L-arginine
Conditionally essential amino acid with meta-analysis support for mild blood-pressure reduction and endothelial function.
Why
L-arginine is the immediate substrate for nitric oxide synthase. Meta-analyses of RCTs report modest reductions in systolic and diastolic blood pressure at doses of 4–24 g/day. Smaller bodies of work support endothelial-function improvement (flow-mediated dilation), exercise-tolerance gains in heart failure, and erectile-function improvement (often in combination with pycnogenol).
How it works
Substrate for endothelial nitric oxide synthase (eNOS), increasing nitric oxide bioavailability and promoting vasodilation. Effect is modest in healthy adults (substrate saturated) and larger in conditions with endothelial dysfunction (diabetes, hypertension, heart failure).
Expected onset · BP effects over 4–8 weeks; endothelial-function effects over 2–4 weeks
How to take
Dosage
Blood pressure: 4–9 g/day divided. Higher doses (up to 24 g/day) used in heart failure RCTs.
Timing
Divided 2–3 times daily, away from protein meals for absorption
On the label
'L-arginine HCl' or 'L-arginine free base' with stated milligrams. Sustained-release forms have better tolerability at therapeutic doses.
Ideal for
Adults with mild hypertension, endothelial-dysfunction risk factors, or seeking endothelial-supportive nutrition. Combined preparations with citrulline or pycnogenol have additional erectile-function evidence.
Safety
Evidence
Dong 2011 Am Heart J meta-analysis (11 RCTs, n=387): oral L-arginine reduced systolic BP by 5.4 mmHg and diastolic by 2.7 mmHg vs placebo. VINTAGE MI 2006 RCT raised a specific safety signal post-MI, 8.6% mortality on L-arginine vs 0% on placebo over 6 months, leading to avoidance recommendation in that setting. Outside post-MI, effect is real but modest.
Where to get it
Shop L-arginine on AmazonSponsored · As an Amazon Associate, Healicus earns from qualifying purchases.