L-Arginine
Also known as: arginine, L-arg, 2-amino-5-guanidinopentanoic acid, arginine alpha-ketoglutarate, aakg
Effective Dosage
3-9.6 g daily (clinical range from provided studies)
What the Science Says
L-Arginine is an amino acid your body uses to make nitric oxide (NO), a molecule that helps blood vessels relax and widen. In people with peripheral artery disease (leg circulation problems), oral supplementation at 6 g/day for up to 60 days improved nitric oxide levels and antioxidant status. One small crossover trial found a minor, short-lived increase in artery diameter after exercise, but no meaningful boost in muscle endurance or overall blood flow in healthy young men.
What It Doesn't Do
Won't boost your workout performance — clinical trials show no improvement in reps, strength, or endurance. Doesn't reliably raise nitric oxide levels in healthy people. Not a proven standalone treatment for high blood pressure. The 'pump' marketing claim is not supported by the evidence here. No proof it works as an anti-aging skin ingredient based on clinical data.
Evidence-Based Benefits
L-Arginine is an amino acid that serves as a precursor to nitric oxide, which can help improve blood flow and may enhance exercise performance. It has been shown in multiple systematic reviews and clinical trials to have potential benefits for cardiovascular health and exercise capacity.
Strong EvidenceEffective at: 3-6 g daily
Source: auto-research
Absorption & Bioavailability
Moderate — oral L-arginine is absorbed but much is broken down in the gut and liver before reaching circulation, which limits how much actually raises blood nitric oxide levels. Higher doses may partially overcome this.
Red Flags to Watch For
- High doses (above 9 g/day) may cause gastrointestinal side effects like nausea, diarrhea, and bloating
- People with herpes simplex virus should use caution — arginine can promote viral replication
- Not a substitute for prescribed cardiovascular medications; evidence for clinical benefit in vascular disease is still preliminary
- Supplements marketed for 'massive pumps' or 'extreme vascularity' are overstating what the science actually shows
- Topical L-arginine anti-aging creams lack robust clinical evidence from the provided studies
Products Containing L-Arginine
See how L-Arginine is used in these analyzed products:
Nutricost Nitric Oxide Booster Capsules
Supplement
Augustinus Bader The Hair Revitalizing Complex
Supplement
Transparent Labs Nitric Oxide
Supplement
Nitric Boost Ultra
Supplement
Elm & Rye Vegan Protein Blend
Supplement
Snapsupplements
Supplement
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: 2026-04-08