L-Arginine is a semi-essential amino acid best known for its role in nitric oxide (NO) production, which supports blood flow, cardiovascular health, and exercise performance. As a precursor to NO, L-arginine has become one of the most popular amino acid supplements for athletes and anyone seeking vascular health benefits.
How L-Arginine Works
L-Arginine is converted to nitric oxide by the enzyme nitric oxide synthase (NOS). Nitric oxide relaxes blood vessels (vasodilation), increasing blood flow to muscles and organs. This mechanism underlies most of arginine's health benefits.
L-Arginine Benefits
Cardiovascular Health
By promoting vasodilation, L-arginine helps reduce blood pressure, improve arterial function, and support overall cardiovascular health. Multiple studies show modest blood pressure reductions with supplementation.
Exercise Performance
Increased blood flow delivers more oxygen and nutrients to working muscles, potentially improving endurance and reducing fatigue. The "pump" experienced during resistance training is largely NO-mediated.
Erectile Function
Nitric oxide is essential for erectile function. L-arginine supplementation has shown benefit for mild to moderate erectile dysfunction, particularly when combined with pycnogenol.
L-Arginine Dosage by Goal
| Goal | Daily Dose | Timing |
|---|---|---|
| Blood pressure support | 6-10g | Split 2-3 doses |
| Exercise performance | 3-6g | 30-60 min pre-workout |
| Erectile function | 3-5g | Daily, split doses |
| General health | 2-3g | With meals |
L-Arginine vs L-Citrulline
| Factor | L-Arginine | L-Citrulline |
|---|---|---|
| Bioavailability | Lower (significant first-pass metabolism) | Higher (bypasses liver) |
| NO production | Direct precursor | Converted to arginine, then to NO |
| Blood arginine levels | Acute spike, shorter duration | Sustained elevation over hours |
| GI tolerance | May cause GI issues at high doses | Better tolerated |
| Research support | Extensive | Growing, often preferred |
| Typical dose | 3-10g | 3-8g (or 6-8g citrulline malate) |
Food Sources
| Food | Arginine per 100g |
|---|---|
| Turkey breast | 1.7g |
| Pumpkin seeds | 5.4g |
| Soybeans | 3.2g |
| Peanuts | 3.1g |
| Chicken breast | 1.4g |
| Lentils | 1.9g |
Frequently Asked Questions
What is L-Arginine used for?
L-Arginine is primarily used for cardiovascular health (blood pressure support, improved circulation), exercise performance (increased blood flow to muscles), and erectile function (nitric oxide-mediated vasodilation). It works by serving as the direct precursor to nitric oxide in the body.
Should I take L-Arginine or L-Citrulline?
L-Citrulline is generally preferred because it has better oral bioavailability and produces a more sustained elevation in blood arginine levels. L-Citrulline bypasses liver metabolism and is better tolerated at higher doses. However, both are effective, and some products combine them.
Does L-Arginine lower blood pressure?
Yes, meta-analyses show that L-arginine supplementation (6-10g daily) can produce modest reductions in both systolic and diastolic blood pressure through nitric oxide-mediated vasodilation. Effects are generally more pronounced in people with elevated blood pressure.
Conclusion
L-Arginine remains a well-researched amino acid for cardiovascular health and exercise performance. While L-Citrulline has emerged as a preferred alternative for NO boosting, arginine continues to have strong applications for blood pressure support and overall vascular health.