How Pomegranate Became a Gut Bacteria Story, 2007 to 2025
Pomegranate's urolithin A story runs through gut bacteria, not the juice bottle. This history follows ellagitannins from a 2007 pig study and a 2014 volunteer letter to the 2016 mitophagy paper and five human studies, with what each one measured.
Pomegranate's urolithin A story is a gut bacteria story, because the fruit's ellagitannins are not absorbed as such. Gut microbes break them down, and urolithin A is one of the products. The earliest study we could confirm dates to 2007. A 2014 letter summarizing several human trials found that 5 to 25 percent of volunteers produced none of the urolithins it tracked. ## How far back does pomegranate cultivation go? A 2023 chapter by two Tel Aviv University archaeologists lists pomegranate among the first fruit trees domesticated in southwest Asia and Europe, alongside olive, grapevine, fig and date palm. The authors date the start of that fruit-tree horticulture to about 7,000 years before present, and they argue that the central Jordan Valley may have been a primary area of domestication. They also call the early record fragmentary next to the grain evidence. [Langgut and Sasi, 2023](https://doi.org/10.1007/978-3-031-27330-8_3) ## Why does a pomegranate compound need gut bacteria? Ellagitannins are found in pomegranate, nuts and berries, according to [Ryu and colleagues](https://doi.org/10.1038/nm.4132). A 2007 study in Iberian pigs, which its authors used as a model for human ellagitannin metabolism, traced the chain. Ellagitannins released ellagic acid in the jejunum, then intestinal flora converted it in sequence to urolithin D, urolithin C, urolithin A and urolithin B. Urolithin A was the only metabolite the team detected in feces, and together with its glucuronide it was the most abundant metabolite in urine ([Espín and colleagues, 2007](https://doi.org/10.1021/jf0723864)). Ellagic acid sits earlier in that chain, and it has its own page: [ellagic acid](/ingredients/ellagic-acid). A 2025 running trial describes urolithin A the same way, as a metabolite that gut bacteria produce after people eat ellagitannin-rich foods ([Whitfield and colleagues](https://doi.org/10.1007/s40279-025-02292-5)). The bacteria a person carries decide how much of that metabolite they make from food, which is why the next section matters for every trial that follows. ## Why do people respond differently? A 2014 letter by [Tomás-Barberán and colleagues](https://doi.org/10.1021/jf5024615) sorted volunteers by which urolithins their gut made after ellagitannin and ellagic acid intake. Phenotype A made only urolithin A conjugates, the largest group at 25 to 80 percent of volunteers across the trials. Phenotype B made isourolithin A or urolithin B as well, at 10 to 50 percent. Phenotype 0 made none of the tracked urolithins, at 5 to 25 percent. The three groups appeared regardless of age, sex, body mass index, health status or food source. A higher share of phenotype B showed up in people with chronic illness tied to gut microbial imbalance, which the authors said deserves further research. The authors also said these phenotypes should be considered in any intervention trial of ellagitannins or ellagic acid. A trial that does not sort its volunteers can average a responder and a non-responder into a result that describes neither. That matters most for people who get urolithins from food. A capsule of urolithin A skips the conversion step, and Andreux and colleagues reported that urolithin A reached blood plasma at every dose they tested. ## What did the early human trials measure? Five human studies have tested urolithin A in adults. The table lists each one's population, dose and length, main outcomes, and result as the authors reported it. | Study | Who took part | Dose and length | What was measured | Result as reported | |---|---|---|---|---| | [Andreux et al., 2019](https://doi.org/10.1038/s42255-019-0073-4) | Healthy, sedentary older adults | Single dose, or 4 weeks at 500 or 1,000 mg | Safety (primary); plasma acylcarnitines and muscle mitochondrial gene expression | Favorable safety profile; biomarker changes at 500 and 1,000 mg | | [Liu et al., 2022](https://doi.org/10.1001/jamanetworkopen.2021.44279) | 66 adults aged 65 to 90 | 1,000 mg a day or placebo for 4 months | 6-minute walk and hand-muscle ATP (primary); muscle endurance (secondary) | Primary endpoints not significant; muscle endurance improved versus placebo at 2 months | | [Singh et al., 2022](https://doi.org/10.1016/j.xcrm.2022.100633) | Middle-aged adults | Two doses for 4 months | Peak power output (primary); muscle strength, VO2 peak, 6-minute walk | Strength rose about 12%; primary endpoint not significant | | [Denk et al., 2025](https://doi.org/10.1038/s43587-025-00996-x) | 50 healthy middle-aged adults | 1,000 mg a day or placebo for 4 weeks | T-cell subsets and immune cell metabolism (primary) | Expanded a naive-like group of CD8 T cells and raised their fatty acid oxidation capacity | | [Whitfield et al., 2025](https://doi.org/10.1007/s40279-025-02292-5) | 42 male distance runners | 1,000 mg a day or placebo for 4 weeks at altitude | 3,000 m time trial, exertion ratings, a muscle-damage marker | No faster time trial in either group; lower exertion and muscle-damage marker with urolithin A | The studies were small. The runner trial enrolled 42 men, the immune trial 50 adults and the older-adult muscle trial 66. Four of the five abstracts list a ClinicalTrials.gov registration number, so readers can compare planned endpoints with the published ones. Three of the five found no significant gain on their main performance measure. The muscle endurance result in Liu and colleagues was a secondary endpoint, not the primary one. Three of the studies ran four weeks, and two ran four months. Safety is the steadier part of the record. Liu and colleagues found no statistical difference in adverse events between groups, and Andreux and colleagues reported a favorable safety profile in healthy, sedentary older adults. ## How did urolithin A get from a gut finding to a capsule? Ryu and colleagues reported in 2016 that urolithin A induced mitophagy in cells and in animals after oral dosing. Mitophagy is the process that the [2022 muscle trial](https://doi.org/10.1016/j.xcrm.2022.100633) describes as the recycling of faulty mitochondria. In the worm *C. elegans*, urolithin A extended lifespan. In two mouse models and in young rats, it improved exercise capacity ([Ryu et al., 2016](https://doi.org/10.1038/nm.4132)). Those results came from worms and rodents, not people. The first human study followed three years later, and it was built to test safety ([Andreux et al., 2019](https://doi.org/10.1038/s42255-019-0073-4)). All six urolithin A trial and mechanism papers cited in this post list at least one author with an Amazentis SA affiliation. The 2022 muscle trial calls the ingredient Mitopure. Read the trial record with that in mind. For the compound itself, see the [urolithin A monograph](/ingredients/urolithin-a), and the [urolithin A complete guide](/health/urolithin-a-complete-guide) covers the wider topic. Fruit-tree cultivation in the Levant dates to about 7,000 years ago. A 2025 study of 42 distance runners did not find a faster 3,000-meter time with urolithin A. ## Next reads - [Ellagic acid](/ingredients/ellagic-acid) is the parent compound that gut bacteria start from. - [The urolithin A complete guide](/health/urolithin-a-complete-guide) is the topic pillar, with the wider context for this history. ### Related reading - [Prebiotics history: fiber, bacteria and the 2017 definition](/blog/history/history-of-prebiotics-from-chicory-to-fiber-science) - [Resveratrol history: hellebore, knotweed and the French paradox](/blog/history/history-of-resveratrol-from-hellebore-to-french-paradox)