Reproductive cells are among the most mitochondria-dependent in the human body. Eggs, sperm, and early embryos rely heavily on mitochondrial energy production to mature, fertilize, and divide correctly. As mitochondrial function declines with age or under metabolic stress, gamete quality can suffer. Urolithin A, a compound produced by gut bacteria from polyphenols in pomegranates, berries, and walnuts, has attracted research interest in part because it activates mitophagy—the cellular process by which damaged mitochondria are cleared and replaced.
A small but growing body of animal and laboratory research is exploring whether urolithin A’s mitochondrial effects extend to reproductive biology. The findings, mostly from studies in rats, cattle, and pigs, are preliminary and have not yet been confirmed in human clinical trials. This article summarizes what the current evidence does and does not say, and flags clearly where the science is still early.
Key Takeaways
- Reproductive cells are highly mitochondria-dependent, which is the theoretical basis for asking whether urolithin A—a mitophagy activator—may affect fertility-related biology.
- Animal and laboratory studies suggest urolithin A may protect egg quality under oxidative stress conditions [1] and reduce sperm damage caused by diabetes in rats [2].
- A 2025 mouse study found urolithin A was associated with better preservation of ovarian follicles following chemotherapy, via a PI3K/Akt-related mechanism [3].
- No human clinical trials have tested urolithin A specifically for fertility outcomes; all current reproductive research is preclinical.
- Anyone with fertility concerns should consult a qualified medical professional rather than rely on supplements based on early animal research.
Why Mitochondria Matter for Fertility
Mitochondria generate ATP, the energy currency cells use to carry out virtually every function. In reproductive biology, this matters in specific and measurable ways. Oocytes (eggs) require enormous amounts of ATP to complete meiosis, resist oxidative damage during maturation, and support fertilization. Sperm depend on mitochondria to power motility and survive the journey to fertilization. Early embryos lack the ability to generate their own energy efficiently until a few days after fertilization, making them entirely dependent on maternally inherited mitochondria.
Mitophagy—the selective recycling of damaged or dysfunctional mitochondria—acts as a quality-control mechanism. When mitophagy is impaired, damaged mitochondria accumulate, reactive oxygen species (ROS) build up, and cells become increasingly prone to dysfunction or death. Urolithin A is one of the best-characterized natural activators of mitophagy. This is the theoretical basis for asking whether it might benefit reproductive cells under stress.
Urolithin A and Egg (Oocyte) Quality
Several animal studies have looked directly at whether urolithin A can protect oocyte quality. A 2021 study using bovine oocytes aged in vitro found that urolithin A treatment was associated with improvements in markers of mitochondrial function and reductions in oxidative stress indicators, suggesting a potential anti-aging effect on eggs in a laboratory setting [4]. While bovine oocytes are a standard model in reproductive biology, findings from cattle cannot be directly extrapolated to human fertility outcomes.
A 2025 study using porcine (pig) oocytes exposed to artificially induced oxidative stress found that urolithin A treatment was associated with better maturation rates and improved subsequent embryo development compared with untreated controls [1]. The researchers identified reductions in ROS accumulation and improvements in mitochondrial membrane potential as likely mechanisms. Again, this is a controlled laboratory model, not a clinical study in people.
These oocyte studies are consistent with urolithin A’s known mechanism—mitophagy activation leading to clearance of damaged mitochondria—but they tell us what can happen in a dish, not what happens in a living reproductive system under real-world conditions.
Urolithin A and Sperm Function
Two studies examined urolithin A’s effects on sperm. A 2024 study in cattle found that urolithin A influenced bovine sperm capacitation—the activation process sperm undergo before they can fertilize an egg—and affected in vitro fertilization outcomes in that model [5]. The authors suggest urolithin A may modulate mitochondrial activity and redox balance during sperm function, though the direction and magnitude of effects require further investigation before conclusions can be drawn for human sperm.
A 2026 rat study took a more clinically relevant angle, examining whether urolithin A could protect against sperm damage caused by diabetes. Diabetes is a known risk factor for male fertility problems, in part through increased oxidative stress in reproductive tissue. The study found that urolithin A supplementation was associated with protection against diabetes-induced pathospermia (abnormal sperm characteristics) and reduced embryotoxicity in diabetic rats [2]. This is notable because it suggests urolithin A may have relevance not only in aging but also under metabolic disease conditions—though results in rats are not directly transferable to clinical practice.
Protecting Ovarian Reserve: Chemotherapy Context
Ovarian reserve refers to the remaining supply of eggs a person has. It naturally declines with age, but certain cancer treatments—particularly alkylating chemotherapy agents—can dramatically accelerate this decline by inducing follicle apoptosis (programmed cell death). This is a recognized clinical problem for young cancer survivors who wish to preserve their fertility.
A 2025 study investigated whether urolithin A could protect ovarian reserve in a chemotherapy-treated mouse model. The researchers found that urolithin A was associated with better preservation of follicle counts and reduced apoptosis in ovarian tissue, and identified inhibition of the PI3K/Akt signaling pathway as a likely mechanism [3]. The PI3K/Akt pathway regulates cell survival decisions, and its dysregulation by chemotherapy is thought to contribute to follicle loss. These findings are preliminary and from a mouse model, but they open a question worth studying further: whether urolithin A or related compounds might one day play a role in fertility preservation strategies during cancer treatment.
The Gut Microbiome, Aging, and Reproductive Health
Because urolithin A is produced by gut bacteria rather than absorbed directly from food, individual microbiome composition affects how much urolithin A a person produces after eating polyphenol-rich foods. A 2026 review examined what researchers are calling the gut-extracellular vesicle-mitochondria axis in the context of reproductive aging [6]. The authors describe a proposed pathway by which gut-derived signals—potentially including urolithin A—may influence mitochondrial health in reproductive tissues through extracellular vesicles, small particles that carry molecular cargo between cells.
