Urolithin A · Nutrient Desk

Editorial draft with source-based evidence review. Final clinical sign-off is pending.

A gut metabolite that influences mitophagy

Urolithin A forms when certain gut bacteria convert plant compounds from pomegranates, walnuts or berries. These foods contain ellagitannins or ellagic acid as precursors. How much urolithin A is made from them varies from person to person. Review

The compound draws interest mainly because of its effect on mitophagy, the process cells use to break down damaged mitochondria. Animal experiments and early human studies have produced positive findings here. Whether taking it keeps people healthy for longer cannot yet be answered from this work. The clinical results so far mostly concern individual muscle tests and biological markers.

Chemistry: from ellagic acid to dibenzopyranone

Chemically, urolithin A belongs to the family of dibenzo[b,d]pyran-6-one compounds. Other members include urolithins B, C, D and G. They differ in the number and position of their hydroxyl groups, so the substances are not biologically interchangeable.

Urolithin G was chemically identified in a study with human gut bacteria of the genus Enterocloster and was also detected in stool samples after pomegranate extract. Work like this helps clarify the conversion pathways. It does not produce a ranking in which urolithin A would be the strongest member of the family for every biological effect. Study

From traditional use of pomegranate to mitophagy research

Ellagitannins first release ellagic acid. Several gut bacteria can then work together to form urolithins. Studies with isolated bacteria and co-cultures show how different urolithin profiles arise. Microbiology study

An important starting point for current research was a 2016 paper: urolithin A stimulated mitophagy, extended the lifespan of the roundworm C. elegans and improved physical performance in rodent models. That made the substance interesting for further studies in humans. Preclinical study

The conversion of plant compounds does not depend only on the food eaten. A systematic review describes influences from the gut microbiome, age, sex and other individual factors. Eating a given food therefore does not deliver the same amount of metabolite in everyone. Review

Urolithin A: From gut conversion to mitochondrial quality control

Mitochondria are constantly renewed. Mitophagy removes damaged or no longer needed mitochondria; making new ones is a separate process coordinated with it. Disturbances in this quality control are studied in connection with aging and various diseases. That makes it a possible therapeutic target, but not every change in a marker involved already means a health benefit. Mechanistic review

Mechanism: activation of mitophagy in cells, rodents and humans

In preclinical models, urolithin A influences mitophagy signaling pathways, including PINK1-dependent processes. Experiments like these make it possible to study individual steps of cell biology. Their results, however, cannot be carried over directly to optimal intake or disease treatment in humans. Preclinical work

“More mitophagy” is not an open-ended health goal either: a review of nerve cell biology describes both protective functions and possible problems from excessive activation. What matters is the tissue and its condition. Review

Experiments on muscle cells show time-dependent changes in markers of mitophagy and energy metabolism. A first human study found changes in blood acylcarnitines and in mitochondrial gene expression in muscle after four weeks of intake. That supports biological plausibility. These measurements, however, are not direct proof that the whole body clears damaged mitochondria faster or ages more slowly. Cell study Human study

Pharmacokinetics: oral bioavailability and dependence on the microbiome

After direct urolithin A is taken, the compound and its metabolites can be detected in the blood. This bypasses the bacterial step of making it from dietary precursors. Formulation and further processing in the body still affect exposure. Human study Review

In a study of 100 healthy adults, about 40 percent produced clearly measurable urolithin A after drinking pomegranate juice. A direct dose of 500 mg produced higher and more consistent exposure. These are results under the conditions of this study, not a statement that the others are fundamentally unable to make urolithin A. Study

A study of ellagic acid packaged in milk exosomes found sex-dependent differences in mice. This particular formulation and animal population do not yet support any corresponding intake recommendations for women or men. Animal study

What research on urolithin A shows

The most useful distinction is between three levels: biological mechanisms, measurable functions such as strength or walking ability, and longer-term health outcomes. Urolithin A has produced interesting results on the first two levels. The studies are mostly small and short, and positive and unchanged endpoints differ.

The following sections therefore describe the population studied, the result and its limitations in each case. A blanket rating based only on the number or size of studies would hide these differences.

