IngredientsUrolithin A is a dibenzo-α-pyrone derivative with the systematic IUPAC name 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one, characterized by a coumarin core structure featuring hydroxyl groups at positions 3 and 8. Its molecular formula is C₁₃H₈O₄, and it has a molecular weight of 228.20 g/mol. Its CAS number is 1143-70-0, and its recognized synonyms include 2′,7-Dihydroxy-3,4-benzocoumarin and 3,8-Dihydroxy Urolithin.
Urolithin A belongs to the class of organic compounds known as benzo-coumarins or dibenzo-α-pyrones, characterized by a polycyclic aromatic structure with a 1-benzopyran moiety and a ketone group at the C2 carbon atom. Structurally, urolithins share a tricyclic lactone backbone, with variations in hydroxylation accounting for their chemical diversity. In pure form, the compound is a crystalline solid. Its solubility profile includes DMF at 30 mg/ml and DMSO at 30 mg/ml, with only slight solubility in ethanol and very limited solubility in aqueous PBS.
Urolithin A belongs to the broader class of urolithins, which are metabolites produced by the gut microbiota from ellagitannins and ellagic acid; it represents a downstream transformation product of ellagic acid (C₁₄H₆O₈), involving microbial decarboxylation and lactone ring formation. Urolithin A is the predominant isoform of urolithins found in plasma and urine following the consumption of ellagitannins (ETs) and ellagic acid (EA).
Urolithin A is not present as such in any food; it is exclusively produced endogenously through gut microbial biotransformation. Ellagitannins (ETs) and ellagic acid (EA), the dietary precursors of urolithins, are natural dietary polyphenols found in various fruits and nuts, including walnuts, raspberries, strawberries, pomegranates, and many tropical fruits.
These dietary precursors are found in a variety of fruits and berries — pomegranates, strawberries, raspberries, blackberries, and camu-camu — as well as in nuts including walnuts, hazelnuts, acorns, chestnuts, and pecans; they also occur in muscadine grapes and in medicinal plants and tisanes such as geranium and oak leaves. Products produced from these foods, such as juices, jellies, oak-aged wines, and spirits, also contain ellagitannins.
Urolithin A is not directly found in food sources; rather, its presence in the body is contingent upon the individual's gut microbiota, which varies significantly among individuals. Ellagitannins are extensively metabolized and the absorption of their hydrolysis product, ellagic acid, is also very limited due to its hydrophobic structure; thus, the beneficial effects of ellagitannin-containing foods are likely attributable to ellagic acid-derived metabolites — namely urolithins — that are generated by the gut microbiota.
Urolithin A is produced through a multi-step microbial biosynthesis pathway in the human gut microbiota, starting from ellagic acid, which is released from dietary ellagitannins. The process involves initial lactone ring cleavage and decarboxylation of ellagic acid to form a pentahydroxy intermediate known as urolithin M5, followed by successive dehydroxylations. Specifically, dehydroxylation at the 3′ and 4′ positions converts urolithin M5 to urolithin C, and further dehydroxylation at the 9′ position yields urolithin A.
Key gut bacterial species involved in these transformations have been identified. Urolithin A was produced from ellagic acid, punicalagin, and an ellagitannin-rich walnut extract by fecal microbiota from human volunteers, demonstrating for the first time the production of urolithins by human gut microbiota. Specific genera including Gordonibacter and Ellagibacter have been implicated in different steps of the metabolic cascade, and recent research has identified molybdenum-dependent dehydroxylase enzymes as the catalytic machinery responsible for key transformation steps.
Unlike its precursors, which are not directly absorbed, urolithin A is produced in the colon and can be systemically absorbed, though its bioavailability varies significantly among individuals due to differences in gut microbial composition. After absorption, urolithin A enters the bloodstream via enterohepatic circulation, primarily existing as its phase II metabolites, urolithin A-glucuronides and urolithin A-sulfates. Upon reaching tissues, it dissociates into urolithin A monomers by enzymes and exerts its biological activity.
