Urolithin A is a compound produced when gut bacteria metabolize ellagitannins — polyphenols found in pomegranates, walnuts, and certain berries. It has drawn scientific attention largely for its ability to activate mitophagy, a cellular housekeeping process that identifies and removes damaged mitochondria. The kidneys are among the most metabolically demanding organs in the body, filtering roughly 180 liters of blood per day, which makes mitochondrial health especially consequential for how well they function under stress or injury.
Research into urolithin A and kidney health is still predominantly preclinical, with the bulk of findings coming from rat and mouse models rather than human clinical trials. The picture that emerges is genuinely interesting but also nuanced: multiple animal studies point to protective mechanisms against several types of kidney injury, while a 2026 case report introduced the first documented human cases of urolithin A-associated kidney stones — a finding that deserves careful attention. This article summarizes what the current evidence shows, what remains unproven, and the caveats anyone should consider before supplementing.
Key Takeaways
- Multiple rat and mouse studies suggest urolithin A may protect kidney cells from ischemia-reperfusion injury, chemotherapy toxicity, and calcium oxalate stone formation through antioxidant, anti-inflammatory, and mitophagy-restoring mechanisms [PMID 35040204, PMID 28784820, PMID 41265017].
- Urolithin A activates mitophagy — the cellular process that removes dysfunctional mitochondria — which is especially relevant in the metabolically demanding kidney.
- A 2026 case report documented the first known human cases of urolithin A renal calculi, a safety signal that is particularly relevant for individuals with a personal or family history of kidney stones [7].
- Almost all kidney-specific evidence comes from animal models; human clinical data on kidney outcomes are currently lacking.
- Individual gut microbiome differences mean that dietary ellagitannin sources like pomegranate do not reliably produce consistent urolithin A levels across people [3].
How Urolithin A Acts on Kidney Cells
Urolithin A’s central mechanism of interest is mitophagy activation — the selective process by which cells tag dysfunctional mitochondria for degradation and recycling. When mitochondria are damaged, they generate excessive reactive oxygen species (free radicals), trigger inflammatory signaling, and can initiate apoptosis (programmed cell death). In kidney tissue, where mitochondrial density is high, this cascade can rapidly translate into measurable organ damage.
Preclinical research has identified several specific signaling pathways through which urolithin A appears to act in renal tissue. Studies have documented activity through the p62-Keap1-Nrf2 axis, a well-characterized regulator of antioxidant gene expression [2], and modulation of FOXO3, a transcription factor associated with oxidative stress resistance and cell survival [6]. A systematic review of in vivo urolithin research confirmed the compound’s broad anti-inflammatory and antioxidant properties across multiple organ systems, though it also emphasized that most evidence comes from animal models [3].
Ischemia-Reperfusion Kidney Injury
Ischemia-reperfusion injury (IRI) occurs when blood supply to the kidney is interrupted and then restored — a scenario encountered in kidney transplantation, major cardiovascular surgery, and critical illness. The restoration of blood flow paradoxically triggers a burst of oxidative stress and inflammation that can cause severe acute kidney injury.
A 2022 study in a rat IRI model found that urolithin A reduced markers of acute kidney injury, with the protective effect attributed to activation of the Nrf2 antioxidant pathway through p62-Keap1 signaling [2]. A 2025 study examining the same injury type found that urolithin A modulated FOXO3 gene expression in renal tissue, pointing to an additional mechanism by which the compound may help cells withstand oxidative damage [6]. Both studies are preclinical, and it is not yet established whether similar protective effects occur in humans.
Chemotherapy-Related Kidney Toxicity
Cisplatin is a commonly used chemotherapy agent that causes nephrotoxicity as a frequent and dose-limiting side effect. Researchers use cisplatin-treated rats as a standardized model for studying potential kidney-protective compounds.