What human studies show about mitochondrial markers

The first human study mainly examined safety and tolerability. After four weeks of 500 or 1,000 mg daily, it also found changes in acylcarnitines and in mitochondrial gene expression in muscle. Study

Later studies also saw changes in selected metabolic and inflammatory markers. In older adults, lower acylcarnitine, ceramide and CRP levels than with placebo were observed after four months, among other findings. These results are useful for further research; on their own they prove neither disease prevention nor a need for a supplement. Study

Muscle function in older and middle-aged adults

A four-month study of 66 older adults, with an average age of 71.7 years, tested 1,000 mg daily. Endurance of individual hand and leg muscles improved after two months compared with placebo. The primary endpoints (the 6-minute walk distance and maximal ATP production in the hand muscle), however, did not differ significantly after four months. Study

The ATLAS study followed 88 inactive middle-aged adults for four months on 500 or 1,000 mg daily. Strength of the hamstring muscles improved: the relevant measure rose by about 12 and 9.8 percent from baseline in the two groups, a significant difference from placebo. Grip strength and body composition did not clearly improve. The primary endpoint, peak power output, was not significantly better either. Oxygen uptake and walking distance showed positive changes within the higher-dose group, but no statistically clear advantage over placebo. Manufacturer funding and several authors’ ties to the company are part of the context for this exploratory study. ATLAS full text

A 2026 meta-analysis pooled five small studies. The pooled walking distance showed a positive but not statistically clear difference, with low certainty of evidence. Other muscle findings could not be meaningfully combined because the methods differed. Positive individual results remain interesting, but they need larger confirmatory studies. Meta-analysis

Urolithin A and cellular, immune and cardiovascular endpoints in aging: limited

A 2025 randomized study looked at 50 healthy middle-aged adults who took 1,000 mg daily or placebo for four weeks. Urolithin A changed the composition and metabolism of certain immune cells, including CD8 T cells. This is an early human finding on immune biology; it does not demonstrate fewer infections or better cancer treatment. Study

In earlier experiments with mice and treated T cells, certain anti-tumor responses improved. That gives rise to a research hypothesis for immunotherapies, not a recommendation to take it on your own during cancer treatment. Preclinical study

A cardiovascular paper linked positive animal findings with an analysis of ceramides from a human study. Lower levels of such risk markers are not the same as fewer heart attacks or a proven treatment for heart failure. Study

Urolithin A is thus one of several nutrition-related approaches to mitochondrial health. Exercise remains a central part of research and care for muscle function in older age. Review

Urolithin A extends lifespan or reverses aging in humans: animal studies only

The lifespan extension in C. elegans is a preclinical finding. The human studies discussed here were not designed to show a longer lifespan. A change in immune cells or mitochondrial markers does not automatically mean biological age is being turned back, either. Whether this leads to a long-term health benefit remains an open research question. Original preclinical study

Urolithin A improves athletic performance in healthy young athletes: limited

A single-blind pilot study looked at 20 male youth soccer players with an average age of 17.5 years. During preseason training, they took 1,000 mg or placebo daily for six weeks. There were advantages in the Yo-Yo endurance test and in jump height; sprint speed and several other measures did not differ. The small sample and wide uncertainty intervals limit what can be concluded. The results justify further studies, but not a general recommendation for adolescents or athletes to take it. Pilot study

Overall, there are interesting findings on function and markers so far, but no evidence from these studies that urolithin A prevents or treats sarcopenia, Alzheimer’s disease or osteoarthritis in humans. A supplement does not replace appropriate training or a medical workup of symptoms.

Direct urolithin A vs. precursor sources: why the form matters

Direct urolithin A and a pomegranate extract supply different starting compounds. Higher urolithin A exposure, however, does not yet answer which option is more beneficial to health in the long run.

Direct urolithin A: It bypasses bacterial conversion from ellagitannins. Several clinical studies used the specific formulation Mitopure from Amazentis. The results apply to the product and dose studied in each case.
Ellagic acid or ellagitannin extracts: Gut bacteria can make urolithins from these. The amount and timing differ between people, so an extract cannot be equated dose for dose with pure urolithin A.
Walnuts, pomegranates and berries: Besides the precursors, they supply other nutrients and plant compounds. Their nutritional value does not depend on reaching a particular urolithin A concentration. Review of metabolic differences

For a supplement, a clear statement of the amount, verifiable identity and independent batch testing are more useful than big promises. A quality test, however, does not confirm medical efficacy. Combination products also make it harder to attribute a possible effect or side effect.

Regulatory status of urolithin A

In its response to GRAS Notice 000791, the FDA said it had no questions about the notifier’s safety assessment under the described conditions of use in food. It also made clear that this is not its own formal GRAS determination under that procedure. In particular, the letter is not a drug approval and not proof of any benefit against disease. FDA letter

In the EU, safety assessment and authorization are separate steps: EFSA (the European Food Safety Authority) assesses, and the European Commission and member states decide on authorization. An application from Amazentis for urolithin A is documented from 2018. An application alone does not prove that authorization has been granted. Whether a specific product may be sold depends on the current Union list and the conditions set out in it. Application Authorization procedure Union list

Safety and drug interactions of urolithin A

Overall, the studies discussed report favorable short-term tolerability in the groups examined. The multi-month studies with 500 or 1,000 mg daily are the most relevant. They cannot, however, reliably assess rare side effects, intake over years or safety in complex medical conditions.

