New human study: NMN increases NAD⁺ in humans, and the gut microbiome appears to play a key role
In January 2026, an interesting new human study was published in the scientific journal Nature Metabolism. The researchers compared three well-known NAD⁺ precursors:
- NMN (Nicotinamide Mononucleotide)
- Nicotinamide Riboside (NR)
- Nicotinamide (NAM / vitamin B3)
The results provide new insights into how these substances affect NAD⁺ metabolism in humans, and suggest that the gut microbiome may play a much larger role than previously thought.
Why is NAD⁺ important?
NAD⁺ (nicotinamide adenine dinucleotide) is an essential coenzyme involved in:
- cellular energy production
- mitochondrial function
- DNA repair
- oxidative stress response
- sirtuin activity
- healthy aging
NAD⁺ levels gradually decline with age. That is why there is a lot of scientific interest in substances such as NMN and NR that can support the body in maintaining healthy NAD⁺ levels.
Study design
The study examined healthy adults who were given one of the following substances for 14 days:
- NMN (500 mg per day)
- NR (500 mg per day)
- nicotinamide (500 mg per day)
- placebo
In addition, the researchers analyzed:
- blood levels of NAD⁺-related metabolites
- microbial conversion in the gut
- differences in metabolic pathways
The goal was not only to see whether NAD⁺ increased, but especially how this happens.
What did the researchers find?
1. Both NMN and NR increased NAD⁺ in humans
One of the study’s key conclusions:
Both NMN and NR significantly increased NAD⁺-related biomarkers in the blood.
The effects of NMN and NR were largely comparable.
This supports earlier indications that oral NMN is biologically active in humans.
2. The gut microbiome appears to play an important role
Perhaps even more interesting was the discovery that gut bacteria are likely involved in the conversion of NMN and NR.
The researchers saw indications that:
- NMN and NR are partly converted into nicotinic acid (niacin)
- after which the body rebuilds NAD⁺ again via the so-called Preiss-Handler pathway
This suggests that:
- oral NMN may not be absorbed solely “directly”
- but partly works via microbial and metabolic conversion
This is scientifically important, because for years there has been debate about:
- the absorption of NMN
- stability in the gastrointestinal tract
- differences between NMN and NR
This study shows that reality is likely more complex than a simple “absorption or breakdown” debate.
What does this mean for NMN supplementation?
This study is especially important because it reinforces three things:
1. Mechanistic plausibility
The results support that oral NMN does indeed influence NAD⁺-related processes in humans.
2. New insights into absorption and metabolism
The gut microbiome may play a key role in how NAD⁺ boosters work.
3. Support for further research
The study helps explain why some people may respond more strongly to NAD⁺ precursors than others.
Our vision
At EnduraVita we closely follow new scientific developments around NMN, NAD⁺ and healthy aging.
Although research into NAD⁺ precursors is still very much in development, studies like this contribute to a better understanding of:
- cellular energy
- mitochondrial health
- aging mechanisms
- the complex interaction between nutrition, metabolism and the microbiome
Reference/source:
Christen S. et al.
“The differential impact of three different NAD⁺ boosters on circulatory NAD and microbial metabolism in humans.”
Nature Metabolism (2026)
DOI: 10.1038/s42255-025-01421-8
PubMed: PubMed 41540253
