L-Arginine: What It Is, What the Research Shows and How to Take It
L-arginine is an amino acid often chosen by people who exercise. We get it from protein-rich foods, and the body also produces some of it itself.
In this article, you will learn what the research shows, how the different forms of arginine differ and when it is better not to take it.
In brief. Arginine is a popular amino acid of interest to both people who exercise and older adults. Scientists are studying it from various angles, and its effect may vary from person to person.¹ Studies have mostly used larger amounts than a single capsule contains, so it is worth reading the label carefully. Arginine may slightly lower blood pressure. If you take medicines for your heart or blood pressure, talk to your doctor before starting the supplement.2
What is arginine?
Arginine is one of the amino acids that make up proteins. The body uses it to produce nitric oxide, a substance that helps blood vessels relax.2 This is why arginine is often studied in relation to blood pressure and sport.
A healthy person gets enough arginine from food and also produces it themselves. Deficiency is rare.2
Which foods contain arginine?
Arginine is found in almost all proteins. The richest sources are meat, fish, dairy products, eggs, nuts, seeds and legumes.2
Example. If you eat meat or fish, a handful of nuts and a lentil dish every day, you are already getting arginine from your food. A supplement does not improve your diet by itself.
What does the research show?
Blood pressure. In a review of 11 studies with 387 participants, arginine (4–24 g per day) lowered blood pressure only slightly: systolic pressure by about 5 mmHg on average and diastolic pressure by about 3 mmHg.3 The studies were small. A supplement does not replace medicines prescribed by your doctor.
Sport. In a review of 18 studies, arginine slightly improved some endurance and short high-intensity exercise results.4 However, the doses were high, for example 0.15 g per kilogram of body weight taken 60–90 minutes before training. For a 70 kg person, this would be about 10 g, i.e. about 20 capsules of 500 mg.
What this means for you. The results are modest and were achieved with doses well above a typical supplement serving. So you should not expect a quick or noticeable effect from arginine.
What forms of arginine are there?
| Form | What to know | What this means for you |
|---|---|---|
| L-arginine (free form) | The most studied form.3 | A capsule usually contains 500 mg. |
| AAKG (arginine alpha-ketoglutarate) | Arginine bound to another substance. | 3,200 mg of AAKG is not 3,200 mg of arginine – it contains less pure arginine. |
| Arginine with citrulline | Citrulline is another amino acid from which the body produces arginine. | If you take several products, add up the amounts of both substances. |
How much arginine should you take?
There is no recommended daily intake for arginine. Follow the dose stated on the label. If you are considering higher doses, such as those used in studies, talk to your doctor first.
Example. If you take a pre-workout powder and a separate arginine supplement, check the ingredients of both products. Arginine and citrulline are often included in such powders.
When is it better not to take arginine?
The most common side effects are nausea, bloating and diarrhoea.2
Talk to your doctor first if you:
- have had a heart attack or have heart disease – in a study of people after a heart attack, arginine did not improve heart function, so the study was stopped;5
- take blood pressure-lowering medicines, nitrates or erectile dysfunction medicines (e.g. sildenafil) – your blood pressure may drop too much;2
- have kidney or liver disease;
- are pregnant or breastfeeding, or want to give the supplement to a child.
If you feel very dizzy or have chest pain after taking arginine, stop taking it and call 112.
Selected arginine products
Commercial information. The products below are available in our shop. This is not an effectiveness ranking. Before buying, check the ingredients and directions for use on the product page.
L-Arginine, 500mg - 100 caps - NOW Foods
Free-form L-arginine, 1 g in two capsules. The manufacturer recommends taking it between meals or before bedtime.6
AjiPure L-Arginine - 500 mg - 60 capsules - L-Arginine - Swanson
L-arginine produced by fermentation, 500 mg per capsule. The manufacturer recommends 1 capsule 1–2 times a day.7
Arginine & Citrulline - 120 vcaps - NOW Foods
Each capsule contains 500 mg of L-arginine and 250 mg of L-citrulline. Take 1 capsule 2 times a day. If you also take another product containing citrulline, add up the amounts.8
AAKG, 3200mg - 120 capsules - Applied Nutrition
Arginine alpha-ketoglutarate, 3,200 mg in four capsules. This is the amount of the compound, not of pure arginine. The capsules are suitable for vegans.9
Frequently asked questions
When should I take arginine – before training or at another time?
In sports studies, arginine was most often taken 60–90 minutes before exercise.4 Otherwise, follow the manufacturer's instructions.
What is the difference between arginine and citrulline?
They are two different amino acids. The body can produce arginine from citrulline, which is why they are often combined in one product.
What other supplements are popular among people who exercise?
We write more about this in the article Supplements for people who exercise.
Scientific sources
- EFSA NDA Panel. Scientific opinion on the substantiation of health claims related to L-arginine pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal. 2011;9(4):2051. doi:10.2903/j.efsa.2011.2051
- MedlinePlus, U.S. National Library of Medicine. L-arginine. medlineplus.gov
- Dong JY, Qin LQ, Zhang Z et al. Effect of oral L-arginine supplementation on blood pressure: a meta-analysis of randomized, double-blind, placebo-controlled trials. Am Heart J. 2011;162(6):959–965. doi:10.1016/j.ahj.2011.09.012
- Viribay A, Burgos J, Fernández-Landa J et al. Effects of arginine supplementation on athletic performance based on energy metabolism: a systematic review and meta-analysis. Nutrients. 2020;12(5):1300. doi:10.3390/nu12051300
- Schulman SP, Becker LC, Kass DA 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. doi:10.1001/jama.295.1.58
- NOW Foods. L-Arginine, 500 mg, 100 capsules. Product label.
- Swanson. AjiPure L-Arginine, 500 mg, 60 capsules. Product label.
- NOW Foods. Arginine & Citrulline, 120 capsules. Product label.
- Applied Nutrition. AAKG, 3200 mg, 120 capsules. Product label.
Disclaimer. This article is for information purposes only and does not replace a consultation with a doctor or pharmacist. Food supplements are not intended to treat or prevent diseases and should not be used as a substitute for a varied diet and a healthy lifestyle. Before taking supplements, especially during pregnancy or breastfeeding, if you have a chronic condition or if you take medicines, consult a healthcare professional.
