What it is
Urolithin A is not a peptide, and it is included here because it comes up constantly alongside the mitochondrial compounds this site tracks. It is a metabolite, meaning the body does not absorb it directly from food. Gut bacteria produce it from ellagitannins, compounds found in pomegranate, walnuts and certain berries.
That production step is the compound's defining problem, and it is covered in its own section below.
Mechanism under study
Research on Urolithin A centres on mitophagy, the process by which a cell identifies damaged mitochondria and recycles them. Mitophagy declines with age in animal models, and the proposed effect is that Urolithin A restores some of that clearance capacity rather than stimulating energy production directly.
This places it upstream of the outcomes people associate with it. The literature describes changes in mitochondrial biomarkers and in muscle function, not in subjective energy.
Human research
Urolithin A has more randomised human data behind it than most compounds discussed in the same conversation, which is the main reason it appears on this site at all.
A randomised clinical trial in older adults, published in JAMA Network Open in 2022, examined four months of supplementation and reported improvements in muscle endurance and in biomarkers of mitochondrial health. A separate randomised trial in middle-aged adults, published in Cell Reports Medicine the same year, reported improvements in muscle strength and exercise performance. Earlier first-in-human work established a safety and bioavailability profile in elderly participants.
The reported effects are consistent in direction and modest in size. The trials measured muscle endurance, strength and blood biomarkers. None of them measured everyday fatigue in otherwise healthy adults, which is the outcome most readers are actually asking about.
The converter problem
Only a minority of people produce meaningful amounts of Urolithin A from food, because the conversion depends on gut bacteria that not everyone carries. Published estimates commonly place efficient converters at roughly a third to 40% of the population, and the figure varies by population studied.
This is the argument for supplementing the finished compound rather than eating pomegranate, and it is unusually well-founded compared with most supplement rationales. It is also worth noting that it means dietary intake is a poor proxy, so no one should assume they are already covered.
Where it sits relative to the compounds on this site
Urolithin A is the outlier among the mitochondrial compounds. It requires no reconstitution, no research-vendor account and no injection, and it carries more randomised human evidence than MOTS-c or SS-31. What it does not carry is a per-milligram market, so it cannot be price-compared the way the rest of this catalogue can.
For how the three are usually sequenced, see what order actually makes sense.
Availability
Urolithin A is sold as a standard retail supplement rather than through research-peptide vendors, so it does not appear in the per-mg comparison tool and this page carries no price range. Timeline's Mitopure is the branded form used in most of the human trials referenced above, which makes it the straightforward default for anyone who would rather not evaluate unfamiliar listings. See it on Amazon ↗
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