Evidence Level
Strong
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.