Urolithin A: The Postbiotic Your Microbiome Makes — If You Feed It Right

Most people know that antioxidants from berries, pomegranates, nuts, and colorful plants are good for us. But what almost no one realizes is this:

Some of the most powerful benefits from these foods don’t come from the foods themselves — they come from what your gut microbiome turns them into.

One of the most important of these compounds is urolithin A, a postbiotic that has exploded in scientific interest for its effects on:

• mitochondrial health

• mitophagy (cellular cleanup of damaged mitochondria)

• muscle strength and endurance

• immune system resilience

• healthy aging and longevity

What’s fascinating is that your body does not make urolithin A on its own — your gut microbes must create it. But here’s the twist:

Only 30–40% of people naturally make meaningful amounts of urolithin A, even when they eat all the right foods.

This makes urolithin A one of the clearest examples of why gut health is foundational to longevity — and one of the best-studied postbiotics in human trials today.

Let’s break it down.

What Is Urolithin A?

Urolithin A is a postbiotic, meaning it’s produced after digestion by the microbiome.

When you eat foods rich in ellagitannins (a type of polyphenol), they are broken down into ellagic acid — and then transformed by specific gut bacteria into urolithin A.

Urolithin A isn’t just another antioxidant. It has a unique, well-documented ability to:

• activate mitophagy (selective cleanup of damaged mitochondria)

• improve mitochondrial efficiency

• support muscle function and endurance in aging adults

• enhance immune resilience

• support metabolic health

This makes UA one of the most promising “cellular rejuvenation” compounds in modern longevity research.

How Does the Body Make Urolithin A?

The process relies entirely on the gut:

1. You eat ellagitannin-rich foods.

2. Your stomach and small intestine convert them to ellagic acid.

3. In the colon, specific bacteria transform ellagic acid into urolithin A.

4. UA is absorbed and used throughout the body.

This is why two people can eat the same foods and experience totally different benefits — it depends on whether they have the microbes required to make UA.

Foods That Support Natural Urolithin A Formation

Here are the best dietary sources of ellagitannins:

• Pomegranates (especially juice and arils)

• Walnuts

• Pecans

• Strawberries

• Blackberries

• Raspberries

These foods do not contain urolithin A — they contain its precursors.

Eating them regularly can improve UA production if the right gut bacteria are present.

Why Some People Don’t Make Urolithin A

People naturally fall into three “urolithin metabotypes,” based on how their gut responds to ellagitannins:

• UM-A: strong urolithin A producers

• UM-B: weak or mixed producers

• UM-0: non-producers

Only about one-third of the population falls into the high-producing category.

Reasons for low production include:

• missing key bacteria (genetically determined microbiome makeup)

• poor metabolic health

• history of antibiotics

• low microbiome diversity

• chronic gut inflammation or dysbiosis

• low-fiber, low-polyphenol diets

• aging

This is why you can give some people pomegranates all day long and their body still produces little to no UA.

Can You Test Your Urolithin A Status?

Testing is emerging but not yet part of routine clinical panels.

Researchers use urine or blood tests after a “pomegranate challenge” to classify someone into UM-A, UM-B, or UM-0.

Some specialty longevity programs offer this testing, but most clinicians do not yet have access to standardized assays.

For now, you generally “know” your status by:

• consuming ellagitannin-rich foods for several weeks

• evaluating how you respond (energy, endurance, muscle recovery, gut tolerance)

• or using commercial programs that test for UA metabolites

This will likely become more commonplace as personalized nutrition evolves.

Does Supplementing With Urolithin A Help You Become a Producer?

This is an important myth to clear up:

Supplementing with urolithin A does NOT train the microbiome to produce more of it.

UA supplements give you the finished product, bypassing gut metabolism.

They do not:

• increase your UA-producing bacterial strains

• change your urolithin metabotype

• convert non-producers into producers

It’s downstream — not a probiotic and not a microbiome trainer.

However, supplementation does allow everyone — even non-producers — to access the benefits.

