Urolithin A

Overview

Urolithin A is a postbiotic compound your gut bacteria make from the ellagitannins in pomegranates, walnuts, and berries, and it's the most-studied natural activator of mitophagy, your cells' system for clearing out worn-out mitochondria. The catch: most people's gut bacteria can't produce a meaningful amount, which is the entire reason direct supplementation exists.

What is Urolithin A?

Urolithin A (UA) is a compound your gut bacteria produce when they break down ellagitannins and ellagic acid, the polyphenols found in pomegranates, walnuts, and certain berries. Here is the part that surprises most people: you do not eat Urolithin A. It is not in any food. It is a postbiotic — a metabolite your microbiome manufactures downstream, assuming you happen to have the right bacteria for the job.

Most people don't. Or at least, not enough of them. Researchers have mapped this variation into what they call "urolithin metabotypes." Roughly 1 in 10 adults are metabotype 0 and produce essentially none, and the ability to make meaningful amounts steadily declines with age (Cortés-Martín et al., 2018, Food & Function, an 839-person cohort showing aging is the primary driver of metabotype). Even the good converters only turn a small fraction of the precursors they eat into UA. So whether you actually benefit from pomegranates the way the headlines promise comes down to a microbiome lottery you didn't choose.

UA went from obscure polyphenol metabolite to one of the most-studied longevity compounds in the world after a landmark 2016 paper showed it triggers mitophagy — the cellular cleanup of damaged mitochondria — and extends lifespan in worms while improving muscle function in rodents (Ryu et al., 2016, Nature Medicine). Since then, multiple human trials have confirmed it is safe at clinically relevant doses and that it produces measurable improvements in muscle strength, muscle endurance, and mitochondrial biomarkers.

The thesis of this page is simple. Urolithin A is the best-evidenced natural mitophagy activator we have. The human data is genuinely promising for muscle and mitochondrial health. And because the food-to-UA conversion is broken for most people, supplementing the finished compound is the only way to reliably get a clinical dose.

Key Takeaway

• Urolithin A is a postbiotic — your gut makes it from pomegranate, walnut, and berry compounds. You don't get it directly from any food.
• Only a minority of people produce meaningful amounts. About 1 in 10 make almost none, and production drops as you age.
• It's the most-studied natural activator of mitophagy, the cellular cleanup that clears out damaged mitochondria.
• Human trials used 500 mg or 1,000 mg daily, with benefits showing up over 2 to 4 months, not days.
• The strongest human evidence is for muscle strength, muscle endurance, and mitochondrial biomarkers in middle-aged and older adults.
• Lifespan extension has been shown in worms and rodents, not humans. We're not going to pretend otherwise.
• Direct supplementation skips the gut-conversion lottery entirely and delivers a consistent dose.

Where it comes from (and why "just eat pomegranates" doesn't really work)

Be precise here, because the internet is awash in "eat pomegranates for Urolithin A" advice that is, generously, half true. The foods that contain the precursors are pomegranate (juice and arils), walnuts, pecans, raspberries, strawberries, blackberries, and oak-aged red wines. All of them deliver ellagitannins and ellagic acid. None of them contain Urolithin A itself. Your gut has to make the conversion.

Do the honest math. A typical glass of pomegranate juice delivers a modest amount of precursor, and even an efficient converter turns only a slice of that into UA — well, well short of the 500 mg used in human trials. A non-converter (metabotype 0) gets close to zero no matter how many pomegranates they put in the blender. Compare it to vitamin D, where you can at least theoretically eat your way to a respectable intake with enough wild salmon. With Urolithin A you basically can't, and most people can't convert efficiently anyway.

That is the entire reason finished-compound supplementation exists. Research shows that directly supplementing Urolithin A produces consistent UA blood levels across the population regardless of microbiome type (Singh et al., 2022, European Journal of Clinical Nutrition). You stop depending on a biological pipeline that may or may not be wired up correctly inside you.

If you want the cellular-level mechanism, head to our deep dive on how Urolithin A activates mitophagy.