One of the most clinically significant aspects of urolithin A biology is the profound inter-individual variation in its endogenous production. The metabolic breakdown of ellagitannins and ellagic acid into urolithins depends on the person's gut microbiota composition. Individuals metabolizing ETs and EA into urolithins are categorized into three groups or phenotypes called metabotypes. Three human urolithin metabotypes have been previously described: metabotype 0 (urolithin non-producers), metabotype A (production of urolithin A as the unique final urolithin), and metabotype B (urolithin B and/or isourolithin A are produced alongside urolithin A).
Urolithin production capacity and, consequently, at least partly, the health effects associated with ellagitannin consumption vary among individuals because not everyone has the gut bacteria needed to produce all urolithins. Three urolithin metabotypes associated with three different production profiles have been described in both western and eastern populations. A large inter-individual variability has been observed in ex vivo experiments, suggesting that differences in microbiota composition affect urolithin production and therefore the potential health effects after consumption of ellagitannin-rich foods. Research has indicated that approximately 40% of adults are efficient converters, while the remaining population produces negligible urolithin A from dietary sources regardless of intake.
There has been substantial advance in the research on microorganisms involved in urolithin production, along with the compositional and functional characterization of the gut microbiota associated with urolithins metabolism that gives rise to the so-called urolithin metabotypes (UM-A, UM-B, and UM-0), relevant in human health.
Urolithin A as a defined chemical entity was not known to traditional medical cultures; its scientific isolation and characterization as a discrete gut metabolite occurred in the late twentieth century. Urolithins were first discovered as bioavailable metabolites from pomegranate ellagitannins approximately 20 years ago in animal models and in humans. About 20 years ago, urolithins were discovered as bioavailable metabolites produced by the human gut microbiota from ellagitannins and ellagic acid.
Nevertheless, the dietary precursor foods — particularly pomegranate (Punica granatum) — have extremely ancient histories of medicinal and nutritional use across multiple civilizations. Pomegranate is documented in Ayurvedic medicine, traditional Chinese medicine, and ancient Egyptian, Greek, and Roman medical traditions, where it was used for a wide range of purposes including digestive complaints, inflammation, and general vitality. The health benefits attributed to pomegranate have long been associated with its high content in polyphenols, particularly ellagitannins. It is now understood that many of the systemic, non-gastrointestinal effects historically ascribed to these whole foods were plausibly mediated, at least in part, by gut-derived urolithin metabolites that could be absorbed into circulation — a mechanism entirely unknown to premodern practitioners.
Over the past decade, research on urolithins has expanded significantly due to their role as mediators between polyphenol-rich diets and human health. The scientific recognition of urolithins as a distinct and pharmacologically relevant class of postbiotics is a development of the twenty-first century, with the body of clinical evidence accumulating primarily after 2015.
Urolithin A is commercially available in several supplemental forms. The most clinically studied proprietary preparation is a highly pure, synthetic urolithin A known by the trade name Mitopure, developed by Amazentis (now Timeline Nutrition), which has been used in multiple randomized controlled trials. This form delivers urolithin A directly, bypassing the gut microbiota conversion step entirely.
Considering the strict microbiome conditions necessary for urolithin A production from dietary sources, the most efficient approach to harness the biological effects of urolithin A is through in vitro synthesis followed by supplementation. Supplemental urolithin A is available in the following forms:
The U.S. Food and Drug Administration has given urolithin A a favorable review in its Generally Recognized as Safe (GRAS) notification program, with 1,000 mg per serving acknowledged in that review.
Urolithin A is described as a first-in-class natural compound that induces mitophagy both in vitro and in vivo following oral consumption. The primary action of urolithin A centers around its ability to induce mitophagy and autophagy, with research suggesting it is more potent in inducing mitophagy than general autophagy. Mitophagy is a process by which damaged mitochondria are selectively degraded and recycled to maintain mitochondrial quality.
Researchers have identified urolithin A as a potent activator of the phosphatase and tensin homolog (PTEN)-induced kinase-1 (PINK1)/parkin-dependent mitophagy pathway, which leads to the selective ubiquitination of mitochondrial proteins for phagolysosomal clearance. Urolithin A activates the PTEN induced kinase 1 (PINK1)/Parkin RBR E3 ubiquitin protein ligase (PRKN) pathway, which tags dysfunctional mitochondria for degradation, while also stimulating mitochondrial biogenesis via the sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) signalling axis.
