sure whether reductions in NAD+ accelerate the aging process or merely accompany it. University of Pennsylvania physiologist Joseph Baur, Ph.D., cites a recent study showing that mice retained normal health and muscle function even when their NAD+ levels were reduced by 85 percent, nearly triple the loss with normal aging. “That’s a serious challenge to the idea that NAD levels are dropping in a way that’s doing any damage with age,” says Dr. Baur, whose own mouse research has turned up hints of similar resiliency. “I don’t have a final answer to that.”
Another area of uncertainty around NAD+ boosters: the safety of long-term use. A few animal studies suggest that NR and NMN could potentially fuel the growth of cancer cells or shield them from the effects of chemotherapy. Although niacin and nicotinamide have shown no sign of carcinogenicity over their decades of use (the latter, in fact, is known to protect against some cancers), NR and NMN supplements have a much shorter track record. “It’s important that people recognize that there are theoretical risks that can’t be eliminated,” says Dr. Baur, “and that you’re taking on when you experiment on yourself.”
To IV or Not to IV?
For those who feel drawn to experiment with NAD+ boosters, the marketplace offers a vast cornucopia of products, not all of them created equal. Along with NR and NMN, some contain active ingredients that are less absorbable, like uncut NAD+ or its biochemical twin NADH.
Others rely on newer forms of NR, such as nicotinamide riboside hydrogen malate or tartrate, that — unlike the conventional chloride — scientists have barely begun to investigate. Still others fall back on standard niacin or nicotinamide, whose drawbacks have been discussed above. And because supplements are less strictly regulated in the U.S. than pharmaceuticals, it can be difficult to know if the ingredients on the label match those in the bottle. (Look for brands vetted by a well-established third-party testing organization, such as USP, NSF, or ConsumerLab.)
And then there’s the question of IVs and injectables. Celebrity NAD+ evangelists swear by these methods, which can cost hundreds of dollars per dose. Could they be worth saving up for?
Cory Gallagher made his own decision about NAD+ boosters after spending months plowing through the literature. His systematic review was published in the respected journal Ageing Research Reviews in February 2026 — a rare coup for a non-scientist. The paper stuck mainly to NR and NMN, delivered orally, with a couple of nicotinamide trials included for context. Like previous investigators, he found the collective results to be intriguing but ambiguous. Oral NAD+ boosters “appear generally well-tolerated in the short term, but evidence for clinically meaningful anti-aging or wellness benefits remains heterogenous and inconclusive,” he wrote. Larger, longer-term clinical trials would be necessary to assess the treatments’ therapeutic value.
Gallagher was able to find only a handful of studies of IV or injectable NAD+ boosters. The most recent one, involving 14 participants, found that those who received IV infusions of NR experienced fewer side effects than those who received NAD+ itself, which often triggers intense gastrointestinal symptoms and chest pressure. However, all these investigations had tested only the safety and tolerability of such parenteral treatments (as they’re known) rather than their efficacy. “Evidence supporting parenteral NAD+ delivery for anti-aging/wellness outcomes is currently absent among controlled outcomes trials,” he concluded.
After completing his research and weighing the risks associated with IV supplement delivery — which include infection, vein damage, and allergic reactions — Gallagher chose not to offer NAD+-booster infusions to his med spa’s clients. Someday, if the data warrants, he may change his mind. For now, though, he’s staying off the bandwagon.
“I wish the industry in general wasn’t as quick to rush to the next big thing, and was willing to take a minute,” he says. “I understand the excitement, but not everything new is truly revolutionary.”
