what-is-urolithin-a

Vitality Supplements · Ingredient Guide

What is Urolithin A?

A complete guide to urolithin A — what it is, why it's called a postbiotic, the gut-microbiome reason not everyone produces it, where its dietary precursors come from, what "Mitopure" means, and what the research investigates.

Last updated June 2026 · Written by Vitality Supplements Editorial Team · ~2,400 words · 10 min read
Food supplement information — not medical advice
UK manufactured ISO/IEC 17025 batch tested 4.8★ from 2,400+ reviews Evidence-referenced
Quick answer
What is urolithin A?
Urolithin A is a postbiotic — a compound the body does not get directly from food but produces when certain gut bacteria convert dietary polyphenols called ellagitannins and ellagic acid (found in pomegranate, walnuts, raspberries and strawberries). It is the most-studied of the urolithins and is best known in research for its association with mitophagy, the cellular process of clearing out and recycling worn-out mitochondria. A purified, supplement form is sold under the branded ingredient name Mitopure. Crucially, not everyone's gut microbiome can make meaningful amounts — only an estimated 30–40% of people are efficient "producers" — which is the rationale for taking urolithin A directly. It is a food supplement in the UK with no authorised health claims.
Key takeaways
  • Urolithin A is a postbiotic the body makes from dietary ellagitannins, not a compound eaten directly.
  • Its precursors are found in pomegranate, walnuts, raspberries, strawberries and other berries.
  • It is studied in relation to mitophagy and mitochondrial health.
  • Only an estimated 30–40% of people produce useful amounts from food.
  • Direct supplementation (e.g. Mitopure) bypasses this microbiome variability.
  • It is a UK food supplement with no authorised health claims.
The basics

What urolithin A actually is

Here is the first thing that surprises people: urolithin A is not itself found in any food. You cannot eat it. It is a metabolite — a compound the body makes during digestion. What food does provide are its precursors: a group of plant polyphenols called ellagitannins, which the body first breaks down into ellagic acid, and which certain gut bacteria then convert, step by step, into urolithin A.

This is why urolithin A is described as a postbiotic — a beneficial compound produced by the activity of gut bacteria, rather than a nutrient absorbed directly from the plate. It is a member of a wider family of compounds called the urolithins, of which urolithin A is by far the most studied. Its closest relative, urolithin B, is produced by a different metabolic route — we compare the two in our guide to urolithin A vs urolithin B, and explain the lesser-known sibling in what is urolithin B.

You cannot eat urolithin A. Your gut bacteria build it from what you eat.
The research association

Urolithin A and mitophagy

The headline reason urolithin A draws so much research interest is its association with mitophagy. Mitochondria are the tiny structures inside cells that generate most of the body's energy, and like any hard-working machinery they wear out over time. Mitophagy is the cellular "housekeeping" process that identifies, clears out and recycles these damaged, worn-out mitochondria. Urolithin A is studied in relation to this process — which is why it is so often discussed in a longevity context, since the efficiency of mitochondrial maintenance is known to decline with age.

Because urolithin A is a food supplement carrying no authorised UK health claims, the honest framing is to describe what research has investigated — the relationship between urolithin A and mitophagy and mitochondrial biology — rather than to make any promise about what taking it will do for you.

Mitophagy
The headline association. Urolithin A is studied in relation to mitophagy — the process of identifying and recycling damaged or worn-out mitochondria.
Mitochondrial focus
Why longevity interest. Mitochondrial health tends to decline with age, which is why a compound studied in relation to mitochondrial maintenance attracts longevity research.
A postbiotic
Made, not eaten. Urolithin A is produced by gut bacteria from dietary precursors, rather than absorbed directly from food — the defining feature of a postbiotic.
Not a medicine
A food supplement. Urolithin A is sold as a food supplement in the UK and carries no authorised health claims. Research describes associations, not outcomes.
This is the important bit

Why your gut decides

Here is the part that makes urolithin A unusual. Because it has to be manufactured by gut bacteria rather than simply absorbed, how much urolithin A you actually end up with depends entirely on the bacteria you happen to carry. Two people can eat exactly the same pomegranate, and one will convert its ellagitannins into a meaningful amount of urolithin A while the other produces almost none. The food was identical; the microbiome was not.

