NR vs. NMN: What a New Head-to-Head Independent Study Actually Found Using Tru Niagen

If you've been navigating the world of NAD+ supplements, you've almost certainly run into the NMN vs. NR debate. It's been a fixture of wellness forums, longevity podcasts, and supplement marketing for years—and it has largely played out in the absence of a definitive human study directly comparing the two at the same dose.

That changed in early 2026.

An independent peer-reviewed study published in iScience, a Cell Press journal, directly compared nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) head-to-head in healthy human adults—same participants, same dose, same controlled conditions. The researchers were based at the University of Bergen in Norway and conducted the study entirely independent of any commercial interest.

The results were unambiguous enough that the researchers made a decision mid-study that speaks for itself: they discontinued NMN and ran the remainder of their experiments using NR only.

Here's what the science showed—and what it means for anyone trying to make an informed decision about their NAD+ supplement.

NR vs. NMN: Why a Head-to-Head Study Matters

NR and NMN are both NAD+ precursors—molecules your body can use to produce nicotinamide adenine dinucleotide (NAD+), a coenzyme found in every cell that plays a central role in energy metabolism, DNA repair, and cellular resilience. Both have generated significant scientific interest. Both are sold widely as supplements.

For years, the comparison between the two has relied on separate studies using different doses, different populations, different durations, and different methods. Defenders of NMN pointed to animal studies. Defenders of NR pointed to a larger and longer-established body of human clinical evidence. But no single study had put them side by side in the same human trial—until now.

"People have been asking for head-to-head comparisons of NR and NMN in humans. The data [show] that at 1.2 g/day, NR had 2.3x the blood NAD-boosting activity versus NMN."

— Dr. Charles Brenner, PhD, discoverer of NR as an NAD+ precursor vitamin and Chief Scientific Advisor at Niagen Bioscience, commenting on the Berven et al. study

The Study Design: Why This Trial Is Different

The Bergen study—Berven et al., published in iScience (Cell Press), 2026—was a crossover pharmacokinetic trial in healthy adults. Here's what made the design particularly valuable:

• Same participants: The crossover design meant the same six healthy adults took both NR and NMN, eliminating individual variation as a confounding factor.
• Same dose: Both compounds were administered at 1,200 mg/day (1.2 g/day)—a clinically relevant dose consistent with existing human NR research.
• Controlled washout: Participants took NR for 8 days, followed by a 20-day washout period, then received NMN—or vice versa—followed by another washout. This protocol is standard in pharmacokinetic crossover trials to prevent carry-over effects.
• Independent: The study was conducted with no manufacturer involvement of any kind. Researchers at the University of Bergen purchased Tru Niagen®—containing Niagen® NR (nicotinamide riboside chloride, or NRCl), identified by name in the Berven et al. iScience publication—commercially, off the shelf. The form of NMN used was similarly independently sourced from the brand ProHealth.
• Published in a peer-reviewed Cell Press journal: iScience is a multidisciplinary open-access journal published by Cell Press, the same publisher behind Cell and Cell Metabolism. This is primary literature, not industry white paper.

This level of methodological rigor and independence is what separates this study from much of the NMN promotional material circulating in the supplement space.

The Results: Niagen NR Outperformed NMN by 2.3-Fold

The primary outcome was blood NAD+ elevation—the most direct measure of how effectively a compound increases NAD+ levels in the human body.

Same dose. Same participants.

At 1,200 mg/day, NR increased blood NAD+ by 161% after 8 days of supplementation. NMN, at the same dose in the same participants, increased blood NAD+ by 67%. The researchers calculated this as a 2.3-fold advantage for NR—and noted the advantage was so clear that they chose not to continue using NMN in subsequent phases of their research program.

The NR advantage held up even after accounting for a potential molecular weight advantage for NMN. Because NMN has a higher molecular weight than NR, a given mass of NMN provides fewer molar equivalents of the compound. When the researchers corrected for this—giving NMN a theoretical 15% boost in the calculation—NR still outperformed NMN by a substantial margin.

NR produced a greater NAD increase, only NR was investigated further to reduce participant burden.

