Evidence explainerUrolithin A
Urolithin A: What the Trials Show, and How Label Doses Compare With Studied Doses
Urolithin A is the gut-microbe compound behind a wave of longevity supplements. Human trials show modest gains in muscle endurance and some strength measures, but several primary endpoints were missed, most trials were funded by one maker, and most used 1,000 mg a day.
Key takeaways
- In 66 adults aged 65 to 90, 1,000 mg/day for 4 months improved hand and leg muscle endurance, but the primary endpoints, 6-minute walk and peak muscle ATP production, did not differ from placebo [2].
- In middle-aged adults, 500 or 1,000 mg/day for 4 months improved leg strength by about 12%, while peak power output, the primary endpoint, did not improve significantly [3].
- In a 4-week trial of 42 highly trained male runners, 1,000 mg/day did not improve 3,000 m time-trial performance (run by 22 of them), though perceived exertion and a muscle-damage marker fell [5].
- Trials reported no safety signal; the longest lasted 4 months [1][2].
- Most positive human trials used 1,000 mg/day; the lowest studied dose is 500 mg/day [3][2][6].
Safety at a glance
From our Urolithin A monograph. Published interactions and cautions only, each with its source.
Who should be careful
- Medicines. No published drug interactions for urolithin A were found in our sources. That is an absence of data, not proof of safety with every medicine.[1][2]
- Pregnancy and breastfeeding. No trials in pregnancy or breastfeeding in our sources.[1]
- Long-term use. The longest trials lasted 4 months, so longer-term safety has not been studied.[2][3]
- Industry funding. The 4-month older-adult and middle-aged trials were funded by the maker of a branded form; independent replication is limited.[2][3]
The evidence, graded
Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.
- Grade CImprovedMuscle endurance in older adultsHand and leg muscle endurance (contractions to fatigue) improved more than placebo at 2 months; CRP, acylcarnitines and ceramides fell. The primary endpoints, 6-minute walk distance and maximal muscle ATP production, did not differ from placebo.
- Grade CImprovedMuscle strength and endurance in middle-aged adultsLeg muscle strength improved about 12% vs placebo; peak VO2 and 6-minute walk improved, CRP fell. Peak power output, the primary endpoint, did not improve significantly.
- Grade DMixedStrength and repetitions in trained menIsometric strength and repetitions to failure improved vs placebo; 1-rep max bench and squat did not differ significantly.
- Grade CNo effectRunning performance and recovery3,000 m time trial did not improve vs placebo. Perceived exertion and post-exercise creatine kinase (a muscle-damage marker) were lower with urolithin A.
- Grade CImprovedImmune-cell compositionNaive-like CD8+ T cells and their fat-burning capacity increased vs placebo; NK-cell and monocyte subsets also shifted. Cytokine changes were secondary outcomes.
What urolithin A is
Urolithin A is made by gut bacteria from ellagitannins in foods such as pomegranates and walnuts [7]. People differ in which urolithins their microbiome produces, and some produce little or none, which is the rationale for taking it directly [7]. In a first-in-human trial in sedentary older adults, it was bioavailable at all doses tested, had a favorable safety profile, and 500 and 1,000 mg/day for 4 weeks shifted muscle mitochondrial gene expression and blood acylcarnitines [1].
Scorecard: what the trials found
Arrows are from your point of view: ↑ means the outcome improved versus placebo, ↔ means no clear difference [2][3][4][5][6]:
- ↑ Hand and leg muscle endurance in adults aged 65 to 90, 1,000 mg/day for 4 months; ↔ 6-minute walk and peak ATP production, grade C [2].
- ↑ Leg strength (about 12%) in middle-aged adults, 500 or 1,000 mg/day for 4 months; ↔ peak power output, grade C [3].
- ↑ Isometric strength and repetitions to failure, ↔ 1-rep max, in 20 trained men, 1,000 mg/day for 8 weeks, grade D [4].
- ↔ 3,000 m time trial in highly trained male runners (22 of the 42 enrolled ran it), 1,000 mg/day for 4 weeks, grade C [5].