Researchers describe people as urolithin A "producers" or "non-producers". The estimates vary, but only around an estimated 30–40% of people carry a gut microbiome that converts these precursors efficiently. For everyone else, eating pomegranate or walnuts simply does not translate into much circulating urolithin A — no matter how much they eat.

Same pomegranate, different gut bacteria, very different result.
30–40%
Estimated producersThe share of people whose microbiome converts precursors efficiently.
Postbiotic
Compound classA beneficial compound produced by gut-bacteria activity.
Ellagitannins
The precursorThe dietary polyphenols gut bacteria convert into urolithin A.
Direct
Why supplements existTaking urolithin A directly bypasses microbiome variability.

This person-to-person variability is precisely the rationale behind taking urolithin A directly. If your gut cannot reliably make it, supplementing with a purified, standardised form sidesteps the lottery of which bacteria you carry. That is the reason a direct form of urolithin A — branded Mitopure — was developed: to provide the compound itself, in a known amount, regardless of whether you are a natural producer or not.

Dietary precursors

Where the precursors come from

When people talk about "foods with urolithin A", what they really mean is foods rich in its precursors — the ellagitannins and ellagic acid that gut bacteria need as raw material. The standout source is the pomegranate (and pomegranate juice), which is the food most associated with urolithin A research. Beyond that, the precursors are concentrated in walnuts and in a range of berries — particularly raspberries and strawberries, along with other berries such as blackberries.

The crucial caveat bears repeating: these foods provide ellagitannins, not urolithin A itself. Whether eating them produces any meaningful urolithin A depends on your microbiome. For the estimated majority who are not efficient producers, a varied diet rich in these precursors still will not generate much of the postbiotic — which is the gap that direct supplementation is designed to fill.

  • Pomegranate & pomegranate juice — the food most associated with urolithin A research.
  • Walnuts — a notably rich source of ellagitannins.
  • Raspberries — among the highest-ellagitannin berries.
  • Strawberries — another well-known berry precursor source.
  • Other berries — such as blackberries, also contribute ellagitannins.
  • The caveat — these supply precursors, not urolithin A; conversion depends on your microbiome.
Common questions

Urolithin A FAQ

No. Urolithin A is not present in any food directly. What food provides are its precursors — the ellagitannins and ellagic acid found in pomegranate, walnuts and berries — which certain gut bacteria then convert into urolithin A. It is a postbiotic, made in the gut rather than eaten.
Both are urolithins — compounds made by gut bacteria from dietary ellagitannins. Urolithin A is the most studied of the family, notably for its association with mitophagy, while urolithin B is produced by a different metabolic route and is far less researched. We compare them in detail in urolithin A vs urolithin B.
Mitopure is a branded, purified form of urolithin A used in supplements. Rather than relying on the gut to convert dietary precursors, it provides a standardised dose of urolithin A directly — which is useful given that only an estimated 30–40% of people produce meaningful amounts from food.
No. Only an estimated 30–40% of people have a gut microbiome that converts ellagitannin precursors into urolithin A efficiently. For everyone else, eating precursor-rich foods produces little of the compound — which is the main reason direct supplementation exists.
Mitophagy is the cellular process of identifying, clearing and recycling damaged or worn-out mitochondria — the structures inside cells that produce most of their energy. It is the main research association of urolithin A, and the reason the compound is discussed in a longevity context.
It is taken as a food supplement that provides a direct, standardised dose, bypassing the need for the gut to make it. Because it is a food supplement with no authorised health claims, anyone who is pregnant, breastfeeding or taking medication should consult a qualified healthcare professional before starting.

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About the author. This guide was written and reviewed by the Vitality Supplements Editorial Team, a UK supplement manufacturer. Every batch we produce is independently tested by an ISO/IEC 17025-accredited laboratory, with a Certificate of Analysis available on request.

This article is for general information about food supplements and is not medical advice. Urolithin A is sold as a food supplement in the UK and carries no authorised health claims. Always consult a qualified healthcare professional before starting any supplement, particularly if you are pregnant, breastfeeding, taking medication or managing a health condition. References available on our research references page.