What Is Urolithin A? A Complete, Science-Backed Guide

What is Urolithin A, exactly?

Urolithin A is a small molecule produced in the gut when resident bacteria metabolize a class of dietary polyphenols called ellagitannins and their breakdown product, ellagic acid. Because it is generated by the microbiome rather than eaten directly, scientists classify it as a postbiotic: a beneficial compound that results from bacterial activity in the digestive tract. A review in Molecular Biology Reports traces Urolithin A's journey from dietary ellagitannins to clinical use (Molecular Biology Reports, 2026).

The key thing to understand is that the pomegranate or handful of walnuts you eat does not contain Urolithin A. It contains the raw materials. Your gut microbes do the manufacturing, and only if you host the right ones.

How the body makes Urolithin A

The pathway runs in stages. Ellagitannins are large molecules that are poorly absorbed, so most of them travel to the colon. Along the way they are hydrolyzed to release ellagic acid. Specific gut bacteria then open its ring structure and strip away hydroxyl groups step by step, producing intermediate urolithins (such as urolithin C) and finally Urolithin A, which is absorbed and circulates mostly in a conjugated (glucuronide) form. This multi-step microbial biosynthesis is reviewed in Food Science and Biotechnology (2026), and a systematic review of in vivo studies catalogs how these metabolites behave once formed (Nutrients, 2022).

Foods that supply the raw material

You can't eat Urolithin A, but you can eat its precursors. The richest dietary sources of ellagitannins include:

Food source	Precursor supplied	Notes
Pomegranate (juice, arils)	Punicalagins, ellagic acid	Among the most concentrated dietary sources of ellagitannins
Walnuts	Ellagitannins	A leading nut source of ellagic acid precursors
Raspberries	Ellagitannins	Berries are a notable everyday source
Strawberries	Ellagitannins	Contributes ellagic acid to the diet
Blackberries	Ellagitannins	Similar berry-family profile
Pecans & chestnuts	Ellagitannins	Additional nut sources

For portion ideas and how much of each food it takes to supply meaningful precursors, see our guide to getting Urolithin A from food.

Why can't most people make enough Urolithin A?

This is the central catch. Producing Urolithin A efficiently depends on hosting particular gut bacteria, and not everyone does. Researchers sort people into urolithin metabotypes based on what their microbiome produces from ellagitannins: metabotype A makes mainly Urolithin A, metabotype B makes Urolithin A plus isourolithin A and urolithin B, and metabotype 0 makes little or none (Tomás-Barberán et al., Molecular Nutrition & Food Research, 2017).

The practical upshot is that the amount of Urolithin A people make from the same food varies enormously, and a substantial share of people produce little or none no matter how many pomegranates or walnuts they eat. Estimates of how many people are efficient producers vary between studies and populations, and converter status can shift with age, diet, and the overall makeup of the microbiome. Our explainer on converter status goes deeper.

Why direct supplementation sidesteps the problem

Because converter status is so variable, researchers tested whether taking Urolithin A directly could bypass the microbiome lottery. A human study in the European Journal of Clinical Nutrition found that direct supplementation delivered consistent Urolithin A levels across participants regardless of their gut-bacteria makeup or diet, while levels from pomegranate juice varied widely from person to person (European Journal of Clinical Nutrition, 2022). In other words, a supplement gives non-converters access to the same compound that efficient producers make on their own.

How does Urolithin A work in the body?

Urolithin A's headline mechanism is mitophagy, a quality-control process in which cells identify aging, dysfunctional mitochondria, wrap them in a membrane, and break them down for parts, making room for healthy new ones. Mitochondria are the energy generators inside your cells, and a decline in their quality is one of the recognized hallmarks of aging. By supporting the clearance of damaged mitochondria, Urolithin A is studied for its role in helping cells keep a fitter, more efficient energy supply. For a plain-language walkthrough, see what mitophagy is and why it declines with age.

Preclinical (animal and cell research): the mitophagy effect was first described in worms, rodents, and cell models, where Urolithin A induced mitophagy and improved muscle function in aged animals (Ryu et al., Nature Medicine, 2016). Human research: the first-in-human trial then reported that Urolithin A was safe and well tolerated in older adults and shifted skeletal-muscle mitochondrial gene expression and plasma acylcarnitines at 500 mg and 1,000 mg over four weeks (Andreux et al., Nature Metabolism, 2019). That showed the mitochondrial signature seen in animals also appears in human muscle.

What does the human research say Urolithin A supports?

A 2024 systematic review in Ageing Research Reviews pooled the human trials at the time (five studies, about 250 healthy people). It found muscle strength and endurance gains, an anti-inflammatory effect, and upregulated mitochondrial and autophagy genes, but no effect on body composition, gait speed, or mitochondrial ATP production (Hodzic Kuerec et al., Ageing Research Reviews, 2024). Here are the best-studied areas.

