L-arginine

L-arginine is sold to men with ED as «natural Viagra» on the NO-mediated cavernosal vasodilation hypothesis. Rhim 2019 (Sex Med Rev) systematic review of 10 RCTs in 540 patients with mild-to-moderate ED: L-arginine 1.5-5 g/day × 6 weeks showed moderate IIEF score improvement, effect comparable to or worse than PDE-5 inhibitors. AUA 2018 lists PDE-5 inhibitors (sildenafil, tadalafil, vardenafil, avanafil), vacuum devices and psychotherapy for psychogenic ED first-line; L-arginine is not mentioned in main international guidelines. If L-arginine was recommended for ED instead of standard therapy, consider seeking a second opinion from a urologist.

L-arginine is sold for «natural blood pressure reduction» on the NO-mediated vasodilation hypothesis. Dong 2011 (Am Heart J) meta-analysis of 11 RCTs in 387 patients: L-arginine 4-24 g/day reduces SBP by 5.4 mm Hg and DBP by 2.7 mm Hg – clinically weak effect. ESC 2024 for hypertension lists ACE-I/ARB combined with dihydropyridine CCBs or thiazide-like diuretic first-line; L-arginine is not mentioned. Important safety: after ESPRIM 2006 RCT in MI patients L-arginine did not improve LV function and was linked to increased mortality vs placebo – L-arginine is contraindicated in CHD and post-MI patients.

L-arginine is sold in pre-workout formulas as a «pump and endurance» product on the NO-mediated vasodilation hypothesis. Alvares 2011 (Sports Med) systematic review of RCTs in 200 subjects: L-arginine 5-9 g/day showed no clinically meaningful improvement in VO2max, time-to-exhaustion or other endurance metrics. EFSA 2014 approved no physical performance claim. IOC consensus statement 2018 does not include L-arginine in the proven-efficacy list. L-citrulline (see card) raises plasma arginine more effectively by bypassing intestinal first-pass.