How it works

From food to compound

Ellagitannins from food get hydrolyzed into ellagic acid in your gut. From there, specific bacteria — mainly the Gordonibacter and Ellagibacter genera — convert ellagic acid through a series of steps into urolithins, including Urolithin A. If you don't carry enough of those bacteria, the pipeline stalls and you produce little to no UA. This is the metabotype story, and it's why two people eating the same handful of walnuts can end up with wildly different UA levels in their bloodstream.

What mitophagy actually is

Your cells are full of mitochondria, the tiny engines that turn fuel into usable energy. Over time some of them break down and turn into inefficient, leaky junk. Mitophagy is your cells' quality-control system: it tags damaged mitochondria, hauls them off to be dismantled, and recycles the parts. The problem is that mitophagy slows down as you age — right when you're accumulating the most damaged mitochondria. The junk piles up. Energy output drops. Think of a busy kitchen where someone finally stopped taking out the trash; eventually nothing works the way it should.

How Urolithin A fits in

Urolithin A enters cells and nudges that cleanup process back into gear. By promoting mitophagy, it helps clear out damaged mitochondria, which makes room for the cell to build fresh, efficient ones — a process called mitochondrial biogenesis. The net effect researchers measure is improved mitochondrial efficiency. It is not a stimulant. It is not adding energy from the outside. It is helping your cells do maintenance they are supposed to be doing on their own but increasingly aren't.

Why muscle is where we see it first

Skeletal muscle is packed with mitochondria and burns through a lot of energy, so it's the easiest tissue in which to measure effects. That's why the human trials center on leg strength, walking endurance, and mitochondrial protein expression in muscle biopsies — those are the cleanest readouts. Mitochondria-rich tissues throughout the body share the same machinery, which is why researchers are also studying UA for broader cellular-health applications. But muscle is where the human evidence is strongest today.

The full pathway: Ellagitannins (pomegranate / walnuts / berries) → Gut bacteria convert → Urolithin A → enters cells → Mitophagy (clears damaged mitochondria) → Mitochondrial biogenesis (builds new ones) → improved cellular energy.

Want the deep version with PINK1 / Parkin signaling and the cellular-health detail? See How Urolithin A Activates Mitophagy.

Clinical evidence

• Urolithin A induces mitophagy and prolongs lifespan in C. elegans and increases muscle function in rodents — The foundational paper that put Urolithin A on the map. Identified UA as a first-in-class natural compound that induces mitophagy in vitro and in vivo. In C. elegans, it prevented the buildup of dysfunctional mitochondria and extended lifespan. In two mouse models of age-related decline, it improved exercise capacity. This is the result that launched the entire research program.
• The mitophagy activator urolithin A is safe and induces a molecular signature of improved mitochondrial and cellular health in humans — First-in-human trial in healthy, sedentary elderly adults. UA showed a favorable safety profile (the primary outcome), was bioavailable at all doses tested, and at 500 mg and 1,000 mg over 4 weeks shifted plasma acylcarnitines and skeletal-muscle mitochondrial gene expression toward a molecular signature of improved mitochondrial health.
• Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomized trial in middle-aged adults — The ATLAS trial. Randomized, double-blind, placebo-controlled trial in 88 overweight, low-fitness middle-aged adults (40–64) at 500 mg and 1,000 mg for 4 months. Leg muscle strength improved roughly 12% versus placebo, with clinically meaningful gains in aerobic endurance and 6-minute walk distance, and lower CRP and acylcarnitines. Candor: the trial did not hit its primary endpoint (peak power output) even though it hit several secondary endpoints.
• Effect of urolithin A supplementation on muscle endurance and mitochondrial health in older adults: a randomized clinical trial — Randomized clinical trial in older adults testing UA on muscle endurance and mitochondrial health. Found improvements in muscle endurance and favorable changes in mitochondrial biomarkers with supplementation, reinforcing the muscle-and-mitochondria thesis in an older population.
• Direct supplementation with Urolithin A overcomes limitations of dietary exposure and gut microbiome variability in healthy adults — Demonstrated that directly supplementing finished Urolithin A produces consistent UA blood levels across people regardless of whether they are natural converters — overcoming the limitations of dietary intake and the gut-microbiome lottery. This is the study that justifies finished-compound supplementation over pomegranate extract.
• Where to Find a Mammalian Urolithin: A Cross-sectional Study from 20 Different Cohorts (n=839) — In a cohort of 839 people aged 5–90, the gut bacteria responsible for converting ellagic acid into urolithins vary widely between individuals, and aging is the main factor shaping which 'metabotype' you fall into. A subset of adults — roughly 1 in 10 — produce essentially no urolithins at all, no matter how much pomegranate they eat.

