Evidence Level
Moderate
L-Arginine has solid evidence for blood pressure reduction (meta-analysis: -5.4 mmHg systolic) and emerging evidence for erectile dysfunction. However, its bioavailability is limited by extensive first-pass metabolism via arginase in the gut and liver. L-Citrulline bypasses this metabolism and may be more effective at sustaining elevated arginine and NO levels. Arginine remains useful for wound healing and as part of cardiovascular support protocols.