Muscle strength and endurance

• Older adults: in a randomized trial in JAMA Network Open, the primary outcome (6-minute walk distance) did not improve significantly versus placebo, but hand and leg muscle endurance did, and plasma markers including acylcarnitines and C-reactive protein fell (Liu et al., 2022).
• Middle-aged adults: four months of 500 mg or 1,000 mg daily improved leg muscle strength compared with placebo, alongside favorable mitochondrial biomarkers (Singh et al., Cell Reports Medicine, 2022).
• Resistance-trained men: a small 8-week trial (20 men, 1,000 mg daily) reported greater gains in strength and repetitions to failure and lower C-reactive protein than placebo (Zhao et al., Journal of the International Society of Sports Nutrition, 2024).
• Trained distance runners: in 42 competitive runners at an altitude camp, 4 weeks of 1,000 mg daily did not improve 3,000 m time-trial performance, but lowered perceived exertion and a blood marker of post-exercise muscle damage (Whitfield et al., Sports Medicine, 2025).

Latest evidence check: a 2026 systematic review and meta-analysis of five randomized trials (236 participants) concluded that the muscle findings are promising but heterogeneous, with too few, too small, and too short trials to draw firm conclusions. Pooled 6-minute walk results did not reach statistical significance (Dao et al., Frontiers in Nutrition, 2026). That is the honest state of play: consistent signals for muscle endurance and mitochondrial markers, and a clear need for larger studies.

Cellular energy

Because Urolithin A supports mitophagy and mitochondrial renewal, mitochondrial markers are a recurring theme across trials. The Nature Metabolism study documented gene-expression shifts consistent with improved mitochondrial function, and later trials tracked biomarkers such as acylcarnitines, which tend to build up when mitochondria burn fat less efficiently. Note that these are lab markers; the 2024 review found no direct change in mitochondrial ATP production, so "more energy" in the everyday sense has not been shown.

Healthy aging and the immune system ("inflammaging")

One of the most notable recent findings comes from a randomized, placebo-controlled trial in Nature Aging. In 50 healthy adults aged 45 to 70, taking 1,000 mg of Urolithin A daily for four weeks expanded naive-like, less exhausted CD8+ T cells, increased their capacity to burn fatty acids, and raised markers of mitochondrial biogenesis in those cells (Denk et al., Nature Aging, 2025). These are features associated with a younger immune profile. The study measured immune-cell biomarkers, not real-world outcomes such as how often people get sick, so it supports a role in healthy immune aging rather than proving one.

How do people supplement Urolithin A, and what doses are studied?

Since most people can't manufacture predictable amounts on their own, supplementation with standardized Urolithin A has become the practical route. Human trials have concentrated on two daily doses:

Studied daily dose	Example research context	Duration studied
500 mg	Mitochondrial biomarkers in older adults; muscle strength in middle-aged adults	4 weeks to 4 months
1,000 mg	Muscle endurance and strength; resistance-trained men; immune and mitochondrial markers in adults 45 to 70	4 weeks to 4 months

The 1,000 mg dose is the higher of the two levels evaluated in controlled trials. SOMA Urolithin A gummies deliver 1,000 mg per 4-gummy daily serving, giving both non-converters and efficient producers a consistent daily amount without depending on diet or gut bacteria. Our Urolithin A dosage guide covers how to choose between 500 mg and 1,000 mg and when to take it.

Food vs. supplement: which makes sense?

Eating ellagitannin-rich foods like pomegranates, walnuts, and berries is worthwhile in its own right: they deliver the precursors plus fiber and other polyphenols. But for people who aren't efficient converters, food alone won't reliably produce Urolithin A, and even for converters the amount varies day to day. A supplement provides the finished compound directly, which is why it produces consistent levels across people (European Journal of Clinical Nutrition, 2022). Think of it as complementary: keep the whole foods, and add a standardized dose if you want a predictable amount.

Is Urolithin A safe and well tolerated?

Across the clinical trials conducted to date, Urolithin A has been reported as safe and well tolerated at the studied doses. The first-in-human study specifically evaluated safety and found a favorable profile (Nature Metabolism, 2019), and the 2024 systematic review reported no serious Urolithin A-related side effects across trials of up to four months (Ageing Research Reviews, 2024). Long-term data beyond a few months are still limited.

Talk with your doctor before starting if you are pregnant or nursing, take prescription medications, or are managing a health condition. Supplements are meant to support general wellness, not to replace medical care.

Frequently asked questions

Is Urolithin A the same as a probiotic?

No. A probiotic is a live bacterium; Urolithin A is a postbiotic, a compound that gut bacteria produce when they metabolize dietary ellagitannins. You take the end product directly rather than the microbes that make it.

Can I just eat pomegranates and walnuts instead?

You can, and those foods supply the precursors. But conversion depends on your gut bacteria, and many people produce little Urolithin A from food alone. A standardized supplement delivers the finished compound regardless of converter status.

What is mitophagy in simple terms?

Mitophagy is your cells' recycling program for mitochondria, the tiny power plants that make energy. When mitochondria get old or damaged, mitophagy clears them out so healthier ones can take over. Urolithin A is studied for its ability to support this process.

How much Urolithin A do studies use?

Human clinical trials have primarily used 500 mg or 1,000 mg per day, over durations ranging from four weeks to four months.

How long until Urolithin A may show effects?

Trials measured biomarker changes at about four weeks and muscle-strength outcomes at two to four months. Individual responses vary, and the studies were designed around consistent daily use.

Is the research settled?

Not yet. The human trials are consistent in direction for muscle endurance and mitochondrial markers, but they are small and short. Larger, longer trials are needed, and we will update this guide as they are published.