More recently identified mechanisms reveal a broader inter-organellar role for urolithin A. Urolithin A-induced mitophagy restores age-associated organellar defects and reorganizes ER-mitochondria-lysosome communication through calcium signaling; urolithin A supplementation elevates intracellular calcium levels in various cell types, promoting mitophagy both in nematodes and mammalian cells. Calcium chelation abolishes urolithin A-induced mitophagy, blocking its beneficial impact on muscle function and lifespan, underscoring the critical role of calcium signaling in urolithin A's geroprotective effects. Furthermore, urolithin A-induced calcium elevation activates mitochondrial biogenesis via UNC-43/CAMK2D and SKN-1/NFE2L2/Nrf2 pathways, which are both essential for healthspan and lifespan extension.
Urolithin A activates AMPK, inhibits mTOR (the physiological inhibitor of mitophagy), increases PGC-1α levels and thus improves mitochondrial biogenesis. It also activates sirtuins and FOXO, with downstream antioxidant and anti-inflammatory effects. These combined effects result in improved mitochondrial function, increased ATP production, and enhanced muscle endurance, making urolithin A particularly effective in combating age-related mitochondrial dysfunction.
Urolithin A reduces inflammation by inhibiting NF-κB, suppressing pro-inflammatory cytokines, and activating Nrf2 in several animal models. It has the ability to modulate oxidative stress, either by enhancing endogenous antioxidant defenses or by inhibiting the production of reactive oxygen species (ROS).
Urolithin A and urolithin B exhibit AHR antagonist activity in a species-specific manner, inhibiting human (but not mouse) AHR. Urolithin A is a direct ligand for the AHR, as determined using ligand binding competition assays, and it exerts anti-inflammatory effects through this AHR-dependent mechanism. This represents a distinct mechanism that may contribute to urolithin A's immunomodulatory properties at the gut-immune interface.
This is the area with the strongest and most consistently replicated human clinical evidence for urolithin A.
Preclinical evidence: At the physiological level, urolithin A improved muscle function in nematodes, young rodents, old mice, and in muscle-wasting disorders such as Duchenne muscular dystrophy (DMD). The natural postbiotic urolithin A has been shown to promote mitophagy, mitochondrial function, and improved muscle function across species in different experimental models and across multiple clinical studies.
Phase I human clinical trial (Andreux et al., 2019 — Nature Metabolism): Andreux et al. pioneered the first double-blind, placebo-controlled randomized Phase I clinical trial to evaluate the safety and pharmacokinetic characteristics of urolithin A in elderly subjects (ClinicalTrials.gov: NCT02655393). The study enrolled healthy elderly male and female subjects aged 61 to 85 years. In this trial, researchers administered acute single doses (250, 500, 1,000, and 2,000 mg/day) and chronic doses of oral urolithin A for 4 weeks (250, 500, and 1,000 mg/day, 7 days/week) to healthy, sedentary elderly individuals, assessing both safety and bioavailability. Urolithin A was bioavailable in plasma at all doses tested, and 4 weeks of treatment at doses of 500 mg and 1,000 mg modulated plasma acylcarnitines and skeletal muscle mitochondrial gene expression in elderly individuals. These observed effects on mitochondrial biomarkers show that urolithin A induces a molecular signature of improved mitochondrial and cellular health following regular oral consumption in humans.
JAMA Network Open RCT (Older Adults, 2022): This double-blind, placebo-controlled randomized clinical trial enrolled adults aged 65 to 90 years and was conducted at a medical center and a cancer research center in Seattle, Washington, from 2018 to 2020. Muscle fatigue tests and plasma analysis of biomarkers were assessed at baseline, 2 months, and 4 months. Six-minute walk distance and maximal ATP production were assessed using magnetic resonance spectroscopy at baseline and end of study. Participants were randomized to receive daily oral supplementation with either 1,000 mg urolithin A or placebo for 4 months. The trial found that urolithin A supplementation was safe and well tolerated in the assessed population. Although the improvements in the 6-minute walk distance and maximal ATP production in the hand muscle were not statistically significant compared to placebo, long-term urolithin A supplementation was beneficial for muscle endurance and plasma biomarkers, suggesting that urolithin A may counteract age-associated muscle decline; however, future work is needed to confirm this finding.
