Urolithin A and C15:0: Mitochondrial Renewal for Healthy Ageing

TL;DR: Urolithin A and pentadecanoic acid (C15:0) are two of the most discussed next-generation longevity supplements. Urolithin A has the stronger human evidence base: several randomised trials show it activates mitophagy and improves mitochondrial biomarkers in muscle and immune cells. C15:0 has compelling cell-system and observational data but fewer clinical trials. Neither has been proven to extend human lifespan.

1. Why Mitochondria Matter for Ageing

Mitochondria produce the ATP that powers almost everything a cell does. With age, mitochondria become damaged, less efficient and less able to be recycled. This contributes to:

• Muscle weakness and reduced exercise capacity
• Chronic low-grade inflammation
• Declining immune function
• Impaired metabolic health
• Increased oxidative stress

Compounds that restore mitochondrial quality are therefore attractive geroprotectors. The two main approaches are mitophagy inducers (clear out damaged mitochondria) and membrane stabilisers (protect what remains).

2. Urolithin A: The Mitophagy Activator

Urolithin A is a gut-microbiome metabolite formed from ellagitannins in pomegranates, walnuts, strawberries and some berries. It activates mitophagy through the PINK1/Parkin pathway and related quality-control systems.

Human evidence

• 2022 JAMA Network Open trial: a randomised, double-blind, placebo-controlled study in older adults found that 1,000 mg/day Urolithin A improved muscle endurance and mitochondrial health biomarkers compared with placebo (Andreux et al., 2022).
• 2025 Nature Aging trial: Urolithin A improved markers of age-related immune decline in a randomised placebo-controlled trial, supporting the idea that mitochondrial quality matters for immune ageing (Singh et al., 2025).
• Cardiovascular biomarkers: a 2025 iScience study reported that Urolithin A improved cardiovascular biomarkers and mitochondrial quality in preclinical models and in a human cohort (Liu et al., 2025).
• Systematic review: a 2025 medRxiv preprint reviewed human trials of Urolithin A on muscle strength, mass and physical performance, noting benefits in mitochondrial markers but mixed effects on functional endpoints (Watts et al., 2025).

Food vs supplement

Most people do not produce high levels of Urolithin A from food because it depends on the gut microbiome. Commercial supplements use synthetic Urolithin A, typically at 500–1,000 mg/day, which is closer to study doses than dietary intake.

3. C15:0 (Pentadecanoic Acid): The Membrane Stabiliser

C15:0 is an odd-chain saturated fatty acid found in dairy fat, some fish and fortified foods. Researchers have proposed it as an "essential" fatty acid because low plasma levels correlate with higher risks of metabolic syndrome, cardiovascular disease and type 2 diabetes.

What the research says

• Cell-system comparison: a 2022 PLOS ONE study tested C15:0 across 12 primary human cell-based disease systems and reported broader and safer activity profiles than omega-3 fatty acids in those models (Venn-Watson et al., 2022).
• Longevity compound overlap: a 2023 Nutrients paper reported that C15:0 shares clinically relevant cell-based activities with leading longevity-enhancing compounds such as rapamycin, metformin and resveratrol (Venn-Watson & Watson, 2023).
• Randomised trial: a 2024 Journal of Nutrition RCT in young adults with overweight and obesity found C15:0 supplementation was safe and favourably altered some metabolic markers (Robinson et al., 2024).
• Observational caution: a 2026 Frontiers in Nutrition analysis of CARDIA and ARIC cohorts found only modest associations between plasma C15:0 and cardiovascular health, with no clear evidence of causality (Harris et al., 2026).

Unlike Urolithin A, C15:0 has no large human trial showing improved muscle, immune or mitochondrial function. The evidence is promising but earlier-stage.

4. How They Might Work Together

Urolithin A and C15:0 target different parts of the mitochondrial problem:

• Urolithin A triggers quality control: it tags and removes damaged mitochondria so the cell can build fresh ones.
• C15:0 may stabilise cell membranes, including mitochondrial membranes, and support metabolic signalling pathways.

Whether combining them produces additive benefits is unknown. No published human trial has tested them together.

5. Dosing, Safety and UK Availability

Urolithin A

• Study doses: typically 500–1,000 mg/day of pure Urolithin A.
• Products sold as "Mitopure" or generic Urolithin A are available in the UK as food supplements.
• Side effects are generally mild (GI upset in some trials). Long-term safety beyond a few months is not well characterised.

C15:0

• Study doses: typically 100–200 mg/day of pentadecanoic acid.
• Sold as "Fatty15" or generic C15:0 supplements.
• Derived from a saturated fat; people with dairy allergies should check the source. Those with lipid disorders should speak to a clinician.

6. References

7. FAQ