Dosage & forms

• Standalone Urolithin A capsules, 500 mg:
• Higher-dose Urolithin A, 1,000 mg:
• Urolithin A powder:
• Pomegranate / ellagitannin extracts marketed as 'Urolithin A support':
• UA combined with protein or collagen:

Safety & interactions

Urolithin A has a favorable safety profile in clinical trials. The first-in-human study made safety its primary outcome and found UA well tolerated at single and repeated doses up to 1,000 mg, and later trials ran 500 mg and 1,000 mg daily for up to 4 months without serious adverse events (Andreux et al., 2019, Nature Metabolism; Singh et al., 2022, Cell Reports Medicine). It's a compound your own gut already produces in smaller amounts, which is part of why it behaves so benignly in supplemental form.

Side effects

Reported side effects in trials were minimal and generally mild — occasional digestive upset is the most common thing people mention anecdotally. There is no established pattern of serious side effects at the doses studied. Be honest about the limit: long-term data beyond several months is still limited because the published human research on Urolithin A is, in the grand scheme, young.

Who should be cautious

• Pregnant or nursing women — UA has not been studied in pregnancy or lactation. The responsible answer is to avoid it.
• Anyone on prescription medication or managing a medical condition — not because there's a known dangerous interaction, but because the interaction data simply isn't well characterized yet. When the data is thin, the honest move is "ask your doctor," not "trust us."
• Children — the research is in adults; this isn't a kids' supplement.

Drug interactions

This is a low-data area, so we're going to be candid about what we know and don't know.

The honest framing: Urolithin A's safety record in trials is reassuring, and there are no well-documented dangerous interactions. But "no documented interaction" is not the same as "proven safe with everything," because the research base is still being built. If you take medication, manage a health condition, or are pregnant or nursing, talk to your healthcare provider before starting. That's not boilerplate — it's the right call when the long-term data is still being written.

When to stop and see a doctor

Stop and check in with a provider if you develop persistent digestive distress, or any unusual symptom that starts after you begin supplementation. Trust your body over the label.

Buying guide

What to look for in a quality Urolithin A supplement

1. A dose that matches the research. The human trials used 500 mg and 1,000 mg. If a product hides behind 100–250 mg, or won't even tell you the milligrams, it's not giving you what was actually studied. 500 mg is the sweet spot for daily use.

2. Single ingredient, fully disclosed. You want to see "Urolithin A 500 mg" right on the Supplement Facts panel — not a "proprietary longevity blend" that could be mostly filler with a sprinkle of the expensive stuff. Proprietary blends exist to hide how little of the good ingredient you're actually getting.

3. Not a pomegranate extract in disguise. This is the big one. Plenty of products market themselves around Urolithin A but actually contain ellagic acid or pomegranate extract — the precursors. Those still rely on your gut to do the conversion you may not be able to do. If you specifically want Urolithin A, buy Urolithin A.

4. Third-party tested, made under cGMP. Independent testing confirms the label matches what's in the bottle and screens for contaminants. cGMP manufacturing is table stakes for any supplement worth taking.

5. Be realistic about price. Urolithin A is one of the most expensive raw materials in the supplement world right now. A suspiciously cheap "Urolithin A" product is usually a tell — either it's underdosed or it's a precursor extract wearing a costume. You get what the molecule actually costs.

Our approach at Mt. Angel Vitamins

We've been manufacturing supplements in Mt. Angel, Oregon for over 50 years. Our Urolithin A 500mg is a single-ingredient capsule at the clinically studied 500 mg dose, made and tested in our own cGMP facility, with every batch third-party verified. A bottle is a 60-day supply, not 30.