A 2017 experimental study found that urolithin A reduced cisplatin-induced kidney damage in rats, with the effect linked to inhibition of renal inflammation and apoptosis [1]. Animals treated with urolithin A showed lower levels of kidney injury biomarkers and reduced inflammatory signaling compared to untreated controls. This is preliminary animal research. It does not support using urolithin A alongside chemotherapy without explicit medical guidance, and potential interactions with cancer treatment would need to be thoroughly studied in humans before any such recommendation could be made.
Kidney Stones: Both a Potential Protective Role and a New Risk Signal
The relationship between urolithin A and kidney stones is the most clinically complex aspect of this topic and includes a recent safety finding that warrants honest attention. On the protective side, a 2026 preclinical study found that urolithin A reduced calcium oxalate crystal deposition and associated kidney injury in a kidney stone disease model. The proposed mechanism involved regulation of PCK1 — a metabolic enzyme — to restore mitophagy function in renal tubule cells [5]. Calcium oxalate is the most common type of kidney stone in humans, and this finding suggests a potential protective role in that specific context.
However, a separate 2026 case report documented the first known human cases of urolithin A renal calculi — kidney stones apparently composed of or associated with urolithin A itself [7]. This is a small number of cases and does not establish that supplemental urolithin A causes kidney stones broadly. Nevertheless, it is a clinically meaningful signal, particularly for individuals with a history of kidney stones, impaired kidney function, or other metabolic risk factors. The animal data on calcium oxalate protection and the human case reports on urolithin A calculi are not necessarily contradictory — they may reflect different mechanisms — but the picture at the human level is not yet resolved.
Autoimmune Kidney Disease: Early Findings in Lupus Nephritis
Lupus nephritis is kidney inflammation caused by systemic lupus erythematosus, an autoimmune condition that can lead to progressive kidney damage and failure. A 2026 mouse model study examined whether urolithin A could complement existing immunosuppressive therapy in this context. The researchers found that combining cyclosporine A — a standard immunosuppressant — with urolithin A produced better outcomes in the lupus nephritis mouse model than either agent alone, suggesting that urolithin A may help modulate inflammatory and immune responses within the kidney [8].
This is early-stage animal research and should not be interpreted as a treatment recommendation for lupus nephritis or any autoimmune kidney condition. Lupus nephritis management is clinically complex, and any consideration of adjunct therapies must take place under close medical supervision.
Dietary Sources, Individual Variability, and Supplementation
Urolithin A is not consumed directly from food. It is produced when the gut microbiome breaks down ellagitannins — polyphenols concentrated in pomegranates, certain berries, and walnuts. Pomegranate in particular has been examined for its broader health effects: a 2025 review noted the therapeutic potential of pomegranate compounds in noncommunicable disease management, with urolithin A production cited as one of the proposed biological mechanisms [4].
A critical practical issue is that urolithin A production varies substantially between individuals depending on gut microbiome composition. Research has shown that some people convert ellagitannins efficiently while others produce little or no urolithin A from the same food intake [3]. This variability is one reason direct supplementation has been studied as a way to bypass gut-dependent conversion. However, the kidney stone case report noted above [7] is directly relevant to supplementation scenarios, where urolithin A concentrations may be higher and more consistent than those achieved through diet.
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A Note on the Evidence
The large majority of kidney-related urolithin A research has been conducted in animal models, and results may not translate to humans. A 2026 case report identified the first documented human cases of urolithin A renal calculi, so individuals with a personal or family history of kidney stones, existing kidney disease, or other relevant metabolic conditions should consult a physician before using urolithin A supplements. This article is for informational purposes only and does not constitute medical advice.
Frequently Asked Questions
Does urolithin A protect the kidneys?
Animal studies suggest urolithin A may help protect kidney cells from certain types of injury — including ischemia-reperfusion damage and cisplatin-induced toxicity — through antioxidant and anti-inflammatory mechanisms [PMID 35040204, PMID 28784820]. These findings have not yet been confirmed in human clinical trials specifically measuring kidney outcomes, so no protective claim can be made for humans at this time.
