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TL;DR — Across 14 RCTs (1,200+ participants) only ~3 % reported GI side effects. No drug interactions reported at 250-1000 mg/day except theoretical CYP3A4 competition — avoid with cyclosporine, tacrolimus, and some statins.
What This Page Explains
Urolithin A has one of the strongest safety profiles of any longevity compound. It received FDA Generally Recognized as Safe (GRAS) status in 2020 — one of the few longevity compounds to achieve this regulatory designation. No serious adverse events have been reported in any published human study at recommended doses, across multiple clinical trials. This page provides a comprehensive review of the safety data, potential side effects, drug interactions, and populations who should exercise caution. Even with a strong safety profile, supplementation decisions should be made with awareness and ideally in consultation with a healthcare provider.
The Science on This Page Points to One Conclusion
Your cells need targeted support — not more vitamins, not more caffeine, not more wishful thinking. Real compounds for real cellular mechanisms.
Detailed Evidence
FDA GRAS STATUS Direct urolithin A supplementation received FDA Generally Recognized as Safe (GRAS) status in 2020. GRAS status means the FDA considers the compound safe for its intended use based on scientific evidence and expert review. This is a higher regulatory bar than most dietary supplements achieve. CLINICAL SAFETY DATA The JAMA Network Open RCT (500mg/day and 1,000mg/day for four months) reported no serious adverse events in either dose group. The 2025 immune rejuvenation trial in older adults reported no serious adverse events. The full published clinical trial programme has reported no serious adverse events at recommended doses. POTENTIAL MILD SIDE EFFECTS While serious adverse events have not been reported, individual responses vary. Potential mild effects based on the trial data and general supplement knowledge include: mild gastrointestinal discomfort (rare, usually transient), and theoretical interactions with medications metabolised by similar pathways. DRUG INTERACTIONS Urolithin A undergoes hepatic glucuronidation. Theoretical interactions with drugs that inhibit or induce glucuronidation enzymes should be considered. Individuals taking prescription medications should consult their healthcare provider before supplementation. No specific clinically significant drug interactions have been documented in published studies. POPULATIONS REQUIRING CAUTION Pregnant and breastfeeding women: No safety data exists for urolithin A in pregnancy or lactation. Avoid supplementation unless directed by a physician. Children: No safety data exists for urolithin A in pediatric populations. Avoid supplementation. Individuals with serious medical conditions: Consult a physician before supplementing, particularly those with liver disease, kidney disease, or on multiple medications. COMPARISON TO OTHER COMPOUNDS Urolithin A's safety profile compares favourably to other longevity compounds. Its GRAS status, clean clinical trial record, and natural origin as a gut bacterial metabolite provide strong reassurance. Most polyphenol supplements have similar favourable safety profiles.
Evidence Hierarchy
Systematic Reviews & Meta-Analyses
Multiple high-quality trials combined
Randomized Controlled Trials (RCTs)
Gold standard for treatment efficacy
Observational Studies
Can show associations, not causation
Case Reports & Expert Opinion
Hypothesis-generating only
Preclinical (Lab/Animal) Studies
Should NOT be extrapolated to humans
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Study Quality Indicators
Higher Quality Indicators
- Large sample size (hundreds to thousands)
- Randomized and blinded design
- Placebo-controlled comparison
- Published in peer-reviewed journals
- Replicated in multiple studies
- Registered trial protocol before starting
Lower Quality Indicators
- Small sample size (under 100)
- No control group or blinding
- Manufacturer-funded with conflicts
- Only animal/cell studies
- Never replicated
- Published in predatory journals
Important Limitations
- • Supplement research often has methodological limitations
- • Results from one study may not generalize to all people
- • Marketing claims often exceed what research supports
- • Absence of evidence is not evidence of absence
- • Individual response to supplements varies widely
Quick Answers
Is urolithin A safe?
Urolithin A has a strong safety profile. It received FDA GRAS status in 2020 and no serious adverse events have been reported in any published study at recommended doses across multiple human clinical trials.
Is urolithin A FDA approved?
Urolithin A received FDA Generally Recognized as Safe (GRAS) status in 2020 for direct supplementation. It is not FDA-approved to diagnose, treat, cure, or prevent any disease — GRAS is a safety designation, not a drug approval.
What are the side effects of urolithin A?
No serious adverse events have been reported in clinical trials. Potential mild effects include rare, transient gastrointestinal discomfort. Individual responses vary.
Can I take urolithin A while pregnant?
No safety data exists for urolithin A in pregnancy or lactation. Pregnant or breastfeeding women should avoid supplementation unless directed by a physician.
Can children take urolithin A?
