Last verified: 17 days ago
L-Arginine
Also known as: arginine, L-Arg, ARG, 2-amino-5-guanidinopentanoic acid
Evidence under review. — Not yet rated
Amino acid that boosts nitric oxide. Modest vascular benefits; limited evidence for athletic performance.
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What it does
L-Arginine is an amino acid that the body uses to produce nitric oxide (NO), a molecule that relaxes and widens blood vessels. Clinical studies show it can improve blood flow markers and...
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Evidence quality
Evidence base hasn't been formally rated yet. See research below.
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Clinical dose
3.2-9.6 g daily (fitness); 6 g daily (vascular); 4.5 g daily (wound healing)
What the Science Says
L-Arginine is an amino acid that the body uses to produce nitric oxide (NO), a molecule that relaxes and widens blood vessels. Clinical studies show it can improve blood flow markers and antioxidant status in people with peripheral artery disease, and may support wound healing when combined with vitamins C and E. At doses of 3–10 g per day, effects on vascular function appear within 30–60 days, though benefits for athletic performance in healthy individuals are modest at best.
What It Doesn't Do
Won't give you a meaningful pump or boost muscle endurance in healthy athletes. Doesn't reliably raise nitric oxide levels during exercise. Not a proven muscle-builder. Don't expect it to replace blood pressure medication. No strong evidence it speeds recovery from hard training.
Evidence-Based Benefits
Improves nitric oxide levels and walking distance in people with peripheral artery disease.
Moderate EvidenceEffective at: 6 g/day for 30–60 days
Supporting studies (click to view on PubMed):
Reduces venous leg ulcer size when added to standard wound care over 8 weeks.
Weak EvidenceEffective at: 4.5 g/day (with vitamins C and E)
Supporting studies (click to view on PubMed):
Does not meaningfully improve muscle endurance or nitric oxide during exercise in healthy young men.
Weak EvidenceEffective at: 3.2–9.6 g/day for 4 days
Supporting studies (click to view on PubMed):
Absorption & Bioavailability
Moderate — oral L-arginine is absorbed but subject to significant first-pass metabolism in the gut and liver, which limits how much reaches circulation. Higher doses partially compensate, but absorption efficiency decreases at very high intakes.
Red Flags to Watch For
- High doses (>10 g/day) can cause gastrointestinal distress including nausea, diarrhea, and cramping
- May interact with blood pressure medications and nitrates — consult a doctor if you take these
- L-arginine supplementation has been associated with worsening outcomes in some cardiovascular patients — not appropriate for everyone with heart disease
- Used experimentally to induce pancreatitis in animal models at high doses — relevance to human supplementation is unclear but warrants caution at very high doses
- Evidence for ergogenic (performance-enhancing) benefits in healthy athletes is weak despite widespread marketing claims
Products Containing L-Arginine
See how L-Arginine is used in these analyzed products:
1.M.R OG Pre-Workout Formula
Supplement
Augustinus Bader The Hair Revitalizing Complex
Supplement
Vitabiotics Neuromind Plus
Supplement
C4 Original Pre-Workout
Nutricost Nitric Oxide Booster Capsules
Supplement
Elm & Rye Vegan Protein Blend
Supplement
Transparent Labs Nitric Oxide
Supplement
Snapsupplements
Supplement
Nitric Boost Ultra
Supplement
Optimum Nutrition 100% Gold Standard Whey
Supplement
In The Mood Capsules
Supplement
Everyday Dose
Supplement
Frequently Asked Questions
What does L-Arginine do?
Amino acid that boosts nitric oxide. Modest vascular benefits; limited evidence for athletic performance.
What is the effective dose of L-Arginine?
3.2-9.6 g daily (fitness); 6 g daily (vascular); 4.5 g daily (wound healing)
Is L-Arginine safe?
High doses (>10 g/day) can cause gastrointestinal distress including nausea, diarrhea, and cramping
What doesn't L-Arginine do?
Won't give you a meaningful pump or boost muscle endurance in healthy athletes.
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-05-25