Cell Metabolism RCT (Middle-Aged Adults, 2022): A randomized, placebo-controlled trial in middle-aged adults administered urolithin A (Mitopure), a known mitophagy activator, at two doses for 4 months (NCT03464500). The data showed significant improvements in muscle strength (approximately 12%) with intake of urolithin A. Clinically meaningful improvements were also observed in aerobic endurance (peak oxygen consumption, VO₂) and physical performance (6-minute walk test), but no significant improvement was found in peak power output (primary endpoint). Urolithin A significantly improved hamstring leg muscle strength at both doses (p = 0.027 for 500 mg; p = 0.029 for 1,000 mg compared with placebo). Hand-grip strength showed a 5.1% improvement from baseline in the 1,000 mg urolithin A dose group (p = 0.08). Levels of plasma acylcarnitines and C-reactive protein were significantly lower with urolithin A, indicating higher mitochondrial efficiency and reduced inflammation. Expression of proteins linked to mitophagy and mitochondrial metabolism in skeletal muscle was significantly increased with urolithin A administration.
Systematic review (2024): In five studies including 250 healthy individuals, urolithin A (10–1,000 mg/day) for a duration ranging from 28 days to 4 months showed a dose-dependent anti-inflammatory effect and upregulated some mitochondrial genes, markers of autophagy, and fatty acid oxidation. It did not affect mitochondrial maximal adenosine triphosphate production, biogenesis, dynamics, or gut microbiota composition. Urolithin A increased muscle strength and endurance; however, it had no significant effect on anthropometrics, cardiovascular outcomes, or physical function.
2025 systematic review on muscle outcomes: Study populations ranged in mean age from 24 to 72 years, with diverse groups including young strength-training athletes, middle-aged overweight or obese individuals, and older people. No study specifically targeted older people with sarcopenia. Intervention duration ranged from 8 weeks to 4 months, with a dose of 1 g/day used in all studies, while one trial also included a 500 mg/day arm. Adherence to study medication was reported as high for all three studies, and dropout rates were low (less than 10%) in all studies, with no excess of adverse events reported for participants taking urolithin A in any of the included studies.
Overall assessment: The clinical evidence for muscle endurance and strength benefits is among the most robust for any application of urolithin A, with multiple replicated RCTs. However, important limitations include the relatively small sample sizes, short intervention durations (maximum 4 months), and the fact that primary endpoints were not always met. No large-scale trials in clinically diagnosed sarcopenic populations have yet been conducted.
Growing scientific evidence points to mitochondrial dysfunction as a key contributor in the aging process and subsequent development of age-related pathologies. Under normal physiologic conditions, the body removes dysfunctional mitochondria via an autophagic process known as mitophagy. As mitophagy efficiency declines with age, damaged mitochondria accumulate, leading to oxidative stress, inflammation, and tissue dysfunction. This impairment is strongly linked to the progression of age-related diseases, highlighting the critical role of maintaining mitochondrial quality in healthspan and longevity.
The landmark 2016 paper by Ryu et al. in Nature Medicine demonstrated that urolithin A induces mitophagy and prolongs lifespan in C. elegans and increases muscle function in rodents — establishing the foundational preclinical rationale for human investigation. In human studies, mitochondrial gene expression signatures consistent with improved mitochondrial quality have been consistently observed in skeletal muscle biopsies following urolithin A supplementation, representing a validated biomarker endpoint.
In mammalian cells, urolithin A increases intracellular calcium, enhances mitophagy and mitochondrial metabolism, and mitigates stress-induced senescence in a calcium-dependent manner. These findings uncover a conserved mechanism by which urolithin A-induced mitophagy restores inter-organellar communication, supporting cellular homeostasis and organismal health.
Evidence strength: Preclinical evidence across multiple model organisms is strong and mechanistically well-characterized. Human evidence demonstrating mitochondrial gene expression changes is compelling. Clinical translation of these biomarker improvements into consistently measurable functional outcomes remains an active area of investigation.
