What Is the Gut Microbiome?
Your gut is home to trillions of microbes that do far more than digest food. One of their quieter talents is chemistry: certain species take compounds you eat and transform them into molecules your own cells could never make. Urolithin A is a striking example, and whether your body produces it depends on the community living inside you.
What the gut microbiome actually is
The gut microbiome is the collective term for the bacteria, archaea, fungi, and viruses that live throughout your digestive tract, concentrated most densely in the large intestine. Estimates put the number of microbial cells on roughly the same order as the number of human cells in your body, and the genes those microbes carry outnumber your own by a wide margin. Because of that genetic diversity, the microbiome behaves like an extra metabolic organ. It ferments dietary fiber your enzymes cannot break down, produces short-chain fatty acids that feed the cells lining your colon, helps synthesize certain vitamins such as vitamin K and several B vitamins, and trains the immune system to tell friend from foe.
No two microbiomes are identical. The mix of species you carry is shaped by genetics, birth mode, early-life diet, geography, medications (antibiotics in particular), fiber intake, and age. This individuality is central to understanding why the same food can produce very different results in two different people, which is exactly the case with urolithin A.
How gut bacteria make urolithin A
Urolithin A is not found in any food directly. It is a postbiotic, meaning a compound produced by your gut bacteria from raw material you supply. That raw material is a family of large polyphenols called ellagitannins, along with their breakdown product ellagic acid. Ellagitannins are abundant in pomegranate, walnuts, and certain berries such as raspberries and strawberries.
When you eat these foods, the ellagitannins travel largely intact to the lower gut, because they are too big to be absorbed in the small intestine. There, specific bacteria go to work, stripping and rearranging the molecule through a multi-step process until it becomes urolithin A, a small compound your body can absorb into the bloodstream. Research has identified members of the Gordonibacter genus, including Gordonibacter urolithinfaciens, and the species Ellagibacter isourolithinifaciens, among the gut bacteria capable of carrying out key steps in this conversion. The full pathway appears to involve a relay of species rather than a single organism, which is part of why it is so variable from person to person.
The evidence, organized honestly
Proven in humans
The safety and biological activity of urolithin A itself have been studied in people. The first-in-human trial by Andreux and colleagues, published in Nature Metabolism in 2019, reported that oral urolithin A was safe and well tolerated at doses up to 1,000 mg per day and shifted mitochondrial gene-expression signatures in older adults. Later randomized human trials built on this: Liu, D'Amico and colleagues (JAMA Network Open, 2022) reported improved muscle endurance in older adults over roughly four months, and Singh and colleagues (Cell Reports Medicine, 2022) tested 500 mg and 1,000 mg arms in middle-aged adults over four months, observing effects on muscle strength and exercise performance. These are human findings about the compound; they are not claims that eating pomegranate produces the same result.
Newer human research
More recent human work has widened the picture. A 2024 randomized trial in the Journal of the International Society of Sports Nutrition studied resistance-trained men over eight weeks, and a 2025 randomized controlled trial published in Nature Aging reported that urolithin A supported immune-cell mitochondrial health in midlife adults across roughly 28 days, a line of research connected to so-called inflammaging. A 2024 systematic review in Ageing Research Reviews, titled 'Targeting aging with urolithin A in humans,' offers a measured summary: the human evidence is genuinely promising but still emerging, and larger, longer studies are needed.
Preclinical foundations
Much of the original mechanistic work was done in laboratory models and should be read as preclinical. Ryu and colleagues (Nature Medicine, 2016) showed that urolithin A induced mitophagy, extended lifespan in the worm C. elegans, and improved muscle function in rodents. Preclinical research is also exploring roles in areas such as joint and cartilage biology (D'Amico and colleagues, Aging Cell, 2022), and early work is examining skin, gut, brain, and heart tissue. These animal and cell findings are informative for understanding mechanism, but they have not been confirmed in humans and should not be treated as established human benefits.
Why converter status matters
Because the conversion of ellagitannins to urolithin A depends on carrying the right bacteria, researchers describe people as different metabotypes: some produce urolithin A readily, some produce related metabolites, and some produce very little. Diet, antibiotic history, and the sheer individuality of the microbiome all feed into this. It means that two people eating identical amounts of pomegranate can end up with very different urolithin A levels in their blood. For anyone counting on food alone to raise urolithin A, this is a real and underappreciated limitation. If you want to explore the food route, our overview of foods high in urolithin A covers the best dietary sources of the precursors.
Supporting your microbiome, sensibly
A few habits are broadly associated with a diverse, resilient microbiome, though none is a guarantee of urolithin A production. Eating a wide range of plants and plenty of fiber gives your bacteria more to work with. Fermented foods add microbial variety. Using antibiotics only when genuinely needed helps preserve the community. And limiting ultra-processed foods reduces disruption. These are sensible general practices for gut health rather than a reliable lever for a specific postbiotic. This guide is educational and is not a treatment for any gut, digestive, or other medical condition; if you have ongoing digestive symptoms, please see your doctor.
If your goal is specifically to raise urolithin A, the most direct route is the finished compound. That is the logic behind our complete urolithin A guide and our roundup of the best urolithin A gummies, which walk through what to look for. You can also read more on the underlying biology in our explainer on mitochondrial health.
Frequently asked questions
Does everyone produce urolithin A from food?
No. Production depends on carrying specific gut bacteria capable of converting ellagitannins. Studies describe distinct metabotypes, and a meaningful share of people produce little urolithin A even when they eat pomegranate or walnuts regularly.
Which bacteria make urolithin A?
Research has identified members of the Gordonibacter genus and the species Ellagibacter isourolithinifaciens as able to perform key steps. The complete pathway seems to involve several species working in relay, which helps explain the person-to-person variability.
Can I improve my ability to make urolithin A?
A diverse, fiber-rich diet supports overall microbiome diversity, but there is no proven way to guarantee you become a urolithin A producer. If raising urolithin A is the goal, taking the finished postbiotic sidesteps the conversion question entirely.
Is a supplement different from eating pomegranate?
Yes. Pomegranate supplies ellagitannin precursors that your bacteria may or may not convert. A urolithin A supplement provides the finished compound directly, so the amount you absorb does not depend on your microbiome.
Is urolithin A safe?
In human research, oral urolithin A was reported to be safe and well tolerated at doses up to 1,000 mg per day. As with any supplement, talk to your healthcare provider before starting, especially if you are pregnant, nursing, or taking medication.
How much urolithin A has been studied?
Human trials have generally used 500 to 1,000 mg per day, with 1,000 mg being the top of the studied range. SOMA HEALTH Urolithin A Gummies provide 1,000 mg in a four-gummy daily serving.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. This guide is educational and is not a substitute for advice from a qualified healthcare provider.
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