Can You Train a Low-Producing Microbiome to Become a Better Producer?

For some people, yes — but only if the necessary bacteria are present at low levels.

Ways to improve natural UA production include:

1. Repeated intake of ellagitannin-rich foods

This can stimulate low-abundance bacteria if they exist.

2. Supporting SCFA (short-chain fatty acid) production

This improves microbial diversity and colonic health.

Key strategies:

• soluble fiber

• resistant starches

• pomegranate extract

• GOS, acacia fiber, psyllium

• berries & polyphenol diversity

3. Reducing gut inflammation

Because UA-producing bacteria are highly sensitive to inflammatory environments.

Supportive tools include:

• glutamine

• NAC

• cysteine-rich foods

• omega-3s

• butyrate

• demulcent herbs

• low seed-oil diet

4. Improving overall microbiome diversity

“Eat the rainbow” works here.

5. Maintaining metabolic health

Insulin resistance and dysbiosis often coexist.

Important note:

If someone is a true UM-0 non-producer, current research suggests that diet alone will not create the missing bacteria.
This may change in the future once targeted probiotics containing specific UA-producing strains become available.

Why Supplement Urolithin A? (Especially for Non-Producers)

Even with a perfect diet, the microbiome bottleneck means many people will never make enough UA on their own.

This is why supplementation has become so widely studied.

Clinical trials in older adults show that urolithin A supplementation:

• improves mitochondrial efficiency

• boosts mitophagy

• increases muscle endurance and strength

• improves mitochondrial biomarkers

• may support immune function

• reduces markers of inflammation

• supports healthy aging at the cellular level

These benefits occur even in people who naturally produce no UA.

This makes supplementation one of the most reliable ways to access the mitochondrial and longevity benefits.

Why Longevity Researchers Are So Excited About Urolithin A

UA hits every major theme in modern longevity science:

1. A natural mitophagy activator

Healthy aging depends on the continuous cleanup and renewal of mitochondria.
UA is one of the few compounds proven to do this in animals and suggested by biomarkers in humans.

2. Cross-species evidence

• Worms: extended lifespan

• Rodents: improved muscle function and endurance

• Humans: improved muscle endurance, strength, mitochondrial biomarkers

This is extremely rare in nutrition science.

3. It’s a postbiotic

It beautifully illustrates the diet → microbiome → mitochondria → longevity pathway.

4. It’s accessible

It comes from real food.
And supplementation allows even non-producers to benefit.

5. It has a clean safety profile in studies

Human trials show strong tolerability.

Altogether, urolithin A presents one of the clearest, most evidence-backed ways to support cellular energy, muscle health, and healthy aging.

How to Support Urolithin A Naturally

Whether or not you supplement, these strategies boost cellular and gut health:

Eat ellagitannin-rich foods

• pomegranates

• berries

• walnuts

Support your gut microbiome

• diversity of plants

• resistant starches

• polyphenol-rich diet

• low seed-oil, anti-inflammatory approach

• fermented foods if tolerated

Improve metabolic and mitochondrial health

• daily walking

• strength training

• quality sleep

• stress regulation

• sunlight exposure

These behaviors amplify the effects of UA and support your body’s natural longevity pathways.

Final Takeaway

Urolithin A might be one of the clearest examples of how your gut microbiome shapes your longevity.

Some people produce it naturally.
Many do not.
And even among producers, the levels vary wildly.

But the science is clear:

• Urolithin A improves mitochondrial function

• It supports muscle strength and endurance

• It enhances cellular cleanup (mitophagy)

• It may benefit immune and metabolic health

• It plays a role in healthy aging

• And supplementation provides consistent levels for everyone

If you want to optimize your mitochondrial health, support graceful aging, or build a more resilient gut–brain–body system, urolithin A is one of the most exciting tools we currently have in the modern longevity toolbox.

Want professional-grade supplements that support gut, mitochondrial, and longevity health?
👉 Explore my recommended formulas through my Fullscript dispensary:
https://us.fullscript.com/welcome/pharmtofunction