Home/Ingredients/L-Arginine
AMINO ACIDS

L-Arginine

Nitric oxide · circulation · pump

MODERATE EVIDENCEVEGANREAD THE RESEARCH
Written to our editorial standards · reviewed against published research· Updated 2 Jun 2026
Last reviewed: May 30, 2026
QUICK ANSWER

L-Arginine: Nitric oxide · circulation · pump. A direct precursor to nitric oxide, supporting vasodilation, blood flow, and exercise performance. Standard dose 1500 mg, taken in the pre-workout, about $18/month. Evidence rating: moderate evidence.

What is L-Arginine?

L-Arginine is a conditionally essential amino acid and the primary substrate for nitric oxide synthase (NOS), the enzyme that produces nitric oxide. NO is a key signaling molecule that triggers vasodilation, supporting circulation, exercise pump, and erectile function. While arginine has lower oral bioavailability than its precursor citrulline, it remains useful at higher doses (3-6 g) before training. Combination with citrulline produces a longer sustained NO response than either alone. Avoid taking with herpes virus history (it may activate latent infection).

WHY IT MATTERS

A direct precursor to nitric oxide, supporting vasodilation, blood flow, and exercise performance.

Natural food sources

Where possible, get L-Arginine from whole foods first. Common dietary sources include:

Turkey & chickenPumpkin seedsPeanutsSoybeansLentils

Where to buy

NOW Foods L-Arginine 1000mg
RECOMMENDED
NOW Foods, L-Arginine
1500 mg · Pre-workout · ~$18/month

suppdoc.io is an affiliate. Links may earn us a commission at no extra cost to you.

Best for your goal

Interactions

Other amino acids

L-Theanine (Suntheanine)
Calm focus · stress
Glycine
Sleep depth · core body temperature
N-Acetyl Cysteine (NAC)
Liver · antioxidant · respiratory
Taurine
Heart · sleep · cellular hydration

Common questions

What is L-Arginine?
L-Arginine is a conditionally essential amino acid and the primary substrate for nitric oxide synthase (NOS), the enzyme that produces nitric oxide. NO is a key signaling molecule that triggers vasodilation, supporting circulation, exercise pump, and erectile function. While arginine has lower oral bioavailability than its precursor citrulline, it remains useful at higher doses (3-6 g) before training. Combination with citrulline produces a longer sustained NO response than either alone. Avoid taking with herpes virus history (it may activate latent infection).
What is L-Arginine used for?
Nitric oxide · circulation · pump. A direct precursor to nitric oxide, supporting vasodilation, blood flow, and exercise performance.
What is the standard dose of L-Arginine?
1500 mg, typically taken in the pre-workout. Approximate cost is $18 per month.
How strong is the evidence for L-Arginine?
Moderate evidence for its primary uses. See the full study list on the research page.

Not sure if L-Arginine is right for you?

Take our quiz. We'll compose a personalised stack that fits your goals, body, and budget, in minutes.

Take the quiz →