L-arginine: what it is, what studies show and who should avoid it
L-arginine is an amino acid often chosen by people who exercise and by those interested in blood vessel health. It is found in protein-rich foods, and the body also produces some of it on its own.
In this article you will learn what the research actually shows, what forms of arginine supplements are available and when it is better not to take them.
In brief. There are no authorised EU health claims for arginine.1 In studies, high doses (4–24 g per day) lowered blood pressure slightly, while the results of sports studies are mixed.2,3 Arginine may interact with blood pressure medicines and nitrates, and it should not be taken after a heart attack.4,5
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. This is why arginine is studied in relation to blood pressure and sport.
With an ordinary diet, people get about 5–7 g of arginine per day, and the body produces even more on its own.5 Deficiency is rare in healthy people.
Which foods contain arginine?
Arginine is found in proteins, so it is most abundant in protein-rich foods: meat, fish, dairy products, eggs, nuts, seeds and legumes.
Example. If you eat meat or fish every day, a handful of nuts and a lentil dish, you already get arginine from food. A supplement is usually only needed when you want a higher dose than food provides.
What do studies show about arginine?
Blood pressure
In a review of 11 studies with 387 participants, arginine (4–24 g per day) lowered systolic blood pressure by about 5 mmHg on average and diastolic blood pressure by about 3 mmHg.2 This is a small change, and the studies were small. A supplement does not replace medicines prescribed by a doctor.
Sport
In a review of 18 studies, arginine slightly improved endurance and the results of short, intense exercise.3 However, the doses were high: for example, 0.15 g per kilogram of body weight 60–90 min before training. For a person weighing 70 kg, that would be about 10 g.
What does this mean when choosing a supplement?
So far the evidence is not sufficient for the EU to allow statements about the effects of arginine on muscles, blood circulation or physical performance to be made on products.¹ That is why you will not find such promises on labels – this is normal and does not mean the product is of poor quality. When choosing, the most important thing is to look at the form of arginine and the amount per serving.
What forms of arginine are available?
| Form | What is worth knowing | What this means for you |
|---|---|---|
| L-arginine (free form) | The most commonly studied form.2,3 | Capsules usually contain 500–1,000 mg, so the doses used in studies would require many capsules. |
| AAKG (arginine alpha-ketoglutarate) | Arginine combined with another substance. | 3,200 mg of AAKG is not 3,200 mg of arginine. The amount of pure arginine is lower. |
| Arginine with citrulline | Citrulline is another amino acid from which the body makes arginine. | Add up the amount of both substances if you take several products. |
How much arginine should you take?
There is no recommended daily intake or EU upper safe intake level for arginine. Some countries limit the amount in supplements: for example, the Portuguese food authority accepts supplements whose daily dose contains no more than 1,250 mg of arginine.5
Follow the dose stated on the label. Discuss higher doses, such as those used in studies, with your doctor first.
Side effects and safety of arginine
The most common side effects are nausea and vomiting.5 The most serious warning relates to the heart.
Example. In a study of 153 people after a heart attack, arginine (3 g three times a day for 6 months) did not improve heart function. Six people died in the arginine group and none in the placebo group, so the study was stopped early.4
Do not take arginine, or talk to your doctor first, if:
- you have had a heart attack or have heart disease;4
- you take blood pressure-lowering medicines, nitrates or erectile dysfunction medicines (e.g. sildenafil) – blood pressure may drop too much;5
- you are pregnant or breastfeeding, or want to give the supplement to a child;
- you have kidney or liver disease.
If after taking arginine you feel severe dizziness, your vision darkens or you feel chest pain, stop taking it and seek help (112). A supplement is not a substitute for a varied diet.6
Selected arginine products
Commercial information. The products listed here are available in our shop. This is not an effectiveness ranking. Before buying, check the composition and instructions for use on the product page.
L-Arginine, 500mg - 100 caps - NOW Foods
Free-form L-arginine in capsules, 1 g per serving (2 capsules). The manufacturer recommends taking it between meals.7
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 per day.8
Arginine & Citrulline - 120 vcaps - NOW Foods
Each capsule contains 500 mg of L-arginine and 250 mg of L-citrulline. Take 1 capsule twice a day.9
AAKG, 3200mg - 120 capsules - Applied Nutrition
Arginine alpha-ketoglutarate, 3,200 mg per serving (4 capsules). This is the amount of the compound, not of pure arginine.10
Frequently asked questions
Does arginine help with exercise?
Some studies show a small improvement, but high doses were used, and there is no authorised EU claim.1,3 You can read more about sports supplements in the article “Supplements for athletes”.
Can arginine be taken with blood pressure medicines?
Only after talking to your doctor. Arginine may lower blood pressure further.5
What is the difference between arginine and citrulline?
They are two different amino acids. The body can make arginine from citrulline, so they are often combined in one product.
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
- 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
- Direção-Geral de Alimentação e Veterinária (DGAV, Portugal). Arginina em suplementos alimentares. 2017. infarmed.pt
- Directive 2002/46/EC on the approximation of the laws of the Member States relating to food supplements. EUR-Lex
- 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 consultation with a doctor or pharmacist. Food supplements are not intended to treat or prevent diseases and are not 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.