Can urolithin A cause kidney stones?
A 2026 case report described the first documented human cases of urolithin A renal calculi, indicating that urolithin A itself can form or contribute to kidney stones in some individuals [7]. This involves a small number of cases and does not establish a broad causal link, but it is a real safety signal. Anyone with a history of kidney stones or reduced kidney function should discuss this finding with their doctor before taking urolithin A supplements.
What cellular mechanism explains urolithin A's potential kidney benefits?
Urolithin A activates mitophagy — the process by which cells identify and degrade damaged mitochondria before they generate excess oxidative stress. In kidney injury models, researchers have also observed urolithin A acting through the p62-Keap1-Nrf2 antioxidant pathway and modulating FOXO3, a transcription factor linked to oxidative stress resistance [PMID 35040204, PMID 41620864]. Together, these actions may reduce cell death and inflammation in stressed kidney tissue.
Is there research on urolithin A and autoimmune kidney disease?
One 2026 mouse model study found that combining urolithin A with cyclosporine A improved outcomes in lupus nephritis compared to cyclosporine alone, suggesting urolithin A may complement immunosuppressive therapy in this autoimmune kidney condition [8]. This is very early animal research and does not support using urolithin A as a treatment for lupus nephritis or any other autoimmune kidney disease in humans.
Does eating pomegranates provide urolithin A for kidney health?
Pomegranates are a rich source of ellagitannins, which gut bacteria can convert into urolithin A. However, individual gut microbiome composition determines how much urolithin A a person actually produces, and research confirms wide variation between individuals — some produce meaningful amounts while others produce very little from the same diet [PMID 36079752, PMID 40726148]. Eating pomegranates does not guarantee clinically significant urolithin A exposure.
Can urolithin A help with calcium oxalate kidney stones?
A 2026 preclinical study found that urolithin A reduced calcium oxalate crystal deposition and kidney injury in an animal kidney stone model, with the proposed mechanism involving restoration of mitophagy through PCK1 regulation in renal tubule cells [5]. This is animal data only. Importantly, a separate 2026 case report documented human cases of urolithin A-associated renal calculi [7], so the overall picture regarding urolithin A and kidney stone risk in humans is not yet clear and warrants caution.
References
- Guada M et al. Urolithin A Mitigates Cisplatin-Induced Nephrotoxicity by Inhibiting Renal Inflammation and Apoptosis in an Experimental Rat Model. The Journal of pharmacology and experimental therapeutics (2017). PMID 28784820
- Zhang Y et al. Urolithin A alleviates acute kidney injury induced by renal ischemia reperfusion through the p62-Keap1-Nrf2 signaling pathway. Phytotherapy research : PTR (2022). PMID 35040204
- Tow WK et al. The Therapeutic Relevance of Urolithins, Intestinal Metabolites of Ellagitannin-Rich Food: A Systematic Review of In Vivo Studies. Nutrients (2022). PMID 36079752
- Rahman AU et al. The therapeutic potential of pomegranate in the prevention and management of noncommunicable diseases. Food & function (2025). PMID 40726148
- Sun X et al. Urolithin A protects against calcium oxalate-induced crystal formation and kidney injury by regulating PCK1 to restore mitophagy function in kidney stone disease. Biochimica et biophysica acta. Molecular basis of disease (2026). PMID 41265017
- Abosaooda M et al. Modulation of renal FOXO3 gene expression by Urolithin A in a rat model of renal ischemia-reperfusion injury. Wiadomosci lekarskie (Warsaw, Poland : 1960) (2025). PMID 41620864
- Best SL et al. First Reported Human Cases of Urolithin A Renal Calculi. Kidney international reports (2026). PMID 42058113
- Ganugula R et al. Combined cyclosporine A and urolithin A therapy ameliorates murine lupus nephritis. Journal of immunology (Baltimore, Md. : 1950) (2026). PMID 42130005
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.