— Berven et al., iScience (Cell Press), 2026

The Biology: Why NR Has a Structural Advantage

NMN requires an extra metabolic step

To enter most cells and be used to make NAD+, NMN must first be converted into NR. This conversion step—catalyzed by an enzyme called CD73 on cell surfaces—makes it less efficient. NMN is, in a sense, a precursor to NR, not a direct parallel to it.

NR, by contrast, crosses cell membranes directly via nucleoside transporters. It enters cells as-is and is immediately available to be converted into NAD+. Fewer steps mean less potential for loss along the way.

Not all NMN products contain what they claim

There's a related issue worth noting. Quantitative testing in 2021 has found that the quality of NMN supplements varies widely—and some products marketed as NMN contain little or no NMN at all. This is distinct from the efficacy question, but it compounds the challenge for consumers trying to evaluate NMN as a category.

Niagen NR, by contrast, is manufactured under rigorous quality standards, with every batch tested for potency, purity, and safety. Every lot of Tru Niagen is fully traceable through our certificate of analysis transparency platform.

A Note on the Christen Study and Why Context Matters

Because we're a science-backed company, we want to present all science that's published. In the interest of presenting the full picture, it's worth acknowledging a separate study, published in Nature Metabolism in 2025 by researchers associated with Nestlé Health Science, that compared NR and NMN at 1,000 mg/day over 14 days in a larger cohort (approximately 60 participants).

That study found no statistically significant difference in NAD+ elevation between NR and NMN at that dose.

There are several important methodological distinctions between the two studies:

• Dose: The Christen study used 1,000 mg/day. The Bergen study used 1,200 mg/day. The 20% dose difference may be relevant given that NAD+ response is dose-dependent.
• Fed vs. fasted conditions: The two studies may have differed in dosing protocol (fed vs. fasted), which can meaningfully affect absorption pharmacokinetics for both compounds.
• Study design and population: The Bergen study was a controlled crossover with the same participants receiving both compounds sequentially; the Christen study used a parallel-group design.
  

Scientific disagreement between studies is normal and expected, especially in a relatively young field. The honest interpretation is that the data on NR vs. NMN is not fully settled—and the most statistically rigorous study available thus far is the head-to-head crossover data, at 1,200 mg/day in humans, shows NR with a 2.3-fold advantage after eight days of supplementation. And the researchers purchased Tru Niagen for their study, so Niagen Bioscience and Tru Niagen were not directly involved.

The Broader Evidence Base for Niagen NR

The Bergen study adds to a body of research on Niagen® NR that is the most extensive in the newer NAD+ precursor category.

• 40+ peer-reviewed, published clinical studies that have been conducted on Niagen NR—spanning aging, cellular health, cardiovascular health, muscle health, neurological health, immune health, and metabolic health.
• 500+ human studies support NR overall, 75% of which used Niagen as the form of NR studied.
• 300+ global research collaborations have been conducted through Niagen Bioscience’s External Research Program, supplying quality-tested Niagen to leading universities and research institutions worldwide.
• A USP Monograph for NR Chloride is forthcoming—a first for NR, representing a significant regulatory and quality credibility milestone.
• Niagen holds FDA GRAS (Generally Recognized as Safe) status, having been reviewed twice under the FDA's New Dietary Ingredient notification program.

This is what it means for a supplement to be backed by science—not marketing-led claims, but a sustained and growing body of independent, peer-reviewed, published human evidence.

Interested in NAD+ Supplements? Here’s What This Means for You

If you're currently taking NMN, or considering it, the data from the Bergen study is worth understanding. At the same dose, independent researchers found NR to produce more than twice the NAD+ elevation—and found the difference significant enough to discontinue NMN from their research program entirely.

If you're taking Tru Niagen, you're taking the exact form of NR the Bergen researchers chose to use. Not because we supplied it—they bought it themselves. That is meaningful.

And if you're trying to make sense of a crowded, often confusing supplement category, the clearest guidance remains: follow the clinical evidence. NR has it. The Bergen study just added the most direct human comparison yet.

Ready to try the most-studied and patented NAD+ precursor supplements?

Tru Niagen is powered by Niagen NR—the form used by independent researchers worldwide, and the same form trusted by healthcare practitioners, leading experts, and professional athletes.

Shop Tru Niagen

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Study results described are from independent peer-reviewed research. Niagen Bioscience was not a sponsor of the Berven et al. study. Researchers independently purchased Tru Niagen commercially.