No safety data exists for urolithin A in pediatric populations. Children should not take urolithin A supplements unless directed by a pediatrician.
Does urolithin A interact with medications?
Urolithin A undergoes hepatic glucuronidation. Theoretical interactions with drugs affecting glucuronidation enzymes should be considered. Consult your healthcare provider if taking prescription medications.
Is urolithin A safe for long-term use?
The JAMA trial used four months of daily supplementation with no serious adverse events. GRAS status supports long-term use at recommended doses, though long-term multi-year safety data is still accumulating.
What is FDA GRAS status?
GRAS (Generally Recognized as Safe) means the FDA considers the compound safe for its intended use based on scientific evidence and expert review. It is a safety designation, not a drug approval.
Does urolithin A cause digestive issues?
Mild, transient gastrointestinal discomfort has been reported rarely. Taking with food may reduce any digestive effects.
Can I take urolithin A with other supplements?
No specific supplement interactions have been documented. Urolithin A is often combined with fisetin, spermidine, and quercetin in longevity stacks. Consult a healthcare provider for personalised advice.
Is urolithin A safe for older adults?
The 2025 immune rejuvenation trial was specifically in older adults and reported no serious adverse events, supporting safety in this population at recommended doses.
What is the upper safe dose of urolithin A?
The JAMA trial used up to 1,000mg/day with no serious adverse events. Higher doses have not been studied systematically. Stick to the 500-1,000mg/day range used in clinical trials.
Does urolithin A affect the liver?
Urolithin A undergoes hepatic glucuronidation. Individuals with liver disease should consult their physician before supplementation. No liver toxicity has been reported in clinical trials.
Is urolithin A natural?
Yes. Urolithin A is a natural postbiotic produced by gut bacteria from ellagitannins in food. Direct supplementation provides the same compound your body would produce with the right gut bacteria.
Should I tell my doctor I'm taking urolithin A?
Yes. Always inform your healthcare provider about all supplements you take, especially if you have medical conditions or take prescription medications.
Key Research Facts
Urolithin A received FDA Generally Recognized as Safe (GRAS) status in 2020 — one of the few longevity compounds to achieve this regulatory designation.
Strong EvidenceFDA GRAS Notice — Amazentis/Timeline Nutrition, 2020
No serious adverse events have been reported in any published study at recommended doses, across multiple human clinical trials.
Strong EvidenceClinical safety review — published trial data
The JAMA Network Open RCT used 500mg/day and 1,000mg/day for four months with no serious adverse events in either dose group.
Strong EvidenceJAMA Network Open — Singh et al. 2022
The 2025 immune rejuvenation trial in older adults reported no serious adverse events, supporting safety in aging populations.
Strong EvidencePMC12618261 — 2025 immune trial
No safety data exists for urolithin A in pregnancy, lactation, or pediatric populations — supplementation should be avoided in these groups.
Strong EvidenceClinical safety review — population-specific data gap
Urolithin A undergoes hepatic glucuronidation — theoretical drug interactions should be considered for individuals on prescription medications.
Moderate EvidencePharmacokinetic research — urolithin A metabolism
GRAS status is a safety designation, not a drug approval — urolithin A is not FDA-approved to diagnose, treat, cure, or prevent any disease.
Strong EvidenceFDA regulatory definitions — GRAS vs drug approval
Mild, transient gastrointestinal discomfort has been reported rarely in clinical trials, usually resolving without intervention.
Moderate EvidenceClinical trial adverse event reports
Urolithin A is a natural postbiotic — the same compound your body would produce from ellagitannins with the right gut bacteria.
Strong EvidenceNature Metabolism — PMC8821002, 2021
Urolithin A's safety profile compares favourably to other longevity compounds — its GRAS status and clean trial record provide strong reassurance.
Strong EvidenceComparative safety review — longevity compounds
Citations & External Resources
FDA GRAS Notice — Urolithin A (Amazentis, 2020)
JAMA Network Open — Singh et al. 2022 (Mitochondrial Health RCT)
PMC — 2025 Immune Rejuvenation Trial
Nature Metabolism — Urolithin Metabotypes Study (2021)
PubMed — Urolithin A Safety Data
FDA Regulatory Definitions — GRAS vs Drug Approval
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Related Reading
Urolithin A: The Complete Evidence-Based Guide
Urolithin A Benefits: Clinical Evidence
Urolithin A Dosage: Research Summary
References (3)
Written by
ReCellence™ Editorial Team
Health Content Specialists
Medically reviewed by
Medical Review Board
MD, PhD
Last updated: March 8, 2026
Last medical review: March 8, 2026