- ↑ More naive-like, less exhausted CD8+ T cells in 50 middle-aged adults, 1,000 mg/day for 4 weeks (lab markers, not infections), grade C [6].
Caveats that matter
Primary endpoints were missed in the two longest trials: 6-minute walk and peak ATP production in older adults, and peak power in middle-aged adults [2][3]. The headline gains come from secondary outcomes [2][3].
Funding and authorship are concentrated. The older-adult, middle-aged and runner trials disclosed employees or board members of Amazentis, the maker of the branded form Mitopure, and the runner trial was funded by it [2][3][5]. Independent replication is limited; the 8-week trial in trained men reported no conflicts but enrolled only 20 people [4].
The immune trial measured cell populations and function in the lab over 4 weeks, not illness rates [6].
Label dose versus studied dose
Studied doses run from 500 to 1,000 mg/day for 4 weeks to 4 months, and most trials used 1,000 mg/day [1][2][3][5][6]. The urolithin A capsule listed on this page provides 500 mg per 2-capsule serving, which matches the lower dose arm of the middle-aged trial but is half the dose used in the older-adult, runner, trained-men and immune trials [3][2][4][5][6]. Its product page says it is derived from pomegranate extract; the middle-aged trial tested a branded form (Mitopure), and we have not independently tested any product's purity [3].
Eating pomegranate or walnuts is not a substitute for a known dose, because how much urolithin A your gut makes depends on your microbiome [7]. For other longevity compounds checked against trials see does NMN work and spermidine: what the trials show; the dose table and safety notes are in the urolithin A monograph.
Quick answers
What dose of urolithin A was used in studies?
500 to 1,000 mg a day, for 4 weeks to 4 months; most trials used 1,000 mg/day [2][3][6].
Does urolithin A build muscle?
It improved endurance and some strength measures in older and middle-aged adults, but primary endpoints such as 6-minute walk and peak power were not met [2][3].
Is urolithin A safe?
Trials up to 4 months reported no difference in adverse events versus placebo; longer-term safety has not been studied [2].
Can I get urolithin A from pomegranate?
Only if your gut bacteria convert ellagitannins to it, and people differ in which urolithins they produce [7].
Keep reading
Full monographs
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Where to buy Urolithin A
Products from brands we partner with that contain Urolithin A. Listing a product is not a claim that it works; check the amount per serving against the doses studied above, and the label for other ingredients.
- SupersmartPaid linkUrolithin A2 capsules: 500 mg urolithin A (from pomegranate extract), the lower of the 500–1,000 mg/day doses studied; most trials used 1,000 mg/day; 30 servingsShop at Supersmart (opens in new tab)Price and label checked 2026-10-12 on the brand’s site.
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References
- [1]The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humans. Nature Metabolism, 2019.
- [2]Effect of Urolithin A Supplementation on Muscle Endurance and Mitochondrial Health in Older Adults: A Randomized Clinical Trial. JAMA Network Open, 2022.
- [3]Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomized trial in middle-aged adults. Cell Reports Medicine, 2022.
- [4]Assessment of Urolithin A effects on muscle endurance, strength, inflammation, oxidative stress, and protein metabolism in male athletes with resistance training: an 8-week randomized, double-blind, placebo-controlled study. Journal of the International Society of Sports Nutrition, 2024.
- [5]Evaluating the Impact of Urolithin A Supplementation on Running Performance, Recovery, and Mitochondrial Biomarkers in Highly Trained Male Distance Runners. Sports Medicine, 2025.
- [6]Effect of the mitophagy inducer urolithin A on age-related immune decline: a randomized, placebo-controlled trial. Nature Aging, 2025.
- [7]The gut microbiota metabolism of pomegranate or walnut ellagitannins yields two urolithin-metabotypes that correlate with cardiometabolic risk biomarkers: Comparison between normoweight, overweight-obesity and metabolic syndrome. Clinical Nutrition, 2018.