Urolithin A (often abbreviated as UA) is a small molecule produced when certain gut bacteria break down ellagic acid, a polyphenol found in foods such as pomegranates, berries, nuts and some grains. Unlike the parent compound, which is poorly absorbed, urolithin A can cross the intestinal barrier and reach tissues throughout the body, where it exerts biological effects that have attracted scientific interest.
Research over the past decade has moved urolithin A from a curiosity of food chemistry to a candidate for supporting cellular health. Studies in animals, cell cultures and, more recently, healthy volunteers have shown that UA can stimulate a process called mitophagy, the selective removal of damaged mitochondria, and improve several markers of metabolic and organ function. This article summarizes what urolithin A is, how it is made in the gut, the key mechanisms that have been documented, and what current human evidence tells us.
Key Takeaways
- Urolithin A is a gut‑derived metabolite of ellagic‑rich foods that can be absorbed and reach peripheral tissues.
- Its proposed cellular action is to stimulate mitophagy, a finding mostly from cells, worms and mice [13][14][15], helping cells replace damaged mitochondria with healthier ones.
- Small human trials report that UA was well tolerated and shifted some mitochondrial biomarkers; strength and endurance results were secondary findings in company-funded trials [2][11][12], but long‑term outcomes are still unknown.
- Advanced delivery forms (liposomes, gum‑arabic nanoparticles) increase UA stability and absorption in experimental settings.
- Pre‑clinical studies suggest organ‑specific protective effects (brain, liver, pancreas, heart), yet clinical confirmation is pending.
How Urolithin A Is Formed in the Body
Ellagic acid is a polyphenol that is abundant in pomegranate juice, strawberries, raspberries, walnuts and some oak‑derived foods. When these foods are eaten, ellagic acid reaches the colon largely unchanged because it is not well digested by human enzymes. Specific strains of gut bacteria, such as Gordonibacter spp., possess enzymes that convert ellagic acid into a series of metabolites called urolithins; the most studied of these is urolithin A [1].
In human trials, 25 to 80% of volunteers made only urolithin A and 5 to 25% made none
25 to 80% of volunteers
Produced only urolithin A conjugates, across the different ellagitannin trials.
Seen more in chronic illness
A higher share was found in volunteers with metabolic syndrome or colorectal cancer, conditions linked to gut microbial imbalance.
5 to 25% of volunteers
No urolithins were detected.
Whether you make urolithin A from food varies a lot between people, so food intake alone does not predict it.
Ranges are pooled across several human trials, mostly European. The three types appeared regardless of age, gender, BMI or food source. Source: Tomas-Barberan et al., Journal of Agricultural and Food Chemistry 2014; Hu et al., Frontiers in Nutrition 2026.
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The conversion depends on an individual’s microbial composition. Some people are “high producers” and generate measurable levels of UA in the bloodstream after a meal, while others produce little or none. The metabolite is then absorbed through the colon, travels via the portal vein to the liver, and is distributed to peripheral tissues where it can engage cellular pathways.
The Core Biological Action: Activating Mitophagy
Mitochondria are the power plants of the cell, but they accumulate damage with age or stress. Mitophagy is a quality‑control system that tags dysfunctional mitochondria for removal, allowing healthier organelles to take their place. Urolithin A is proposed to stimulate this pathway, in which the PINK1 protein recruits PARKIN to damaged mitochondria so they are removed [13][2].
Research note: Enterocloster species carry the dehydroxylases that decide which urolithin end products are made, Gordonibacter handles early steps and Ellagibacter relates to isourolithin A [16].
In a first-in-human trial in healthy, sedentary elderly adults, four weeks of daily supplementation with UA at 500 mg and 1,000 mg modulated plasma acylcarnitines and skeletal muscle mitochondrial gene expression, with a favorable safety profile [2]. These findings were secondary outcomes, so they are biomarker signals rather than proof of better muscle function [2], a process that underlies many aspects of cellular vitality.
Beyond Mitochondria: Other Cellular Pathways Influenced by UA
While mitophagy is the most frequently highlighted mechanism, UA also interacts with other protective pathways. In mouse models, UA activates the Nrf2 antioxidant response, strengthening the gut barrier and reducing inflammation [3]. Liposomal formulations that improve UA stability have shown even greater bioavailability, further enhancing these effects in pre‑clinical studies [4].
Additionally, UA modulates lysosomal function, helping cells clear protein aggregates and damaged cellular components. This lysosomal rejuvenation was linked to cognitive benefits in a mouse model of Alzheimer’s disease, where UA treatment restored memory performance and reduced amyloid pathology [5].
Human Evidence: Safety, Bioavailability, and Early Health Signals
A systematic review of clinical investigations concluded that short‑term UA supplementation (up to 4 months) was reported as well tolerated, with adverse events judged mild or moderate and unrelated, in studies of healthy adults and older volunteers [11][6]. The same review of five studies in 250 healthy people found a dose-dependent anti-inflammatory effect and some upregulated mitochondrial genes, but no effect on maximal mitochondrial ATP production, and no effect on physical function, anthropometrics or cardiovascular outcomes. It called for further research over longer periods [6].
Bioavailability studies indicate that UA reaches peak plasma concentrations within a few [2] hours after oral intake, and that encapsulation technologies such as pH‑driven liposomes or gum‑arabic coated nanoparticles can further increase systemic exposure [4][7]. These delivery advances are important because the native compound is relatively unstable in the acidic stomach environment.