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<!-- wp:paragraph --> <p>As managing partner of a boutique medical spa in King of Prussia, Pennsylvania, <a href="https://allureaestheticsllc.com/about/">Cory Gallagher</a> prides himself on anticipating trends in beauty and wellness. Under his direction, the shop was among the first in the country to offer such state-of-the-art therapies as laser facials and GLP-1 weight-loss drugs. Yet Gallagher also has a skeptical streak. “I’ve gotten so frustrated watching my industry chase hype without stopping to ask whether something actually works,” he says. “You hear a lot of, ‘Well, it probably won’t hurt.’ But that approach burns consumer trust each time the latest and greatest treatment fizzles out.”</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>In the early 2020s, Gallagher noticed a growing buzz about one cutting-edge nostrum: NAD+ boosters. These dietary supplements, administered orally or intravenously, are touted by marketers and influencers as a “fountain of youth” that can “stop aging in its tracks.” (Google those phrases with “NAD,” and you’ll get dozens of hits.) Their celebrity endorsers include Joe Rogan, Gwyneth Paltrow, Jennifer Aniston, Kendall Jenner, and Hailey Bieber. The latter pair <a href="https://www.elle.com.au/life/health-wellness/kendall-jenner-hailey-bieber-nad-iv-therapy-27089/">underwent a NAD+ IV drip together on <em>The Kardashians</em></a>. “I’m going to NAD for the rest of my life and I’m never going to age,” Bieber declared.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>On podcasts and social media, biohackers credit NAD+ boosters with enhancing their energy, strength, and mental clarity, even firming their skin and thickening their hair. They often cite scientific studies to back their claims. Spurred by such testimonials, the global market for NAD+ products has <a href="https://www.datainsightsmarket.com/reports/nad-booster-304575">surpassed $1.5 billion</a>. The pills, capsules, and beverages are widely available at drugstores and online. Pricey IV infusions and injections, once offered only by specialized clinics, can now be scored at some mainstream med spas as well.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Still, Gallagher wanted to dive deeper into the data before deciding whether to provide NAD+ treatments to his customers. “I’m a research nerd,” he explains. In 2024, he decided to conduct his own study — a <a href="https://www.cdc.gov/library/research-guides/systematic-reviews.html">systematic review,</a> which attempts to collect and analyze all existing evidence that addresses a specific question.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Aided by independent medical researcher <a href="https://pubmed.ncbi.nlm.nih.gov/?sort=pubdate&term=Emmanuel+OO&cauthor_id=41655607">Owoturo Oluwaseun Emmanuel</a>, Gallagher began combing through biomedical databases for studies published in English since 2010 that evaluated wellness- and aging-related impacts of NAD+ supplementation. Out of thousands of papers, he and Emmanuel found 80 animal studies and 33 human trials that focused on relevant areas, including cardiovascular and metabolic function, body composition, physical performance, fatigue, sleep, and skin quality.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Then Gallagher set about analyzing the studies’ findings. “If the research showed NAD boosters worked, we would probably offer them,” he says. “If it didn’t, we wouldn’t.” To edify others, he aimed to publish his results in a peer-reviewed journal. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Like many supplement sleuths, however, he soon learned a perplexing lesson: “Working” can be a matter of interpretation.</p> <!-- /wp:paragraph --><!-- wp:heading --> <h2 class="wp-block-heading">Understanding the NAD+ Basics</h2> <!-- /wp:heading --><!-- wp:paragraph --> <p>To navigate the hype around NAD+ boosters, you need to know a bit about the substance they’re meant to boost. Nicotinamide adenine dinucleotide (called NAD+ in its oxidized form) is a coenzyme — a molecule that helps enzymes catalyze chemical reactions. Found in every living cell, it’s crucial to energy production by the tiny powerhouses known as mitochondria. It also plays key roles in cellular and tissue repair. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>NAD+ is constantly consumed and recreated as organisms go about their lives. Our bodies synthesize the compound in three main ways: by using vitamin B3 from food as the starting point; by putting the amino acid tryptophan through a series of biochemical transformations; or by recycling nicotinamide, a type of B3 left behind when NAD+ is used by cells. