What does urolithin A do to your muscles and mitochondria?
Urolithin A shows positive effects on mitochondrial health and muscle strength in small studies, but the evidence is still limited; larger independent trials are lacking, so treat the promising claims with appropriate scepticism.
Urolithin A is a compound produced by gut bacteria from nutrients found in pomegranate, berries, and nuts. It stimulates mitophagy: the process by which cells clear out and replace damaged mitochondria. That this works has been demonstrated in animal and cell studies, and to a limited extent also in human muscle and blood research.
In healthy, sedentary older adults who took 500 or 1000 mg per day for four weeks, measurable mitochondrial markers in blood and muscle tissue changed noticeably. That was a safety study, and the primary conclusion was reassuring: up to 1000 mg per day for four weeks produced no side effects. Long-term safety has not yet been well studied.
After four months of use, muscle strength improved in middle-aged adults by approximately 12% compared to placebo. Aerobic endurance and walking distance also showed clinically meaningful gains, although the primary endpoint (maximum peak power) did not reach a statistical threshold. At the same time, inflammatory markers in the blood decreased and markers of fat metabolism in the mitochondria improved. These are encouraging early results, but they come from relatively small, short-duration studies.
Laboratory researchers also observe that urolithin A, through calcium signalling, triggers the formation of new mitochondria and inhibits cellular ageing, including in the roundworm C. elegans and in mammalian cells. In a mouse model of sepsis, it restored muscle strength and mitochondrial function after severe illness. Whether those findings translate to humans is unknown; clinical trials for this are lacking.
A practical caveat: several authors of review studies on urolithin A have financial ties to the manufacturer of the commercial supplement. That does not mean the results are incorrect, but it is a reason to read the promising tone of those reviews with a somewhat more critical eye. The clinical studies themselves are small and short in duration; larger independent trials are needed before firm conclusions can be drawn.
Based on two small randomised, placebo-controlled studies in humans (a safety study and an efficacy study), supplemented by animal, worm, and cell studies. Several authors of review articles have financial ties to Amazentis (manufacturer of Mitopure). No large independent RCTs are available.