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Head-to-head evidence comparison — which supplement is right for you?
L-Citrulline vs Ornithine: L-Citrulline has the stronger overall evidence (6 vs 5/10); they're alternatives for improve endurance — the best pick depends on your goals. Take the 60-second quiz for a pick tailored to your goals.
L-Citrulline wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
3 of 4 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
4 of 4 studies with measurable effects showed benefit.
Top outcomes
3-6g (or 6-8g citrulline malate)
30-60 minutes before exercise, Or split doses throughout day
L-Citrulline powder (pure form)
2-6g daily
Before exercise for fatigue reduction, Before bed for sleep support
L-Ornithine HCl
1-2 weeks
24-48 hours post-exercise
30-60 minutes
With doses >10g
During prolonged exercise
Hours post-exercise
1-2 weeks
Immediate
Absence of Effects of L-Arginine and L-Citrulline on Inflammatory Biomarkers and Oxidative Stress in Response to Physical Exercise: A Systematic Review with Meta-Analysis
Nutrients (2023) · Meta analysis
We observed no difference between pre- vs. post-exercise for oxidative stress (subtotal = -0.21 [CI: -0.56, 0.14], p = 0.24, and heterogeneity = 0%.
Effects of Citrulline or Watermelon Supplementation on Body Composition: A Systematic Review and Dose-Response Meta-Analysis
Nutrients (2025) · Meta analysis
Overall, CIT supplementation had no substantial effects on body mass index (BMI), body weight, fat mass (FM), waist circumference (WC), body fat percentage (BFP), and fat-free mass (FFM).
Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials
Journal of the International Society of Sports Nutrition (2021) · Meta analysis
No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24).
Comparative Efficacy of Treatment Options for Minimal Hepatic Encephalopathy: A Systematic Review and Network Meta-Analysis
Clinical gastroenterology and hepatology : the official clinical practice journal of the American Gastroenterological Association (2020) · Meta analysis · n=1563
In a meta-analysis of data from 25 trials, we found rifaximin and lactulose to be most effective for reversal of minimal HE in patients with cirrhosis.
Safety assessment of L-ornithine oral intake in healthy subjects: a systematic review
Amino acids (2025) · Systematic review
Systematic review of 22 reports of oral L-ornithine in healthy people, up to 14,025 mg a day as L-ornithine hydrochloride and up to 156 days.
Efficacy of L-ornithine L-aspartate for minimal hepatic encephalopathy in patients with cirrhosis: A meta-analysis of randomized controlled trials
Arab journal of gastroenterology : the official publication of the Pan-Arab Association of Gastroenterology (2024) · Meta analysis · n=292
Meta-analysis of 6 randomised trials in 292 patients with cirrhosis and minimal hepatic encephalopathy, L-ornithine L-aspartate (LOLA) against placebo or no treatment.
L-Citrulline has a higher evidence score (6/10 vs 5/10) and wins in 2 of 3 categories.
For improve endurance, L-Citrulline has a higher relevance score (85 vs 65).
No documented interaction was found in the data searched. This does not establish that this exact combination is safe.
The right pick depends on your goals. Answer a few quick questions for a personalised recommendation — or dig into the full evidence on each.