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>The idea that elevating NAD+ could ward off aging emerged in the early 2000s, after biologists at the Massachusetts Institute of Technology discovered that the lifespan of yeast could be extended by increasing production of enzymes called sirtuins — and that sirtuin activity <a href="https://www.nature.com/articles/35001622">depends on NAD+ levels</a>. Other researchers found that NAD+ in human tissues <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0042357">declines with age</a> and in the presence of various <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC6511662/">metabolic</a> and <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC6787556/">neurodegenerative diseases</a>. Based on these observations, some hypothesized that replenishing the stuff might protect us from the ravages of time itself. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>“It’s a beautiful theory,” says <a href="https://www.udel.edu/academics/colleges/chs/departments/kaap/faculty/christopher-martens/">Christopher Martens, Ph.D</a>., director of the University of Delaware’s Center for Cognitive Aging Research. “But it may have overshadowed the science a bit.”</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>One challenge to supplementing NAD+ is that the molecule is too big and unstable to enter cells intact; if you swallow it, your digestive juices break it down into precursor molecules, which must then be absorbed and reassembled. A more efficient approach is to take a NAD+ precursor — specifically, some form of vitamin B3 — that cells can absorb directly. That raises another challenge: The varieties of B3 found in old-school supplements, <a href="https://ods.od.nih.gov/factsheets/Niacin-Consumer/">niacin</a> and <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC7277745/">nicotinamide</a>, can cause side effects ranging from headaches to liver damage at high doses. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>In 2004, biochemist <a href="https://www.helsinki.fi/en/news/rare-disease/introducing-dr-charles-brenner-forever-curious-and-passionate-uncharted-research-questions">Charles Brenner, Ph.D</a>., and his then-postdoc Pawel Bieganowski, Ph.D., discovered that animals can create NAD+ from another form of the vitamin, <a href="https://www.cell.com/fulltext/S0092-8674(04)00416-7">nicotinamide riboside (NR)</a>. Brenner and colleagues later showed that NR, like NAD+ itself, <a href="https://www.cell.com/cell/fulltext/S0092-8674%2807%2900390-X">can extend lifespan in yeast</a>. Meanwhile, a team led by <a href="https://imailab.wustl.edu/dr-imai/">Shin-Ichiro Imai, M.D., Ph.D</a>., revealed that yet another B3 variant involved in NAD+ synthesis, <a href="https://www.sciencedirect.com/science/article/pii/S0021925820693590">nicotinamide mononucleide (NMN)</a>, was key to regulating sirtuin activity in mammalian cells. These findings offered the hope that <a href="https://www.sciencedirect.com/science/article/abs/pii/S1043661810000204?via%3Dihub">NR and NMN could be used to boost NAD+</a>— and perhaps longevity — in people.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>By 2015, two pioneers of sirtuin research, <a href="https://www.elysiumhealth.com/blogs/technical-experts/leonard-guarente-phd?srsltid=AfmBOooBEzu3n3FlWq7KwIfmqPFa1asvDETSRVW38td34f9oCgeDSoGV">Leonard Guarente, Ph.D</a>., and <a href="https://www.nmn.com/news/a-sneak-peek-of-sinclairs-stunning-metrobiotech-lab-and-new-nmn-clincial-trials">David Sinclair, Ph.D</a>., had formed rival companies to develop supplements and medications based largely on NAD+ precursors. Other entrepreneurs dove in as well. And growing numbers of scientists began investigating the potential therapeutic effects of these previously obscure nutrients. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>A decade later, NAD+-boosters have become ubiquitous, but whether they can significantly benefit human health remains unclear. In some areas, there are glimmers of hope. As for turning back our biological clocks, the evidence is far murkier.</p> <!-- /wp:paragraph --><!-- wp:heading --> <h2 class="wp-block-heading">The Gaps Between Animal and Human Studies</h2> <!-- /wp:heading --><!-- wp:paragraph --> <p>When scientists first used NR and NMN in animal studies, <a href="https://www.cell.com/cell-metabolism/fulltext/S1550-4131(16)30495-8?