Administration of urolithin A has been assessed mainly in Alzheimer's disease (AD) and ischemic neuronal injury models, resulting in improved cognition, reduced neuroinflammation, neuronal loss, tau phosphorylation, and amyloid plaques. In Parkinson's disease models, urolithin A has demonstrated multi-target neuroprotective effects. In a rotenone-induced rat model, urolithin A was detected in the brain following pomegranate juice intake, correlating with restored dopamine release and reduced α-synuclein levels. In mice treated with 6-hydroxydopamine, urolithin A enhanced mitochondrial biogenesis via the SIRT1/PGC-1α signaling pathway, increasing dopaminergic neuron survival in the substantia nigra and alleviating motor deficits.
The mechanisms by which urolithin A mitigates brain aging include promoting mitophagy, enhancing mitochondrial function, and reducing neuroinflammation. Neuroprotective properties in neurodegenerative disorders in preclinical models include improvement in cognition, motor activity, reduction of amyloid plaques, tau phosphorylation, neuronal loss, and neuroinflammation.
Preclinical evidence demonstrates urolithin A's therapeutic potential in CNS disorders such as Alzheimer's disease, Parkinson's disease, and stroke. Recent clinical trials involving urolithin A are presented in the literature, followed by analysis of the challenges associated with translating urolithin A-based interventions into clinical practice for CNS disorders.
Evidence strength: Predominantly preclinical (animal models and cell culture). Dedicated human RCTs specifically targeting neurodegenerative disease endpoints with urolithin A as the primary intervention had not been published at the time of this writing. The neurological evidence is promising but requires validation in human clinical trials before conclusions about therapeutic efficacy can be drawn.
Urolithin A exerts strong immunomodulatory effects, attenuating the production of pro-inflammatory cytokines such as IL-6, TNF-α, and IL-1β across multiple tissue types, including the brain, liver, adipose tissue, and gut. In the clinical study in middle-aged adults, levels of plasma acylcarnitines and C-reactive protein were significantly lower with urolithin A administration, indicating higher mitochondrial efficiency and reduced inflammation.
Urolithin A, the urolithin whose bioactivity has been most extensively studied, inhibits pro-inflammatory cytokine production and restores mitophagy in aged cells. Urolithin A exerts anti-inflammatory effects that occur through the aryl hydrocarbon receptor (AHR) in a species-specific manner.
Evidence strength: Anti-inflammatory biomarker reductions (CRP, acylcarnitines, specific cytokines) have been confirmed in human clinical trials. Direct clinical endpoints (i.e., reduction in inflammatory disease burden) have not been the primary focus of RCTs and require further investigation.
Many studies describe beneficial effects of urolithin A in aging, muscle dysfunction, inflammatory bowel disease (IBD), the nervous system, cardiovascular diseases, metabolic dysfunctions, and cancer. In rodent models of colitis, urolithin A has been shown to reduce inflammatory markers and exert protective effects on intestinal epithelial integrity. In vivo studies on animal models explore the potential favorable effects of urolithin A on aging, muscle dysfunctions, cardiovascular disease, inflammatory bowel diseases (IBD), cancer, metabolic disorders, and brain health.
Evidence strength: Primarily preclinical (rodent models and in vitro studies). Human clinical evidence for urolithin A specifically in IBD or other gastrointestinal conditions is lacking at this time.
Health benefits of urolithin A were also seen in age-associated cardiac disorders in preclinical models. The research provides evidence of anti-inflammatory, antiapoptotic, and antioxidant properties, as well as cardioprotective and neuroprotective effects of the metabolite in experimental settings. Urolithin A has been shown in animal studies to attenuate atherosclerotic plaque development and reduce markers of cardiac inflammation, plausibly via its NF-κB inhibitory and mitophagy-inducing properties.
Evidence strength: Predominantly preclinical. No dedicated human RCTs on cardiovascular outcomes have been completed. Indirect biomarker evidence from muscle/aging trials (reduced CRP) is suggestive but not sufficient to draw conclusions about cardiovascular benefit.
Urolithins are secondary polyphenol metabolites derived from gut microbial action on ellagitannins and ellagic acid-rich foods. They are emerging as a new class of anticancer compounds that can mediate their cancer-preventive activities through cell cycle arrest, aromatase inhibition, induction of apoptosis, tumor suppression, promotion of autophagy, and senescence, as well as transcriptional regulation of oncogenes and growth factor receptors.