This mechanistic picture is still being assembled. The review highlights antioxidant and anti-senescence pathways as candidates, but the gut-to-ovary or gut-to-testis signaling chain in humans has not been directly demonstrated in clinical research. It does, however, situate urolithin A within a broader question about how gut health relates to reproductive aging—a question that is becoming more tractable as microbiome research matures.
What the Evidence Does Not Yet Tell Us
It is important to be direct about the gap between these findings and clinical guidance on fertility. Every study cited here was conducted in animals (rats, mice, cattle, pigs) or in laboratory cell models—not in humans. Animal models can establish plausible biological mechanisms and guide future research, but they frequently fail to translate directly into human clinical benefit. No human randomized controlled trials have tested whether urolithin A supplementation improves fertility outcomes, egg quality, sperm parameters, or ovarian reserve in people.
There is also the question of dose and bioavailability. The amounts of urolithin A used in laboratory studies may not match what is achievable through diet alone, and individual variation in gut microbiome composition means that dietary polyphenol intake produces very different urolithin A levels in different people. Standardized urolithin A supplements bypass this conversion step, but whether any dose is safe or effective for reproductive purposes in humans is not yet established.
For people with active fertility concerns—whether related to aging, cancer treatment, metabolic disease, or otherwise—the appropriate step is consultation with a reproductive endocrinologist or fertility specialist, not supplementation based on preclinical data.
🛒 Where to Buy Urolithin A
- Timeline Mitopure SoftgelsClinically studied
softgels, 500 mg/day — The clinically studied form (Amazentis); used in the human trials. - Pure Encapsulations Renual
caplique capsules, 250 mg Mitopure Urolithin A/serving (with resveratrol + CoQ10) — established clinical-supplement brand, third-party tested. - ProHealth Longevity Urolithin A
capsules, 500 mg — Longevity-focused brand, often higher dose. - Double Wood Urolithin A
capsules, 250-500 mg — Budget-friendly, widely available, COA on request.
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A Note on the Evidence
All reproductive research on urolithin A reviewed here comes from animal models or laboratory cell studies—no human clinical trials on fertility have been completed. This article is for informational purposes only and does not constitute medical advice; anyone with concerns about fertility, ovarian reserve, or reproductive health should consult a qualified healthcare provider before making any supplement decisions.
Frequently Asked Questions
Does urolithin A improve fertility in humans?
There is no human clinical trial evidence to support this claim. The current research is limited to animal models and laboratory cell studies. While these findings suggest biologically plausible mechanisms, they cannot be used to make claims about human fertility outcomes.
How might urolithin A affect egg quality?
In laboratory models, urolithin A has been associated with reduced oxidative stress and improved mitochondrial function in bovine and porcine oocytes [4][1]. Mitochondrial health is important for egg maturation and early embryo development, but whether these effects occur in human eggs has not been studied.
Is there research on urolithin A and sperm?
Yes, at the preclinical level. A rat study found urolithin A was associated with protection against diabetes-related sperm damage [2], and a bovine study examined effects on sperm capacitation and in vitro fertilization [5]. Neither study involved human subjects.
Can urolithin A protect ovarian reserve during chemotherapy?
A 2025 mouse study found that urolithin A was associated with better follicle preservation and reduced apoptosis in chemotherapy-treated animals, potentially through effects on PI3K/Akt signaling [3]. This is early preclinical evidence; no clinical trials in cancer patients have been conducted. Anyone concerned about fertility preservation during cancer treatment should speak with a reproductive specialist before treatment.
How does the gut microbiome connect to reproductive health and urolithin A?
Because urolithin A is produced by gut bacteria from dietary polyphenols, microbiome composition determines how much of it a person generates. A 2026 review describes proposed pathways by which gut-derived signals may influence mitochondrial health in reproductive tissues [6], though this signaling chain has not been directly confirmed in humans.
Should someone trying to conceive take urolithin A?
There is no clinical evidence basis for recommending urolithin A specifically to improve conception chances. The existing research is animal-based and preliminary. Anyone trying to conceive, especially those facing fertility challenges, should consult a reproductive endocrinologist for guidance tailored to their situation.
References
- Shi W et al. Urolithin A Protects Porcine Oocytes from Artificially Induced Oxidative Stress Damage to Enhance Oocyte Maturation and Subsequent Embryo Development. International journal of molecular sciences (2025). PMID 40243704
- Haddadi-Salmasi R et al. Urolithin A safeguards against diabetes-induced pathospermia and embryotoxicity in rats. Avicenna journal of phytomedicine (2026). PMID 42153016
- Wang W et al. Urolithin A Protects Ovarian Reserve Via Inhibiting PI3K/Akt Signaling and Preventing Chemotherapy-Induced Follicle Apoptosis. Biology (2025). PMID 40723388
- Fonseca É et al. Anti-Aging Effect of Urolithin A on Bovine Oocytes In Vitro. Animals : an open access journal from MDPI (2021). PMID 34359176
- Jorge M et al. Effect of Urolithin A on Bovine Sperm Capacitation and In Vitro Fertilization. Animals : an open access journal from MDPI (2024). PMID 39335315
- Moustakli E et al. The Gut-Extracellular Vesicle-Mitochondria Axis in Reproductive Aging: Antioxidant and Anti-Senescence Mechanisms. Antioxidants (Basel, Switzerland) (2026). PMID 41750555
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.