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1550413116304958%3Fshowall%3Dtrue">the results were often thrilling</a>. The supplements succeeded at raising NAD+ levels in recipients’ blood and some body tissues. Researchers reported dramatic improvements in metabolic, mitochondrial, muscular, cardiovascular, and neurological health. <a href="https://pubmed.ncbi.nlm.nih.gov/35643283/">Obese mice lost weight</a>. <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC4882590/">Diabetic mice showed reduced symptoms</a>. <a href="https://www.science.org/doi/10.1126/science.aaf2693">Elderly mice grew more active and energetic</a>. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>In human trials, both <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC7352172/">NR</a> and <a href="https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.868640/full">NMN</a> proved more tolerable than niacin or nicotinamide, with fewer side effects and no sign of liver toxicity. However, the therapeutic impacts of NAD+ boosters have tended to be less striking in human subjects — a common phenomenon in clinical research, reflecting differences in physiology, genetics, and other factors between our species and lab-bred rodents. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>“We’re not seeing any blockbuster, robust changes in clinical outcomes,” Dr. Martens says. “We’re seeing modest hints of efficacy here and there, but nothing huge.”</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>He and colleagues published one of the first clinical trials of NR in 2018, testing its effects on <a href="https://www.nature.com/articles/s41467-018-03421-7">cardiovascular function in 60 healthy middle-aged and older adults</a>. Over a six-week period, the supplement slightly improved blood pressure and arterial stiffness in participants whose numbers were above normal, but the changes were not statistically significant. In a 2022 study of <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/acel.13754">older adults with mild cognitive impairments</a>, Dr. Martens’ team found small reductions in blood biomarkers associated with Alzheimer’s disease, but there were no differences in symptoms between participants receiving NR and those on placebo.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>By 2023, more than two dozen clinical trials of NAD+ boosters had been conducted, in multiple countries, with mixed — and generally underwhelming — results. In some studies, <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC10692436/">according to a systematic review published that year</a>, NR or NMN marginally improved insulin sensitivity or blood sugar in people with diabetes; in others, it had no meaningful effect. The same went for measures such as body composition and metabolic function in people with obesity, muscle strength in middle age or older adults, and exercise capacity in healthy young people. </p> <!-- /wp:paragraph --><!-- wp:heading --> <h2 class="wp-block-heading">Signs of Promise for Chronic Diseases</h2> <!-- /wp:heading --><!-- wp:paragraph --> <p>Yet there have also been some hopeful signs for these supplements, particularly in treating serious chronic ailments. <a href="https://www.nature.com/articles/s41467-024-49092-5">The most notable example</a> may be a trial of NR, with or without the antioxidant resveratrol, for peripheral artery disease (PAD)—a disorder in which narrowed arteries reduce blood circulation in the legs, often curtailing patients’ mobility and causing severe pain. Other than walking exercise and surgery, few effective treatments are available.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Published in 2024, the study found that after six months, NR markedly improved the distance participants could walk in six minutes — adding 23 feet in those who received treatment, compared to a <em>loss</em> of 35 feet for those on placebo. In participants who took at least 75 percent of the pills, six-minute walking distance improved by 102 feet. (Resveratrol showed no benefit.) </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>That finding was “really encouraging and exciting,” says the study’s lead author, Northwestern University researcher <a href="https://www.medicine.northwestern.edu/faculty/directory/profile.html?xid=12615">Mary McDermott, M.D</a>. “This is one of the most promising trials we’ve done.” She’s now conducting a larger, multi-center trial of NR for the disease. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>In other early-stage clinical studies, NR has shown promise in reducing symptoms of <a href="https://www.cell.com/cell-metabolism/fulltext/S1550-4131(22)00045-6?