Ca-AKG vs Urolithin A: human evidence and mechanisms compared

Ca-AKG and Urolithin A target different aging-related biology, and their human evidence differs in an important way. Urolithin A has more direct randomized human muscle and mitochondrial data. Ca-AKG has broader metabolic and epigenetic biology, but its most prominent modern human aging signal remains observational.

Neither compound has shown that it extends human lifespan or prevents age-related disease.

Ca-AKG vs Urolithin A at a glance

Question	Ca-AKG	Urolithin A
Core biology	TCA-cycle metabolite; AKG-dependent enzymes; nutrient, immune and senescence signaling	Gut-metabolite/postbiotic studied for mitophagy and mitochondrial quality control
Human target engagement	Oral metabolic activity; aging-pathway engagement less directly characterized	Plasma exposure plus muscle mitochondrial/mitophagy biomarker changes
Randomized human efficacy	Bone RCT; aging RCT outcomes not yet published	Several short RCTs in muscle/physical-performance settings
Human longevity evidence	None	None
Main evidence limitation	Small aging evidence base; observational biological-age signal; mixed mouse lifespan replication	Small, short trials; heterogeneous outcomes; substantial industry involvement

What is Urolithin A?

Urolithin A is a metabolite that some gut microbiomes produce from ellagitannins and ellagic acid found in foods such as pomegranates, walnuts and berries.

Because natural production varies between individuals, supplemental Urolithin A provides the metabolite directly rather than relying on the gut microbiome to generate it.

Its headline mechanism is mitophagy—the selective recycling of damaged mitochondria.

Does Urolithin A reach humans and change mitochondrial biology?

Yes, there is direct human target-engagement evidence.

A 2019 first-in-human study found oral Urolithin A bioavailable and generally well tolerated, with changes in plasma acylcarnitines and skeletal-muscle mitochondrial gene expression after repeated dosing [1].

A 2022 randomized trial in middle-aged adults found dose-dependent changes in muscle proteins related to mitophagy and oxidative phosphorylation [2].

That gives Urolithin A a stronger direct human mitochondrial target-engagement story than Ca-AKG currently has.

Did the 2022 Urolithin A trial meet its primary endpoint?

No.

The ATLAS trial's prespecified primary endpoint—peak power output—did not improve significantly versus placebo [2].

There were positive secondary findings. Hamstring peak torque improved significantly at both tested doses, and the 1,000 mg group showed favorable within-group changes in peak VO2 and six-minute walk distance. Mitochondrial and inflammatory biomarkers also changed.

Those findings are worth reporting. The primary-endpoint miss is equally important.

What did the 2025 runner trial show?

A 2025 randomized study in highly trained male distance runners found no significant improvement in the 3,000 m time trial with Urolithin A [3].

It did report lower perceived exertion, lower post-exercise creatine-kinase exposure and mitochondrial/inflammatory proteomic changes.

Again, the pattern is consistent: biologic and recovery signals are easier to demonstrate than a reproducible performance benefit.

What does the 2026 systematic review say?

A 2026 systematic review and meta-analysis included five randomized Urolithin A trials with 236 participants. Quantitative pooling was possible only for the six-minute walk test.

The pooled estimate favored Urolithin A by about 17 metres, but the confidence interval crossed zero and the result was not statistically significant. The certainty of evidence was rated low. Other strength, endurance and mitochondrial outcomes were too heterogeneous for reliable quantitative pooling.

See the 2026 Urolithin A muscle-health systematic review and meta-analysis [10].

That is a useful counterweight to reading individual positive secondary endpoints in isolation.

What is Ca-AKG's strongest human evidence?

Ca-AKG has a different evidence pattern.

The 2007 osteopenia RCT found a significant reduction in the bone-resorption marker CTX versus calcium alone [4].

For aging specifically, the strongest modern signal comes from delayed-release Rejuvant observational data. In the 2026 cohort, delayed-release users had a lower cross-sectional DNA-methylation Age Residual, while the adjusted longitudinal signal was not significant [5].

ABLE is the key randomized aging trial, but its audited publications are the protocol and recruitment analysis rather than efficacy results [6].

What about Ca-AKG's mouse lifespan evidence?

The 2020 Shahmirzadi study reported significant female lifespan extension and lower frailty burden in C57BL/6 mice [7].

Two later NIA Interventions Testing Program experiments in genetically heterogeneous UM-HET3 mice did not reproduce lifespan extension [8] [9].

So the Ca-AKG preclinical lifespan story is mixed rather than uniformly positive.

Which has stronger evidence for muscle?

Urolithin A has the more direct human muscle evidence.

It has randomized trials measuring muscle strength, endurance, physical performance and muscle-biopsy mitochondrial markers. The results are mixed and the pooled evidence remains low certainty, but they are direct human outcomes.

Ca-AKG's muscle/frailty evidence is primarily mouse and mechanistic, with no completed Ca-AKG sarcopenia trial in humans.

See Ca-AKG and muscle/frailty.

Which has stronger evidence for “biological age”?

Ca-AKG has the more direct published DNA-methylation-age association because that endpoint was measured in the Rejuvant studies.

That does not make Ca-AKG the more clinically proven anti-aging supplement. The association is observational and formulation-specific, and it has not yet been confirmed in a completed randomized Ca-AKG aging trial.

Urolithin A's human program is centered more on mitochondrial biomarkers and muscle function than on epigenetic clocks.

How independent is the evidence?

This is an important limitation for Urolithin A.

The 2019 safety/biomarker study and the 2022 ATLAS trial were company-run and predominantly authored by employees of Amazentis, which manufactures Urolithin A as Mitopure [1] [2].

The 2025 runner study had university-affiliated lead investigators, but commercial co-authors from Amazentis/Nestlé Health Science remained involved [3].

Ca-AKG is not free from commercial entanglement either: the Shahmirzadi and Rejuvant programs have disclosed Ponce de Leon Health/Gerostate relationships. Independent replication matters for both ingredients.

Can Ca-AKG and Urolithin A be taken together?

No published human trial has shown that the combination improves mitochondrial health, muscle function, biological age or another longevity outcome more than either ingredient alone.

The mechanisms are distinct enough to make combination research plausible. That is not evidence of synergy.

See Ca-AKG stacking.

Which one is “better”?

There is no universal evidence-based winner.

For direct human mitochondrial and muscle target engagement, Urolithin A currently has the more developed evidence base, although efficacy outcomes are inconsistent and the 2026 pooled six-minute-walk result was inconclusive.

For DNA-methylation-age association, delayed-release Ca-AKG has the more direct published signal, but it remains observational.

For human lifespan or prevention of age-related disease, neither has demonstrated efficacy.

Bottom line

Urolithin A has the stronger direct human mitochondrial and muscle research program. Ca-AKG has broader aging biology, a randomized bone-marker result and an observational biological-age signal, but less direct human mitochondrial evidence.

The fairest 2026 comparison is not “which supplement wins?” It is:

• Urolithin A: more direct human mitochondrial/muscle target engagement, mixed functional outcomes, low-certainty pooled evidence and substantial industry involvement.
• Ca-AKG: broader mechanistic aging case, observational biological-age data, a mixed mouse lifespan record and randomized aging outcomes still unavailable.

Neither has proven human longevity efficacy.