Citrulline (L-citrulline, pure form)

Tier 2 — promising · Blood flow · Exercise · Blood pressure

Converted to arginine in the kidneys, then to nitric oxide for vasodilation. More effective at raising blood arginine than arginine supplements themselves because it bypasses first-pass liver metabolism. Meta-analyses (Mirenayat 2020; Barkhidarian 2019) of short-term RCTs report small-to-moderate reductions in systolic and diastolic blood pressure with 3–6 g/day, though effects in untreated normotensives are less clear. Also improves exercise blood flow and reduces post-exercise muscle soreness. Very safe.

Dose: 3–6 g/day L-citrulline for blood pressure; 6–8 g/day 30–60 min before exercise for performance