Quick answer
Studies used 2 to 20 g of L-arginine a day, most often 2 to 10 g in one dose, while a normal diet already supplies about 4 to 5 g. Up to 9 g a day for days or weeks is well tolerated in most studies. No amount has been shown to make a reliable difference to performance.1
Key facts
- In the studies that tested arginine alone against a placebo, amounts up to 20 g a day were split into three doses.1
- No official upper limit is set for arginine.1
- A quarter of US adults take in less than 2.6 g of arginine a day from food, and a tenth more than 7.5 g.2
- None of the 54 studies in the review NIH cites lasted 3 months or longer.1
The amounts used in studies
Exercise studies have used 2 to 20 g of arginine a day, for up to 3 months.1,3
In the 18 studies that compared arginine alone with a placebo, the most common amounts were 2 to 10 g a day taken as one dose, and up to 20 g a day split into three doses.1
| What | Amount a day |
|---|---|
| Average US diet | About 4.4 g |
| A nutritious diet, per NIH | About 4 to 5 g |
| Exercise studies | 2 to 20 g |
| Well tolerated for days or weeks | Up to 9 g |
| Range where stomach complaints are most reported | 9 to 30 g |
Set against those figures, a 500 mg or 1,000 mg capsule is small. It is roughly a ninth or a fifth of what an average diet already supplies, and a quarter or a half of the lowest daily amount studied.1,2
Is there a dose for exercise?
There is no evidence-based dose for performance, because the trials did not show a reliable effect at any amount. NIH's summary covers 2 to 20 g a day for both aerobic and anaerobic exercise.1
A 2020 pooled analysis proposed single doses of 0.15 g per kg of body weight taken 60 to 90 minutes before exercise, or daily amounts of 1.5 to 2 g for 4 to 7 weeks or 10 to 12 g for 8 weeks. In 2025 a published comment showed calculation errors that inflated its estimates, and the authors acknowledged them.4,5,6
That proposal still circulates, often as 0.15 g per kg before training. For a person weighing 80 kg it comes to 12 g at once, more than the 9 g a day that NIH describes as well tolerated.1,4
Splitting the dose, and how long studies ran
In the review of 54 studies that NIH cites, most lasted 4 to 8 weeks and none lasted 3 months or longer.1
Larger daily amounts in the studies were split into three doses, while smaller ones were usually taken all at once. The sources we use give no reason to prefer a particular time of day.1
Because no study lasted three months, NIH says the safety of high doses taken for longer is not known.1
What's in ours
What’s in ours
- Ashwagandha Complex: L-Arginine, 300 mg per serving, from the label
Our Ashwagandha Complex has 300 mg of L-arginine per serving, well below the 2 g a day at the bottom of the studied range. We make no claim for it.1
Who should ask before taking it
No official upper limit is set for arginine. NIH says most studies suggest that up to 9 g a day for several days or weeks is safe and well tolerated, and that the safety of high doses beyond 3 months is not known.1
Arginine can lower blood pressure. NIH notes a slight drop at 9 to 30 g a day, and a 2022 pooled analysis of 22 trials found systolic pressure about 6.4 mmHg and diastolic pressure about 2.6 mmHg lower than with placebo, with the systolic drop seen from about 4 g a day.1,7
- Anyone who has recently had a heart attack should not take it8
- Ask first if you take medicine for blood pressure or your heart
- Ask first if you have kidney disease, are pregnant or nursing, or are under 18
Questions people ask
Is 1,000 mg of L-arginine a day enough?
Enough for what? No amount has been shown to make a reliable difference to performance. As a share of intake, 1,000 mg is about a fifth of what an average US diet already supplies.1,2
How much L-arginine for bodybuilding?
Trials in strength and power exercise used 2 to 20 g a day and found little to no effect, so there is no dose to recommend. At 9 to 30 g a day, stomach discomfort is the side effect reported most often.1
Is the dose different for women?
There is no separate dose. Only four of the 54 studies in one review included women, so there is little to go on either way.1
See what we make
Every product shows its whole label and what its lab report covers. The store opens soon.
Sources
- National Institutes of Health, Office of Dietary Supplements. Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals. Updated April 1, 2024. Opened 2026-10-07.
- Wu G, Bazer FW, Davis TA, et al. Arginine metabolism and nutrition in growth, health and disease. Amino Acids. 2009;37(1):153-168. Opened 2026-10-07.
- National Institutes of Health, Office of Dietary Supplements. Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Consumers. Updated March 22, 2021. Opened 2026-10-07.
- Viribay A, Burgos J, Fernández-Landa J, Seco-Calvo J, Mielgo-Ayuso J. Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis. Nutrients. 2020;12(5):1300. Opened 2026-10-07.
- Trexler ET. Common Errors in Sports Nutrition Meta-Analyses Lead to Distortion of Pooled Effect Estimates. Comment on Viribay et al. Nutrients 2020, 12, 1300. Nutrients. 2025;17(14):2375. Opened 2026-10-07.
- Viribay A, Fernández-Landa J, Seco-Calvo J, Mielgo-Ayuso J. Reply to Trexler, E.T. Common Errors in Sports Nutrition Meta-Analyses Lead to Distortion of Pooled Effect Estimates. Nutrients. 2025;17(14):2376. Opened 2026-10-07.
- Shiraseb F, Asbaghi O, Bagheri R, Wong A, Figueroa A, Mirzaei K. Effect of l-Arginine Supplementation on Blood Pressure in Adults: A Systematic Review and Dose-Response Meta-analysis of Randomized Clinical Trials. Adv Nutr. 2022;13(4):1226-1242. Opened 2026-10-07.
- Schulman SP, et al. L-arginine therapy in acute myocardial infarction: the Vascular Interaction With Age in Myocardial Infarction (VINTAGE MI) randomized clinical trial. JAMA. 2006;295(1):58-64. Opened 2026-10-07.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.