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L-arginine: how much to take

L-arginine is used to make nitric oxide, which widens blood vessels. It is studied mainly for blood pressure.

Calculator Official intake Study doses Best form Safety Sources

Adults 18+ only
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Official daily intake

This is not an essential nutrient, so there is no official daily intake. Only study doses are shown.

Doses used in studies

These are doses tested in research, not personal advice. Some exceed the upper limit because they were short courses or given under medical care.

Moderate evidenceModerate: smaller trials, mixed results or official guidance.Based on 1 meta-analysis. 1 finding disagrees.How grades work

Lower blood pressure

4-9 g a day

A dose-response meta-analysis of 22 trials found systolic pressure about 6.4 mmHg and diastolic about 2.6 mmHg lower. The effect showed from about 4 g a day; doses above 9 g a day showed no significant change.

Shiraseb F et al. 2022

Other findings

VINTAGE MI gave 3 g three times a day after a heart attack: no benefit, and 6 of about 70 patients on arginine died against none on placebo, so the trial was stopped early. Avoid after a heart attack.

Schulman SP et al. 2006

Best form and why

No best form

Why: Trials used L-arginine; if your label gives arginine HCl weight, count about 83% of it.

Shiraseb F et al. 2022 · Shao A, Hathcock JN 2008

Forms and labels

  • Label shows L-arginine
  • L-arginine HCl, full weight (~83% arginine)

L-arginine HCl is about 83% arginine by its formula.

Food sources

Meat, poultry, fish, dairy, nuts and seeds, legumes.

Interactions

Adds to blood pressure medicines, nitrates and erectile dysfunction drugs. Avoid after a heart attack.

Safety

A risk assessment found strong evidence of safety up to 20 g a day in healthy adults. Stomach upset is common at high doses.

Pregnant, breastfeeding, on medication, or managing a health condition? Check with a doctor or pharmacist before starting a supplement.

Sources

  1. Meta-analysis Shiraseb F et al. (2022). Effect of L-arginine supplementation on blood pressure in adults: a systematic review and dose-response meta-analysis of randomized clinical trials. Adv Nutr 13:1226-1242
  2. Randomised trial Schulman SP et al. (2006). L-arginine therapy in acute myocardial infarction: the VINTAGE MI randomized clinical trial. JAMA 295:58-64
  3. Review / position paper Shao A, Hathcock JN (2008). Risk assessment for the amino acids taurine, L-glutamine and L-arginine. Regul Toxicol Pharmacol 50:376-399

Values checked: November 12, 2026.

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