It is also important to distinguish between a theoretical consideration from cell biology and a clinically proven drug interaction.

Reported side effects in urolithin A studies

The first human study tested single doses and four weeks of daily intake; safety was its primary goal. The reported tolerability was favorable. Study

In the four-month study in older adults, adverse events did not differ statistically between urolithin A and placebo. ATLAS also found no meaningful differences in its safety assessments. Some of the complaints reported there were related to the muscle biopsies taken for research. For rare risks, or risks that only appear after longer intake, the studies so far are too small and too short. Study in older adults ATLAS

Interactions with urolithin A

For the following combinations, the sources discussed do not allow a reliable classification as a “minor” or “moderate” clinical interaction:

Statins and metformin: The fact that drugs and urolithin A can both influence mitochondrial processes does not tell you whether the combination is harmful, helpful or has no relevant effect.
Antiretroviral drugs: A shared link to mitochondrial biology is no substitute for studying the specific drugs and doses.
Immunosuppressants or cancer therapies: The experimental T-cell findings make this question scientifically interesting. Clinical tolerability or efficacy of the combination cannot be inferred from them. Preclinical T-cell study

If you take medication regularly, have the specific combination checked by a doctor or pharmacist beforehand. Do not stop prescribed medication in order to take a supplement.

Pregnancy, breastfeeding and special populations

For pregnancy and breastfeeding, the human studies reviewed here do not provide enough safety data. Additional intake should therefore not happen without an explicit professional recommendation.

For liver or kidney disease and diagnosed mitochondrial disorders, studies in mostly healthy people translate only to a limited extent. A safe dose adjustment cannot be calculated from metabolic pathways alone.

The small soccer study also included adolescents. It is not enough to assess the safety of routine intake in children and adolescents. Pilot study

Who should avoid urolithin A?

Particular caution makes sense in the following cases:

Pregnancy and breastfeeding, because reliable human safety data are lacking.
Children and adolescents, for whom the available data do not support a general supplementation recommendation.
Significant organ disease or complex drug therapy, as long as individual suitability has not been clarified.
A known allergy to an ingredient of the specific product.

A pomegranate allergy is not automatically an allergy to chemically manufactured urolithin A. What matters are the actual ingredients, possible residues and your personal allergy situation. The synthetic manufacture of the substance described in the FDA dossier is documented. FDA dossier response

Why urolithin A production from food varies

Not everyone makes the same amount of urolithin A from the same serving of a food. That does not imply a general deficiency, though, nor that most people would need a supplement. The roughly 40 percent of clear producers come from the juice study described above and should not be read as a fixed limit for all adults. Study

Substance: Direct supplements deliver urolithin A; foods and precursor extracts deliver compounds from which it can form.
Uptake: Direct intake bypasses the bacterial production step. How your body processes it individually still matters.
Benefit: There are small clinical studies on direct supplements. Foods supply other nutrients and should not be judged only by their urolithin A yield.
Dose: A supplement amount cannot be reliably converted into a universal serving of walnuts or pomegranate.
Safety and regulation: Familiar foods, concentrated extracts and isolated substances are different products and have to be assessed accordingly.
Cost: Prices depend on the product and the amount. A higher price does not prove a better effect.

A special urine or microbiome test is not an established prerequisite for deciding on a supplement. Research evidence that the metabolite is formed does not yet answer whether taking it would benefit your health.

Which measurements make sense in everyday life

The measures used in studies are not a ready-made monitoring plan for everyday life. Before-and-after values can describe changes, but on their own they cannot rule out a placebo effect, training effects or natural fluctuations.

CRP or hs-CRP: Inflammatory markers can change for many reasons. The study findings do not make them a specific test of how urolithin A is working for you personally.
Muscle strength and walking ability: Functional tests can be clinically useful if you have symptoms. Which tests fit depends on the question; grip strength is not the same as the hamstring strength that improved in ATLAS.
Body composition: A DXA scan is not a routinely needed supplement test. ATLAS showed no corresponding improvement in lean mass.
Acylcarnitines: They were studied as research markers, not as a validated individual target range for intake. First human study
Lactate and exercise tests: They answer specific medical or sports science questions, but do not prove any general “mitochondrial optimization” from a capsule.
Urolithin A measurements: They can capture exposure. The studies discussed do not yield a clinically grounded threshold above which everyone should supplement.

If you notice a change in your physical capacity, your symptoms and everyday function are the starting point for a medical assessment. A broad lab panel is not automatically needed for that.

When symptoms call for a medical workup, not a supplement

Unexplained muscle weakness, persistent fatigue or a markedly reduced capacity for exertion should first be assessed by a doctor. Medical history and examination determine whether, for example, blood tests, an evaluation of sleep problems or a physiotherapy assessment make sense.

