Urolithin A shows positive effects on muscle strength and endurance in middle-aged and older adults across several small RCTs, but the evidence remains preliminary because virtually all studies were funded by the manufacturer and independent replication is lacking. No effect on energy production in the muscle (ATP production) has been demonstrated. Those who wish to try it can reasonably consider 1000 mg per day, but should be aware that the research is still at an early stage.
Urolithin A is a compound produced by gut bacteria from ellagitannins, substances that occur naturally in pomegranates, walnuts and raspberries. Because not everyone produces sufficient amounts of it on their own, urolithin A is also available as a supplement (under the brand name Mitopure). The mechanism is biologically plausible: urolithin A stimulates mitophagy, the process by which cells clear out and replace damaged mitochondria, and it suppresses low-grade chronic inflammation. In several clinical studies, researchers observed significantly lower inflammatory markers (CRP) and plasma acylcarnitines, as well as upregulation of mitochondrial genes and autophagy markers in human muscle tissue.
For muscle function, there are early positive results from randomised, placebo-controlled studies in humans. In middle-aged adults who took 500 to 1000 mg of urolithin A per day for four months, muscle strength improved by approximately 12% compared with placebo. In older adults aged 65 to 90, muscle endurance in both hand and leg muscles improved significantly after just two months. These are clinically relevant outcomes, although the studies are relatively small.
There are also clear limits to what urolithin A does. On the primary endpoint of the study in middle-aged adults, namely peak power output, there was no significant effect. The same applies to maximal ATP production in the hand muscle, measured by MR spectroscopy in older adults. The 6-minute walk test improved numerically but not statistically significantly. No demonstrable effect was found on body composition, cardiovascular outcomes or gut microbiome composition either. In short: an effect on energy production in the muscle has not yet been demonstrated, while the effect on strength and endurance does turn out to be positive.
Safety is not a major concern: across several clinical studies at doses of 500 to 1000 mg per day, the safety profile was favourable. Side effects were mild to moderate and were not attributed to the supplementation itself.
A serious caveat is nevertheless needed. Virtually all clinical studies have been conducted by or in close collaboration with Amazentis SA, the manufacturer of Mitopure. Independent replication by unaffiliated research groups is largely absent. This does not mean the results are incorrect, but it is reason to regard the findings as preliminary until independent research confirms them. In animal models of Duchenne muscular dystrophy, urolithin A improved muscle function and extended survival, but this has not yet been translated into clinical trials in humans.
Based on several small to medium-sized RCTs and a systematic review (PMID 35584623, 35050355, 32694802, 39002645). Animal research for DMD (PMID 33827972). Almost all clinical data originate from or were sponsored by the manufacturer Amazentis SA.