Urolithin A decreases proliferation in ECC-1, Ishikawa, and HEC-1A human endometrial cancer cell lines at a concentration of 1 µM, arrests the cell cycle at the G2/M transition, and modulates estrogen receptor-regulated gene expression. It also potentiates the antiproliferative effect of 5-fluorouracil in Caco-2, SW480, and HT-29 cells. Urolithin A is a major metabolite found in malignant colonic tissues from colorectal cancer patients consuming pomegranate extract.
Evidence strength: Entirely preclinical and in vitro. There are no completed human interventional trials examining urolithin A's effects on cancer incidence, progression, or treatment response. The in vitro anticancer findings, while mechanistically interesting, cannot be extrapolated to clinical efficacy.
Urolithin A demonstrates osteoprotective effects through dual regulation of bone remodeling and delays joint degeneration by reducing synovial inflammation in preclinical models. Preclinical evidence in rodent models of osteoarthritis suggests that urolithin A reduces joint inflammation through its NF-κB and cytokine-suppressive effects. Preclinical health benefits of urolithin A were seen in osteoarthritis models.
Evidence strength: Preclinical only. Human clinical data in this area is absent.
Urolithin A and its metabolites (urolithin A-glucuronide and urolithin A-sulfate) were detected in plasma after both single doses (ranging from 250 to 2,000 mg) and after the last administration of 250–1,000 mg urolithin A daily for 28 days. Urolithin A was also detected in skeletal muscle after a single dose of 2,000 mg. The maximum plasma concentrations (Cmax) and total exposure (AUC) exhibited a dose-dependent increase. The time to maximal plasma concentration (Tmax) of urolithin A and its metabolites was 6 hours.
The half-life (t₁/₂) of urolithin A and its conjugates urolithin A-glucuronide and urolithin A-sulfate in plasma was 17–22 hours and 25–58 hours, respectively. The concentrations of both urolithin A and its metabolites reached a plateau after 7 days, maintaining consistency until 24 hours post-intervention. They were subsequently eliminated from plasma within 72–96 hours following the final administration of 250–1,000 mg urolithin A daily over a 28-day period.
Urolithin A at all tested doses showed good bioavailability in plasma, was unaffected by food intake, and did not accumulate. Urolithins circulate in plasma as glucuronide and sulfate conjugates at concentrations in the range of 0.2–20 µM under dietary exposure conditions.
The following dosages have been specifically reported in clinical research:
No clinical studies at the time of this writing have specifically established a minimum effective dose or an upper tolerable limit in humans beyond the GRAS assessment framework. In systematic review of muscle outcome studies, a dose of 1 g/day was used in all included studies.
The aim of the first safety study was to investigate the genotoxicity, toxicokinetics, and repeated-dose safety of orally administered synthetic urolithin A in rats. The battery of genotoxicity assays demonstrated that urolithin A is not genotoxic. The 28-day and 90-day repeated-dose studies showed no alterations in clinical parameters or blood markers at any tested dose level.
Oral urolithin A demonstrated excellent safety in both single-dose escalation (250–2,000 mg) and multiple-dose escalation (250–1,000 mg daily for 28 days) cohorts. Urolithin A at all tested doses showed good bioavailability in plasma, was unaffected by food intake, and did not accumulate. Findings from the randomized clinical trial in older adults indicated that urolithin A was safe and well tolerated as well as beneficial for muscle endurance and mitochondrial health in older adults. Dropout rates were low (less than 10%) in all included studies, with no excess of adverse events reported for participants taking urolithin A in any of the included studies.
The U.S. Food and Drug Administration has given urolithin A a favorable review in its GRAS (Generally Recognized as Safe) notification program, at 1,000 mg per serving. This regulatory review, designated as GRAS Notice No. GRN 000791, represents formal U.S. regulatory acknowledgment of the compound's safety at the studied dose level for use in conventional foods.