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1550413122000456%3Fshowall%3Dtrue">Parkinson’s disease</a>, slowing progression of <a href="https://www.tandfonline.com/doi/full/10.1080/21678421.2018.1536152">amyotrophic lateral sclerosis</a>, and improving coordination in <a href="https://movementdisorders.onlinelibrary.wiley.com/doi/10.1002/mds.28788">ataxia telangiectasia</a>, a rare neurodegenerative disorder. “What’s emerging from the field,” Dr. Martens suggests, “is that [NAD+ boosters] might be beneficial in certain subgroups of people, particularly those who have diseases or risk factors that would drive an overconsumption of NAD+.” </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>However, none of this data answers the questions Cory Gallagher set out to investigate: Can NAD+ boosters really forestall some aspects of aging? And if so, do IV drips or injections offer any advantages over oral administration? </p> <!-- /wp:paragraph --><!-- wp:heading --> <h2 class="wp-block-heading">The Big Unknowns</h2> <!-- /wp:heading --><!-- wp:paragraph --> <p>Before we examine Gallagher's findings, some context from Charles Brenner may be helpful. Since discovering NR’s role in NAD+ synthesis, Dr. Brenner has led <a href="https://scholar.google.com/scholar?hl=en&as_sdt=0%2C33&q=%22charles+brenner%22+%22nicotinamide+riboside%22&btnG=">many groundbreaking studies</a> of the precursor’s biochemical functions and clinical applications. He currently serves as chief scientific advisor to <a href="https://www.niagenbioscience.com/">Niagen Bioscience</a> (formerly ChromaDex, to which he sold his own NAD+ booster company in 2017), and as a professor at the University of Helsinki.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>With this background, you might expect Dr. Brenner to uphold the Fountain of Youth argument for NAD+ supplements. Instead, he <a href="https://nautil.us/the-longevity-skeptic-305806">has long argued against it</a>. He rejects the premise that the association between NAD+, sirtuin activity, and lifespan in yeast applies to humans. “NAD boosters are not longevity drugs,” he says. “Neither is anything else on this planet,” he adds, though exercise, vaccinations, and medications can help delay our expiration date. “Humans are endowed with longevity through the interaction of thousands of genes with our environment.”</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Dr. Brenner describes NR not as an anti-aging drug, but as “a supplement that can potentially help people age <em>better.</em>” He points to several studies showing that NAD+ precursors can reduce <a href="https://journals.physiology.org/doi/full/10.1152/ajpendo.00242.2023">inflammation and oxidative stress</a>, common components in <a href="https://www.nature.com/articles/s41392-023-01502-8">many age-related disorders</a>. He takes a dose daily, in part because he finds it helpful for workout recovery, but also because, “as a person whose technology was developed and commercialized, I feel like it’s a reasonable thing for me to be one of the user base.”</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>He predicts that NAD+ supplementation will someday become a standard part of the medical armamentarium — much as vitamin B9, or folic acid, is for certain conditions — but he doesn’t pretend to know for sure. “I’m always trying to be the voice of reason in this space,” he says.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Other prominent researchers are equally cautious. “Right now, I don’t think the data are shouting from the rooftops” that most people should be taking NAD+ boosters, says Christopher Martens. One issue is that relatively few clinical trials have been published to date, none of them large enough to be statistically powerful. Another is that some basic facts about NAD+ remain unknown, including how much of it our bodies really need.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Indeed, scientists aren’t yet sure whether reductions in NAD+ accelerate the aging process or merely accompany it. University of Pennsylvania physiologist <a href="https://academyofgeroscience.org/joseph-baur-phd">Joseph Baur, Ph.D</a>., cites a <a href="https://www.cell.com/cell-metabolism/fulltext/S1550-4131(25)00212-8">recent study</a> showing that mice retained normal health and muscle function even when their NAD+ levels were reduced by 85 percent, nearly triple the loss with normal aging. “That’s a serious challenge to the idea that NAD levels are dropping in a way that’s doing any damage with age,” says Dr. Baur, whose own mouse research has turned up hints of similar resiliency. “I don’t have a final answer to that.”