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Head-to-head evidence comparison — which supplement is right for you?
Arginine vs Ornithine: Arginine has the stronger overall evidence (7.5 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.
Arginine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
8 of 11 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
4 of 4 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Arginine and Ornithine have evidence — compare verdict strength side-by-side.
3-6g daily
30-60 minutes before exercise, Divided doses throughout the day for cardiovascular benefits
L-Arginine powder or capsules
2-6g daily
Before exercise for fatigue reduction, Before bed for sleep support
L-Ornithine HCl
30-60 minutes
During exercise
2-4 weeks
Immediate
During prolonged exercise
Hours post-exercise
1-2 weeks
Immediate
Nutritional interventions for preventing and treating pressure ulcers
The Cochrane database of systematic reviews (2024) · Meta analysis · n=7920
Compared to standard diet, protein supplements may result in little to no difference in pressure ulcer incidence (protein 21 per 1000, standard diet 28 per 1000; RR 0.75, 95% CI 0.49 to 1.14; 4 studies, 4264 participants; low-certainty evidence).
Comparative Effects of Different Nutritional Supplements on Inflammation, Nutritional Status, and Clinical Outcomes in Colorectal Cancer Patients: A Systematic Review and Network Meta-Analysis
Nutrients (2023) · Meta analysis · n=2841
Glutamine was superior in decreasing tumor necrosis factor-α (MD -25.2; 95% CrI [-32.62, -17.95]), whereas combined omega-3 and arginine supplementation was more effective in decreasing interleukin-6 (MD -61.41; 95% CrI [-97.85, -24.85]).
Nutritional interventions for treating foot ulcers in people with diabetes
The Cochrane database of systematic reviews (2020) · Meta analysis · n=629
It is also uncertain whether arginine, glutamine and β-hydroxy-β-methylbutyrate supplement increases the proportion of ulcers healed at 16 weeks compared with placebo (RR 1.09, 95% CI 0.85 to 1.40).
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.
From a dose-response meta-analysis of twenty-two randomised placebo-controlled trials (PMID 34967840): oral L-arginine lowered systolic blood pressure by 6.40 mmHg and diastolic by 2.64 mmHg overall, the effective dose for systolic pressure was 4 g a day or more, and trials using more than 9 g a day showed no significant change. That subgroup result is why the curve falls back at 9 g. It is a subgroup of pooled trials, not a trial that compared doses, so no optimal dose is given. An earlier meta-analysis of 11 trials at 4 to 24 g a day (PMID 22137067) found similar reductions (5.39 and 2.66 mmHg) without separating doses. Neither abstract reports side effects by dose.
AI-estimated from published studies. Interpret as directional guidance.
Arginine has a higher evidence score (7.5/10 vs 5/10) and wins in 2 of 3 categories.
Both Arginine and Ornithine score equally (65) for improve endurance.
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.