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Supplements · §557
Urolithin A
Your gut bacteria make urolithin A from pomegranate and walnuts, but a tenth to more than half of Western adults make none, with no test to tell you which you are. The pill skips that lottery. Five trials in people over 40 nudged muscle endurance, heart-disease markers, and the immune signature of aging the right way. The effects are modest, it costs about a thousand a year, and the maker wrote most of the studies. Worth it once the cheaper basics are locked in.
Do · Daily Evidence Emerging Chapter Supplements

What it does: your cells' tiny power plants, mitochondria, break down with age, and the crew that recycles the broken ones gets sluggish by 60. Urolithin A turns that recycling back up 1. Because it's made by gut bacteria not everyone hosts, eating the food does nothing for the roughly half of readers who can't convert it 2. The supplement produces the same blood levels either way 3.

The strongest signal is immune. Four weeks at 1,000 mg shifted the aging-prone CD8+ T cells back toward a younger profile 4. Behind it: hamstring strength up about 12% over placebo in middle-aged adults 5, leg endurance up about 17% in older adults 6, and heart-disease blood markers moving the right way 7.

Read the asterisks. Two muscle trials missed their pre-specified main outcome and hit on the secondary ones. The one trial without maker-affiliated authors, in trained runners, found no speed gain but easier recovery 8. Pooling all five, it didn't raise peak mitochondrial energy output or mitochondrial count 9. It recycles broken engines; it doesn't build more.

If you decide yes, here's the routine.

Buy these first. Resistance training twice a week moves the same muscle and immune targets, free. Creatine monohydrate costs about $30 a year with decades of evidence. Protein around 1.6 g per kg of body weight a day is the strongest diet lever against age-related muscle loss. Urolithin A is what you add once those are handled; before that, you're paying a thousand a year for the smallest move in the stack.

The arc, if you take it.

  • Weeks 1–4: nothing felt; inflammation and immune-cell markers start to shift on paper 4.
  • Weeks 8–12: leg endurance begins to budge, so you're less gassed at the top of the stairs 6.
  • Months 4+: strength up ~12%, bike VO₂ up ~10%, on top of your training 5.
  • Years: unmeasured. The longest trial is four months, so a decade is a bet on the mechanism, not the endpoint.
The fine print — when to skip it, and what people get wrong

Skip if pregnant or breastfeeding (no data), and ask your oncologist first during active cancer treatment. No trial data under 40. Otherwise the safety record across the trials is clean, and it has GRAS status 10.

"Just eat more pomegranate" fails for the readers whose gut can't convert it 3. "It boosts cellular energy" overstates the trials: it recycles damaged mitochondria, it doesn't raise energy output 9.

References
  1. 1Ryu D, Mouchiroud L, Andreux PA, et al. (2016). Urolithin A induces mitophagy and prolongs lifespan in C. elegans and increases muscle function in rodents. Nature Medicine. link
  2. 2Tomás-Barberán FA, González-Sarrías A, García-Villalba R, et al. (2017). Urolithins, the rescue of "old" metabolites to understand a "new" concept: metabotypes as a nexus among phenolic metabolism, microbiota dysbiosis, and host health status. Molecular Nutrition & Food Research. link
  3. 3D'Amico D, Andreux PA, Valdés P, et al. (2021). Direct supplementation with urolithin A overcomes limitations of dietary exposure and gut microbiome variability in healthy adults to achieve consistent levels across the population. European Journal of Clinical Nutrition. link
  4. 4Denk D, Petrocelli JJ, Singh A, et al. (2025). Effect of the mitophagy inducer urolithin A on age-related immune decline: a randomized, placebo-controlled trial. Nature Aging. link
  5. 5Singh A, D'Amico D, Andreux PA, et al. (2022). Urolithin A improves muscle strength, exercise performance, and biomarkers of mitochondrial health in a randomized trial in middle-aged adults. Cell Reports Medicine. link
  6. 6Liu S, D'Amico D, Shankland E, et al. (2022). Effect of urolithin A supplementation on muscle endurance and mitochondrial health in older adults: a randomized clinical trial. JAMA Network Open. link
  7. 7Singh A, D'Amico D, Marcinek DJ, et al. (2025). Urolithin A provides cardioprotection and mitochondrial quality enhancement preclinically and improves human cardiovascular health biomarkers. iScience. link
  8. 8Petrocelli JJ, D'Amico D, Singh A, et al. (2025). Evaluating the impact of urolithin A supplementation on running performance, recovery, and mitochondrial biomarkers in highly trained male distance runners. Sports Medicine. link
  9. 9Hodzic Kuerec A, Lim XK, Khoo AL, et al. (2024). Targeting aging with urolithin A in humans: a systematic review. Ageing Research Reviews. link
  10. 10FDA (2018). GRAS Notice 791: Urolithin A — agency response letter. link
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