Credit where it's due: Timeline's Mitopure is the branded form behind much of the published Urolithin A research, and the science they've funded is excellent. We just believe in a clean single-ingredient capsule at the real dose, made in our own facility, at an honest per-day cost.

Frequently asked questions

What is Urolithin A?

Urolithin A is a postbiotic compound your gut bacteria produce when they break down the ellagitannins found in pomegranates, walnuts, and berries. It isn't in food directly — your microbiome makes it, if you have the right bacteria. It's the most-studied natural activator of mitophagy, the process your cells use to clear out damaged mitochondria and build fresh ones. Because most people can't produce meaningful amounts on their own, it's typically taken as a supplement to get a consistent, clinically relevant dose.

What are the benefits of Urolithin A?

The strongest human evidence is for muscle strength, muscle endurance, and mitochondrial health, mostly in middle-aged and older adults. In a 4-month randomized trial, 500 mg and 1,000 mg daily improved leg strength by roughly 12% versus placebo and improved walking endurance and mitochondrial biomarkers. It works by reactivating mitophagy, your cells' cleanup system for worn-out mitochondria. Benefits build over months, not days. Lifespan extension has been shown in worms and rodents, but not yet proven in humans.

Can't I just eat pomegranates or take pomegranate extract instead?

Probably not effectively. Pomegranates, walnuts, and berries contain the precursors (ellagitannins), not Urolithin A itself. Your gut bacteria have to convert them, and research shows only a minority of people convert efficiently. Roughly 1 in 10 adults produce almost none, and conversion declines with age. Even good converters get a fraction of the 500 mg used in studies. Pomegranate extract supplements have the same problem — they deliver precursors, not the finished compound. Supplementing Urolithin A directly skips the conversion step entirely.

How much Urolithin A should I take?

The human trials used 500 mg and 1,000 mg daily. 500 mg is the standard maintenance dose and captures most of the measured mitophagy benefit, which makes it the best cost-to-benefit choice for daily long-term use. 1,000 mg reaches the upper end of activation but adds only modest extra benefit for roughly double the cost. Take it once daily, consistently. For the full breakdown of where the benefits plateau, see our dose-response analysis.

How long does Urolithin A take to work?

Think months, not days. The published clinical trials measured significant improvements in muscle and mitochondrial markers after 2 to 4 months of daily use. This isn't a stimulant — you won't feel a jolt. It works by gradually reactivating your cells' mitochondrial cleanup process, and that's a slow, cumulative change. Most quality products are sold as 60-day supplies for exactly this reason. Give it a consistent two to four months before judging results.

Is Urolithin A safe? What are the side effects?

Urolithin A has a favorable safety profile in clinical trials. The first-in-human study made safety its primary goal and found it well tolerated, and later trials ran 500 mg and 1,000 mg daily for up to 4 months with no serious adverse events. Reported side effects are minimal, with occasional mild digestive upset being the most common complaint. Long-term data beyond several months is still limited. If you're pregnant, nursing, on medication, or managing a condition, check with your healthcare provider first.

Does Urolithin A really slow aging or extend lifespan?

In animals, yes — in humans, not proven yet. Urolithin A extended lifespan in C. elegans (worms) and improved muscle function in aged mice in the foundational research. In humans, the trials show improvements in muscle strength, endurance, and mitochondrial health, which are markers tied to healthy aging, but no study has shown UA extends human lifespan. We think the honest framing is 'promising for cellular and muscle health as you age,' not 'anti-aging miracle.' The science is encouraging and still early.

How is Urolithin A different from NMN, NR, or CoQ10?

They all target cellular energy but through different doors. Urolithin A works on mitophagy — clearing out and recycling damaged mitochondria so your cells can build new ones. NMN and NR are precursors to NAD+, a coenzyme involved in energy metabolism and cellular repair. CoQ10 works inside the mitochondrial electron transport chain itself, helping convert fuel into energy. They're complementary rather than interchangeable, and there's no known problem combining them, though more isn't automatically better.