ADME studies showed that glucuronidated and sulfonated forms of urolithin A are the predominant metabolites following both oral and intravenous administration. The compound's rapid and complete conversion to conjugated forms, combined with its observed non-accumulation in clinical studies, is considered a favorable safety feature. Urolithin A prevents the accumulation of damaged or dysfunctional mitochondria and has a favorable safety rating according to standardized toxicology tests.
Several important gaps in the safety literature should be noted. Virtually all human clinical trials have been conducted in healthy adults; safety data in individuals with significant hepatic or renal impairment, pregnant or lactating individuals, or pediatric populations are not established in the published literature. The longest continuous human intervention in published trials is 4 months; long-term (multi-year) safety data in humans has not been reported. Additionally, the bioavailability and physiological effects of urolithin A depend on factors such as gastrointestinal pH, solubility, and the individual's gut microbiota composition, and it is not yet known whether these factors modulate safety outcomes.
Urolithin A modulates the expression of numerous genes related to phase I and phase II xenobiotic metabolism. This metabolic enzyme modulation raises the theoretical possibility of interactions with drugs that are substrates of these pathways, particularly CYP450 enzymes and phase II conjugation enzymes. However, direct human pharmacokinetic drug interaction studies for urolithin A had not been published in the peer-reviewed literature at the time of this writing. The design of in vitro studies using physiologically relevant assay conditions (molecular forms and concentrations) is still a pending subject, making some reported urolithin activities — including those relevant to drug interaction risk — questionable.
Despite promising in vivo results, the direct evidence of the health advantages and mechanisms of action of urolithin A are still open to dispute. Remarkable progress has been made in the research on the safety, bioactivity, and associated mechanisms of urolithin A, including the first human interventions; however, many in vitro results await confirmation in well-designed human trials.
Key limitations of the current evidence base include:
Health conditions that Urolithin a may help support.
UA activates the Nrf2/ARE antioxidant pathway, upregulating endogenous antioxidant enzymes and reducing reactive oxygen species. In human trials, plasma oxidative stress markers (acylcarnitines, CRP) are consistently reduced. UA's antioxidant and anti-inflammatory effects are documented across preclinical models and mechanistically confirmed in human studies.
Multiple preclinical and in vitro studies show UA reduces osteoarthritis pathology by improving mitochondrial health in chondrocytes, reducing cartilage degeneration, and suppressing synovial inflammation. UA also attenuates rheumatoid arthritis symptoms in CIA mouse models by inhibiting NF-κB-driven inflammation and pyroptosis. No dedicated human arthritis RCTs have yet been completed.
Multiple randomized controlled trials show Urolithin A (UA) improves aerobic capacity, muscle strength, and exercise performance in middle-aged and older adults. A 2025 RCT in competitive distance runners further demonstrated increased VO2max and reduced perceived exertion. Mechanistically, UA activates mitophagy, improving mitochondrial quality control in skeletal muscle.
Preclinical and in vitro studies—including work with human chondrocytes from OA patients—show UA improves mitophagy and mitochondrial respiration in cartilage cells and reduces cartilage degeneration. UA promotes anabolic matrix factors and suppresses catabolic enzymes in chondrocytes. Human clinical data on cartilage-specific outcomes are not yet available.
UA's primary mechanism of action is mitophagy induction—clearing dysfunctional mitochondria and promoting mitochondrial biogenesis, thereby directly improving cellular ATP production capacity. Human RCT evidence shows UA increases mitochondrial gene expression in skeletal muscle and improves biomarkers of mitochondrial efficiency.
Human RCTs consistently show that UA supplementation reduces circulating inflammatory markers including CRP and plasma acylcarnitines. UA inhibits NF-κB signaling and suppresses pro-inflammatory cytokines in preclinical models. Clinical researchers describe it as targeting 'inflammaging'—the low-grade chronic inflammation associated with aging.
UA is increasingly studied for cognitive aging due to its BBB permeability, mitophagy-activating mechanism in neurons, and anti-neuroinflammatory effects. Preclinical studies show benefits in Alzheimer's and aging-related cognitive models. Human data from adjacent trials show systemic healthy-aging biomarker improvements; dedicated cognitive aging RCTs are underway.
