How long should urolithin A be taken?

Four months — the duration of the published trial and the window over which effects were measured. Four to six week courses correspond to no published protocol for this molecule.

What effects are documented?

Roughly a 12% improvement in muscle strength versus placebo, clinically meaningful improvements in aerobic endurance and the six-minute walk test, lower acylcarnitines and CRP, and increased mitophagy proteins in muscle. The trial's primary endpoint, peak power output, was not met.

Can urolithin A come from diet?

Only indirectly. It is produced by gut microbiota from the ellagitannins in pomegranate, walnuts and berries. That conversion depends on microbiota profile — the metabotypes described by Tomás-Barberán 2014 — which makes dietary supply highly uneven between individuals.

No trial compares timing: studies administer one daily dose without specifying an optimal moment. Over a four-month course, consistency is what determines the outcome.

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Urolithin A: what dose, for how long, and what the trial actually measured

Published 8/20/2026 · by VEXTA Team

How much per day?

The reference trial for urolithin A is Singh 2022 (Cell Reports Medicine, DOI 10.1016/j.xcrm.2022.100633, registered as NCT03464500): randomised, placebo-controlled, in middle-aged adults, with two doses administered over four months — 500 mg and 1,000 mg per day.

Both doses produced measurable effects. The 500 mg daily dose is the one most formulations adopt, including ours: it is the lower of the two studied levels to show a signal, which makes it the rational starting point.

What the trial measured — and what it did not

This trial deserves to be quoted in full, including what failed. The published results:

Muscle strength: roughly +12% versus placebo, significant
Improvements judged clinically meaningful in aerobic endurance (peak VO₂) and physical performance (six-minute walk test)
No significant improvement in the study's primary endpoint, peak power output
Plasma acylcarnitines and C-reactive protein significantly lower
Significant increase in the expression of mitophagy-related proteins in skeletal muscle

A trial that misses its primary endpoint is still a trial whose secondary endpoints are informative — but it cannot be presented as a complete demonstration. That is the honest reading of the available literature.

How long is a course?

Four months. That is the trial duration, and the window over which effects were observed. The four- to six-week protocols frequently seen online correspond to no published trial on this molecule.

If you are evaluating urolithin A, set a 16-week window and decide in advance what you will observe — a load on a given exercise, a distance, a recovery time. A general impression over a fortnight will tell you nothing usable.

Why supplementation exists at all: the metabotype question

Urolithin A is not present as such in food. It is produced by the gut microbiota from the ellagitannins in pomegranate, walnuts and berries. That conversion depends on microbiota composition: Tomás-Barberán 2014 (Journal of Agricultural and Food Chemistry, DOI 10.1021/jf5024615) describes distinct metabotypes — not everyone produces the same urolithins from the same dietary intake.

That is the rationale for direct supplementation: it bypasses the microbial step and makes intake independent of gut profile.

Timing and tolerability

Trials use a single daily dose without comparing schedules. No data supports recommending mornings over evenings. As with any long course, the timing that matters is the one you will keep for four months.

Available tolerability data covers middle-aged adults over four months. It covers neither pregnancy, nor breastfeeding, nor drug interactions. Medical advice is recommended if you are on treatment.

Sources

Questions fréquentes

500 or 1,000 mg per day in a single dose: these are the two doses evaluated in the Singh 2022 trial (Cell Reports Medicine, four months). 500 mg/day is the lower level to show a signal and the one most formulations adopt.