</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Another area of uncertainty around NAD+ boosters: the safety of long-term use. A few <a href="https://www.sciencedirect.com/science/article/pii/S0304383526000972#bib35">animal studies</a> suggest that NR and NMN could potentially fuel the growth of cancer cells or shield them from the effects of chemotherapy. Although niacin and nicotinamide have shown no sign of carcinogenicity over their decades of use (<a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC4570055/">the latter, in fact, is known to protect against some cancers</a>), NR and NMN supplements have a much shorter track record. “It’s important that people recognize that there are theoretical risks that can’t be eliminated,” says Dr. Baur, “and that you’re taking on when you experiment on yourself.” </p> <!-- /wp:paragraph --><!-- wp:heading --> <h2 class="wp-block-heading">To IV or Not to IV?</h2> <!-- /wp:heading --><!-- wp:paragraph --> <p>For those who feel drawn to experiment with NAD+ boosters, the marketplace offers a vast cornucopia of products, not all of them created equal. Along with NR and NMN, some contain active ingredients that are<a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC8612620/"> less absorbable</a>, like uncut NAD+ or its biochemical twin NADH. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Others rely on newer forms of NR, <a href="https://pubmed.ncbi.nlm.nih.gov/34066468/">such as nicotinamide riboside hydrogen malate or tartrate</a>, that — unlike the conventional chloride — scientists have barely begun to investigate. Still others fall back on standard niacin or nicotinamide, whose drawbacks have been discussed above. And because supplements are less strictly regulated in the U.S. than pharmaceuticals, it can be difficult to know if the ingredients on the label match those in the bottle. (Look for brands vetted by a well-established third-party testing organization, such as <a href="https://www.usp.org/">USP</a>, <a href="https://www.nsf.org/">NSF</a>, or <a href="https://www.consumerlab.com/">ConsumerLab</a>.)</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>And then there’s the question of IVs and injectables. Celebrity NAD+ evangelists swear by these methods, which can cost hundreds of dollars per dose. Could they be worth saving up for?</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Cory Gallagher made his own decision about NAD+ boosters after spending months plowing through the literature. <a href="https://pubmed.ncbi.nlm.nih.gov/41655607/">His systematic review</a> was published in the respected journal <em>Ageing Research Reviews</em> in February 2026 — a rare coup for a non-scientist. The paper stuck mainly to NR and NMN, delivered orally, with a couple of nicotinamide trials included for context. Like previous investigators, he found the collective results to be intriguing but ambiguous. Oral NAD+ boosters “appear generally well-tolerated in the short term, but evidence for clinically meaningful anti-aging or wellness benefits remains heterogenous and inconclusive,” he wrote. Larger, longer-term clinical trials would be necessary to assess the treatments’ therapeutic value. </p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>Gallagher was able to find only a handful of studies of IV or injectable NAD+ boosters. The <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC12907335/">most recent one</a>, involving 14 participants, found that those who received IV infusions of NR experienced fewer side effects than those who received NAD+ itself, which often triggers intense gastrointestinal symptoms and chest pressure. However, all these investigations had tested only the safety and tolerability of such parenteral treatments (as they’re known) rather than their efficacy. “Evidence supporting parenteral NAD+ delivery for anti-aging/wellness outcomes is currently absent among controlled outcomes trials,” he concluded.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>After completing his research and weighing the risks associated with IV supplement delivery — which include <a href="https://pmc.ncbi.nlm.nih.gov/articles/PMC12182718/">infection, vein damage, and allergic reactions</a> — Gallagher chose not to offer NAD+-booster infusions to his med spa’s clients. Someday, if the data warrants, he may change his mind. For now, though, he’s staying off the bandwagon.</p> <!-- /wp:paragraph --><!-- wp:paragraph --> <p>“I wish the industry in general wasn’t as quick to rush to the next big thing, and was willing to take a minute,” he says. “I understand the excitement, but not everything new is truly revolutionary.”</p> <!-- /wp:paragraph -->