Urolithin A

urolithin A · UA

A gut-derived metabolite that stimulates mitophagy, studied for muscle and mitochondrial health.

TypeSupplement / dietary

The grade answers: What does the human evidence support for: Mitochondrial & muscle function?

Grade

Limited

The grade rates evidence quality — it is not advice to take or buy.

Class: Mitophagy
Primary use: Mitochondrial & muscle function
Evidence strength: medium
Last reviewed: 2026-07-01

Bottom line

Unusual among supplements in having actual human RCTs — small ones showing better mitochondrial and muscle-endurance markers. Reasonably evidenced for muscle function; broad longevity claims are still a stretch.

What the evidence says

Urolithin A is produced by gut bacteria from ellagitannins in pomegranate and walnuts, but many people convert poorly, which is the rationale for taking it directly. Several randomized human trials report improved mitochondrial gene expression and muscle endurance or strength markers in middle-aged and older adults — generally on surrogate endpoints rather than hard clinical outcomes. That puts it above most supplements on evidence quality, yet it stays at grade C because the trials are small and the outcomes intermediate. It's a good example of 'better evidenced than average' still not meaning 'proven to extend life'.

Key studies

[1]
Urolithin A, mitophagy and muscle endurance (randomized trials) · RCT
Improved mitochondrial markers and muscle endurance on surrogate endpoints.
Open on PubMed ↗
[2]
Urolithin A safety and pharmacokinetics in humans · RCT
Well tolerated; establishes dosing feasibility.
Open on PubMed ↗
[3]
Urolithin A and mitochondrial health (review) · review
Synthesises the mitophagy rationale and early human data.
Open on PubMed ↗

See all studies on PubMed ↗

Scoped PubMed search, not a curated bibliography: the individual PMIDs for this entry have not yet been verified one by one. For that reason it is not used to support a high grade and is awaiting review.

Mechanism

Induces mitophagy — the recycling of damaged mitochondria — improving mitochondrial quality control, with downstream effects on muscle bioenergetics.

Safety

Well tolerated in human trials at the doses studied; safety has been characterised over months rather than years.

Dosage context

Human trials commonly use ~500–1000 mg/day of a defined form. Eating pomegranate or walnuts does not reliably produce equivalent urolithin A because gut-microbiome conversion varies widely between people.

Examples of application

Taken as a defined dose (~500–1000 mg/day), since gut conversion varies.
Aimed at muscle and mitochondrial support, often alongside training.
Pomegranate and walnuts don't reliably produce the same amount.

From the field

Urolithin A is a rare case: a supplement that actually ran randomized human trials. We still hold it at C, because 'better muscle-endurance markers in small trials' is not the same as 'lives longer'.

Related molecules

NMNB

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