UA is itself a product of gut microbial metabolism of ellagitannins and its production varies greatly by individual microbiome composition. In gut models, UA strengthens intestinal barrier function by upregulating epithelial tight junction proteins via aryl hydrocarbon receptor (AhR)-Nrf2 pathways. Only approximately one-third of people have the microbiota capable of efficiently converting ellagitannins to UA.
UA sits at the intersection of gut microbial metabolism and CNS health. It is produced by gut bacteria, crosses the blood-brain barrier, and its pleiotropic activities—including anti-inflammatory and mitophagy-inducing effects—are mechanistically relevant to the gut-brain axis. Preclinical data link gut-derived UA to neuroprotective outcomes via the gut-brain axis.
Urolithin A is a gut microbial metabolite produced from ellagitannins (from pomegranate, walnuts, berries) that potently induces mitophagy, clearing damaged mitochondria in aging cells. Multiple clinical trials demonstrate urolithin A supplementation improves muscle endurance, mitochondrial health biomarkers, and muscle strength in middle-aged to older adults.
UA has demonstrated cardioprotective effects in preclinical models including diabetic cardiomyopathy and heart failure, and a human RCT found that 1 g/day UA for 4 months reduced plasma ceramide levels—a cardiovascular biomarker. A small pilot RCT in heart failure with reduced ejection fraction found no significant echocardiographic improvements, though the trial was likely underpowered.
Preclinical and mechanistic studies show UA reduces intestinal inflammation relevant to IBD by strengthening the epithelial barrier, inhibiting NF-κB in gut-resident immune cells, and upregulating tight junction proteins via AhR-Nrf2 pathways. Ellagitannin-rich foods have documented benefits in IBD, with UA as the proposed active metabolite. Dedicated human IBD RCTs are not yet published.
Preclinical studies show UA crosses the blood-brain barrier and exerts neuroprotective effects relevant to memory, reducing amyloid pathology and neuroinflammation in animal models. Clinical evidence directly linking UA to memory improvement in humans is still lacking, but emerging data on its effects in the CNS warrant inclusion as scientific based on mechanistic human data.
Urolithin A is a gut microbiota-derived metabolite from polyphenols (ellagic acid/ellagitannins) that is one of the most potent known activators of mitophagy in humans. Clinical trials show it improves mitochondrial efficiency, muscle function, and exercise performance by enhancing the clearance of damaged mitochondria.
A 2025 RCT in competitive distance runners found UA supplementation significantly reduced indirect markers of muscle damage following exercise compared to placebo. Mechanistically, UA's mitophagy activation and anti-inflammatory effects (reduced CRP, acylcarnitines) support faster recovery of muscle function after exertion.
Clinical evidence from a 2025 RCT in trained runners demonstrates reduced perceived exertion and lower indirect muscle damage biomarkers following UA supplementation during intense training. Anti-inflammatory effects—including reduced CRP—seen across multiple human trials also support a role in reducing post-exercise soreness.
UA's anti-inflammatory, antioxidant, and mitophagy-enhancing properties are mechanistically highly relevant to Parkinson's disease (PD). Preclinical studies show UA preserves dopaminergic neurons, inhibits α-synuclein aggregation, and suppresses neuroinflammation. The Buck Institute is conducting dedicated UA PD research; however, PD-specific human trial data are limited to early-phase work.
Multiple human RCTs show UA improves muscle endurance and aerobic capacity. The Liu et al. (JAMA Network Open, 2022) trial in older adults found significant improvements in leg and hand muscle endurance with 1000 mg/day UA over 4 months. The Singh et al. (2022) trial in middle-aged adults showed clinically meaningful gains in VO2peak and 6-minute walk test performance.
Three separate randomized clinical trials of topical UA evaluated its effect on skin aging. In an 8-week RCT (n=108), topical 1% UA cream significantly reduced wrinkle volume and depth, with subjects reporting visible improvement in fine lines within 2 weeks. Skin biopsies confirmed significant upregulation of collagen organization and assembly genes.
A randomized placebo-controlled clinical trial found topical 1% UA cream significantly reduced UV-induced erythema by approximately 14% compared to an untreated skin area. Lower-dose UA and placebo showed no protective benefit. Mechanistically, UA reduces skin inflammatory signaling and supports immune cells in the skin against UV-driven damage.
Body systems that Urolithin a may help support.
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