⚕️ Medical Disclaimer
⚕️ Medical Disclaimer: Educational content only. Urolithin A products are not a treatment for sarcopenia, mitochondrial disease, or aging. Talk to a clinician before using any supplement.
What Urolithin A Is (And Is Not)
Urolithin A is a gut-microbiome metabolite of ellagitannins found in foods such as pomegranate and walnuts. It is a small molecule, not a peptide. CalcMyPeptide keeps an identity leaf at /peptides/urolithin-a because people search it next to mitochondrial peptides — and then try to put it in a reconstitution calculator. Do not. There is no BAC-water chart.
It is not MOTS-c. It is not SS-31 / elamipretide. Those are peptide identities with different evidence bodies. Urolithin A’s research hook is mitophagy: selective clearance of damaged mitochondria.
Mitophagy and Muscle Aging — From Sources We Opened
Aging skeletal muscle is associated with declining mitochondrial quality. One proposed contributor is reduced mitophagy — the cell’s ability to remove dysfunctional mitochondria. Urolithin A has been studied as an oral mitophagy activator in animals and in human supplement trials.
Andreux et al. (Nature Metabolism, 2019) reported that urolithin A was safe and bioavailable in older humans and induced a molecular signature consistent with improved mitochondrial and cellular health. That first-in-human safety/biomarker paper is the bridge between the animal mitophagy story and later muscle-performance trials.
Liu et al. (JAMA Network Open, 2022; PMID 35050355) ran a double-blind, placebo-controlled randomized trial in adults aged 65–90. Participants received 1,000 mg/day oral urolithin A (Mitopure softgels) or placebo for four months. The trial assessed muscle endurance, six-minute walk distance, plasma biomarkers, and muscle ATP production by magnetic resonance spectroscopy. Muscle endurance in hand and leg muscles improved with urolithin A relative to placebo in that analysis; six-minute walk distance and maximal ATP production did not show significant improvement. Read that as a mixed, endpoint-specific result — not a blanket “reverses muscle aging” claim.
Singh et al. (Cell Reports Medicine, 2022; PMID 35584623; NCT03464500) randomized untrained middle-aged adults to placebo, 500 mg, or 1,000 mg urolithin A daily for four months. Muscle strength improved about 12% with urolithin A in that report. The authors described clinically meaningful improvements on VO₂ peak and six-minute walk performance, while the primary endpoint of peak power output did not improve significantly. Muscle biopsies showed increased proteins linked to mitophagy and mitochondrial metabolism. Again: secondary and biomarker signals can move while a primary power endpoint does not.
How to Read These Trials Without Turning Them Into a Protocol
Studied oral doses in the opened RCTs cluster at 500–1,000 mg/day for about four months. Those are trial conditions under branded softgel products, not a DIY powder protocol and not medical advice.
Endpoints matter. Endurance and strength markers can improve while walk distance, ATP by MRS, or peak power stay flat. Anyone selling urolithin A as a guaranteed sarcopenia drug is ahead of the evidence.
Product identity still matters. Supplement SKUs are not research peptides, but purity, dose accuracy, and labeling still vary. Compare the bottle to the trial product only when the label actually matches.
Where It Fits Next to Mitochondrial Peptides
If your question is “mitophagy oral ingredient,” urolithin A is the leaf. If your question is “mitochondrial ORF peptide,” see MOTS-c. If your question is “cardiolipin-binding peptide,” see SS-31. Different molecules. Different routes. Different evidence limits.
For NAD+ precursor literacy — another longevity aisle that is also not a peptide — see our NMN leaf and the NAD+ peptides longevity stack essay.