Two company-funded trials missed their primary endpoints: peak power output in 88 middle-aged adults and six-minute walk distance in 66 older adults. Strength and endurance gains were secondary results [11][12].
Potential Organ‑Specific Benefits Observed in Pre‑clinical Models
Several animal studies have explored how UA may protect specific organs. In a model of pancreatic injury, UA reduced inflammation and fibrosis, suggesting a protective role in pancreatic disease [8]. In chronic alcohol‑related liver disease, UA acted through the gut‑microbiota‑liver axis, improving liver histology and decreasing markers of oxidative stress, an effect that required the presence of the hepatokine MUP1 [9].
Cardiovascular toxicity from chemotherapy (cisplatin) was mitigated in mice by UA‑loaded nanoparticles, which dampened inflammation‑driven lymphangiogenesis and preserved cardiac function [10]. Although these findings are encouraging, they remain pre‑clinical and cannot be directly extrapolated to human disease.
Where to Find Urolithin A
- Double Wood Urolithin A (generic, budget-friendly)
- Mitopure by Timeline (the clinically studied branded form)
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A Note on the Evidence
Current evidence is limited to short‑term studies in healthy or at‑risk volunteers; UA should not replace medical treatment, and people with liver disease, pregnancy, or on medication should consult a healthcare professional before using supplements.
Frequently Asked Questions
How is urolithin A different from ellagic acid?
Ellagic acid is the plant‑derived precursor that is poorly absorbed; gut bacteria convert it into urolithin A, which is much more bioavailable and able to act on cellular pathways such as mitophagy [1].
Can I get enough urolithin A from diet alone?
Dietary intake of ellagic‑rich foods can produce UA in people who harbor the right gut microbes, but circulating levels vary widely. Supplementation provides a standardized dose and ensures exposure regardless of individual microbiota composition [1].
Is urolithin A safe to take?
Short‑term clinical studies (up to 4 months) have reported mostly mild adverse events judged unrelated to treatment in healthy adults [11][6][2]. Long‑term safety has not been fully established.
Does urolithin A improve memory or treat Alzheimer’s disease?
In mouse models of Alzheimer’s, UA restored cognition and enhanced mitophagy and lysosomal function [5]. Human data are limited to biomarker studies; UA is not a proven treatment for dementia.
Who might benefit most from urolithin A supplementation?
Older adults or individuals with reduced mitochondrial efficiency have been studied in small trials funded by the maker of Mitopure, where primary endpoints were missed and muscle endurance and some biomarkers improved as secondary results [11][12][2][6].
Do I need a special formulation to get the benefits?
Standard capsules deliver measurable UA, but formulations that protect UA from stomach acid, such as pH‑responsive liposomes or gum‑arabic coated nanoparticles, have shown higher bioavailability in experimental studies [4][7].
References
- Zhang M et al. Ellagic acid and intestinal microflora metabolite urolithin A: A review on its sources, metabolic distribution, health benefits, and biotransformation. Critical reviews in food science and nutrition (2023). PMID 35142569
- Andreux PA et al. The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humans. Nature metabolism (2019). PMID 32694802
- Singh R et al. Enhancement of the gut barrier integrity by a microbial metabolite through the Nrf2 pathway. Nature communications (2019). PMID 30626868
- Hu Y et al. Liposomes encapsulation by pH driven improves the stability, bioaccessibility and bioavailability of urolithin A: A comparative study. International journal of biological macromolecules (2023). PMID 37865359
- Hou Y et al. Urolithin A improves Alzheimer's disease cognition and restores mitophagy and lysosomal functions. Alzheimer's & dementia : the journal of the Alzheimer's Association (2024). PMID 38753870
- Kuerec AH et al. Targeting aging with urolithin A in humans: A systematic review. Ageing research reviews (2024). PMID 39002645
- Zhang L et al. Gum arabic-coated urolithin A liposome nanoparticles: Fabrication, characterization, bioavailability and improved alleviation on NAFLD activity in vivo. Carbohydrate polymers (2026). PMID 42097775
- Li K et al. Ameliorative Effects of Gut Microbial Metabolite Urolithin A on Pancreatic Diseases. Nutrients (2022). PMID 35745279
- Zhang H et al. MUP1 mediates urolithin A alleviation of chronic alcohol-related liver disease via gut-microbiota-liver axis. Gut microbes (2024). PMID 38889450
- Wahab AT et al. Urolithin A-laden functional nanoparticles alleviate cisplatin-induced cardiotoxicity in mice by inhibiting inflammation-induced lymphangiogenesis. Free radical biology & medicine (2025). PMID 40516794
- Singh A et al. Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomized trial in middle-aged adults. Cell reports. Medicine (2022). PMID 35584623
- Liu S et al. Effect of Urolithin A Supplementation on Muscle Endurance and Mitochondrial Health in Older Adults: A Randomized Clinical Trial. JAMA network open (2022). PMID 35050355
- Peter M. J. Quinn et al. PINK1/PARKIN signalling in neurodegeneration and neuroinflammation. Acta Neuropathologica Communications (2020). PMID 33168089
- Gao Z et al. Urolithin A protects against acetaminophen-induced liver injury in mice via sustained activation of Nrf2. International journal of biological sciences (2022). PMID 35342347
- Ryu D et al. Urolithin A induces mitophagy and prolongs lifespan in C. elegans and increases muscle function in rodents. Nature medicine (2016). PMID 27400265
- Lingmin Hu et al. Urolithins in clinical translation: from gut microbial metabolites to precision interventions. Frontiers in Nutrition (2026). PMID 42626640
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.