Amino Acid
This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer
L-Citrulline at 3-6 g/day (or 6-8 g citrulline malate) is more effective than L-arginine at raising blood arginine and nitric oxide levels. It improves exercise performance, reduces fatigue, and enhances blood flow. A 2019 meta-analysis confirmed significant improvements in high-intensity exercise performance.
L-Citrulline has strong evidence as a nitric oxide booster and exercise performance enhancer. Its key advantage over arginine is bypassing first-pass liver metabolism, resulting in higher plasma arginine levels per gram consumed. Meta-analyses confirm performance benefits for high-intensity exercise. Citrulline malate (2:1) is the most popular pre-workout form, though pure L-citrulline is equally effective at lower doses.
L-Citrulline has strong evidence as a nitric oxide booster and exercise performance enhancer.
| Form | Bioavailability | Best For |
|---|---|---|
| L-Citrulline (pure) | High | Pure citrulline — 3-6 g provides effective arginine elevation |
| Citrulline Malate (2:1) | High | Combined with malic acid for potential additional ATP production; 6-8 g dose needed |
General recommendation: 3-6 g L-citrulline or 6-8 g citrulline malate 30-60 minutes before exercise
Timing: 30-60 minutes before exercise; can also be taken daily for ongoing NO support
| Condition | Recommended Dose | Evidence |
|---|---|---|
| Exercise performance | 6-8 g citrulline malate pre-workout | Strong |
| Blood flow/NO production | 3-6 g L-citrulline daily | Strong |
| Blood pressure support | 3-6 g daily | Moderate |
Upper limit: 10 g/day L-citrulline has been used safely; GI discomfort may increase at higher doses
Safety profile: Generally Safe
Yes, for raising blood arginine and nitric oxide levels. L-arginine undergoes extensive first-pass metabolism in the liver (arginase breaks it down), so much of an oral dose never reaches the bloodstream. L-citrulline bypasses the liver, is converted to arginine in the kidneys, and results in higher and more sustained plasma arginine levels.
Citrulline malate combines L-citrulline with malic acid (typically 2:1 ratio). The malate may provide additional benefits for ATP production via the Krebs cycle, though this is debated. To get 6 g of citrulline from a 2:1 citrulline malate, you need about 8 g of the combined product. Pure L-citrulline is fine if you just want the NO-boosting effects.
Take 30-60 minutes before exercise for peak plasma levels during your workout. For ongoing cardiovascular support, daily dosing is effective regardless of timing. Citrulline can be taken on an empty stomach and is often mixed into pre-workout drinks.