Research on urolithin A raises interesting questions. For people with symptoms, though, the first priority is to identify a treatable cause and find a suitable exercise or treatment plan.

Frequently asked questions

What is urolithin A?

A metabolite made by certain gut bacteria from ellagic acid and ellagitannins, which occur in pomegranates, walnuts and berries, among other foods. In experimental models, it influences processes of mitochondrial quality control. How much an individual makes from food varies.

What is urolithin A used for?

Supplements are marketed for muscle function and healthy aging. Small studies report benefits in individual strength or endurance tests as well as changes in biological markers. So far, this does not establish prevention of age-related diseases.

What dose of urolithin A was used in studies?

The two four-month adult studies discussed tested 500 or 1,000 mg daily; the study in older adults used 1,000 mg. These are study doses, not a general recommendation. Formulation, target group and length of follow-up are part of the context.

What are the side effects of urolithin A?

In the short studies discussed, tolerability was favorable overall; there was no clear difference in adverse events compared with placebo. Rare problems, long-term effects and safety in complex medical conditions are therefore not sufficiently clarified.

Is urolithin A FDA-approved?

The FDA’s GRAS response letter concerns specific conditions of use in food and is not an approval to treat disease. The fact that a supplement is available does not mean regulators have confirmed that it works, either.

Can I get urolithin A from pomegranate or walnuts instead?

Your gut microbiome can convert their precursors into urolithins. How much is produced varies. Regardless of that, these foods remain valuable parts of a varied diet; no fixed equivalence with a supplement dose can be given.

Who should avoid urolithin A?

In pregnancy, while breastfeeding, in childhood, with significant organ disease or with complex drug therapy, use should be clarified with a professional. The existing studies do not allow a comprehensive safety assessment for these groups. If you have an allergy, the actual product ingredients are what count.

What blood tests should I have before trying urolithin A?

No routine lab panel is established. Research markers such as acylcarnitines or CRP cannot reliably predict whether you will benefit. If weakness or fatigue is the reason, a medical examination should decide which tests make sense.

Sources and literature

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Beltrán D, Frutos-Lisón MD, García-Villalba R, Yuste JE, García V, Espín JC, Selma MV, Tomás-Barberán FA (2023). NMR Spectroscopic Identification of Urolithin G, a Novel Trihydroxy Urolithin Produced by Human Intestinal Enterocloster Species. Journal of agricultural and food chemistry, 71(31), 11921-11928. https://doi.org/10.1021/acs.jafc.3c01675
Iglesias-Aguirre CE, García-Villalba R, Beltrán D, Frutos-Lisón MD, Espín JC, Tomás-Barberán FA, Selma MV (2023). Gut Bacteria Involved in Ellagic Acid Metabolism To Yield Human Urolithin Metabotypes Revealed. Journal of agricultural and food chemistry, 71(9), 4029-4035. https://doi.org/10.1021/acs.jafc.2c08889
Ryu D, Mouchiroud L, Andreux PA, Katsyuba E, Moullan N, Nicolet-Dit-Félix AA, Williams EG, Jha P, Lo Sasso G, Huzard D, Aebischer P, Sandi C, Rinsch C, Auwerx J (2016). Urolithin A induces mitophagy and prolongs lifespan in C. elegans and increases muscle function in rodents. Nature medicine, 22(8), 879-88. https://doi.org/10.1038/nm.4132
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Andreux PA, Blanco-Bose W, Ryu D, Burdet F, Ibberson M, Aebischer P, Auwerx J, Singh A, Rinsch C (2019). The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humans. Nature metabolism, 1(6), 595-603. https://doi.org/10.1038/s42255-019-0073-4
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Denk D, Singh A, Kasler HG, D’Amico D, Rey J, Alcober-Boquet L, Gorol JM, Steup C, Tiwari R, Kwok R, Argüello RJ, Faitg J, Sprinzl K, Zeuzem S, Nekljudova V, Loibl S, Verdin E, Rinsch C, Greten FR (2025). Effect of the mitophagy inducer urolithin A on age-related immune decline: a randomized, placebo-controlled trial. Nature aging, 5(11), 2309-2322. https://doi.org/10.1038/s43587-025-00996-x
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Monsalve Acevedo A, Sanctuary C, Aitken RJ, Wilkins A, Harrison N, Naughton M (2025). Effects of Urolithin A supplementation on performance and antioxidant status in academy soccer players during preseason: a pilot randomised controlled trial. Frontiers in nutrition, 12, 1674446. https://doi.org/10.3389/fnut.2025.1674446
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Origin and editorial review status

Prepared for Nutrient Desk from the source article. Source identity and key claims were checked against abstracts, selectively read original full texts and regulatory documents. Not all full texts were accessible; final clinical sign-off is pending. The draft remains excluded from indexing.