L-arginine

L-arginine is an amino acid and a nitric oxide precursor that marketing links to a longer life and slower aging. No large clinical trial shows that L-arginine supplements extend human lifespan or reverse aging. EFSA reviewed the proposed L-arginine effects (immune function, blood vessels, physical performance and others) and found no cause-and-effect relationship for any of them, and the EU has authorized no anti-aging claim. Laboratory work shows that prolonged L-arginine exposure accelerates endothelial cell senescence, and in the VINTAGE MI trial high doses raised mortality in patients after a heart attack. In healthy adults at usual doses the supplement is tolerated, but it offers no longevity benefit.

L-arginine is sold in pre-workout formulas as a «pump and endurance» product on the NO-mediated vasodilation hypothesis. The Alvares 2011 (Sports Med) systematic review of exercise RCTs found mixed results (some acute and chronic trials positive, others not) and judged it premature to recommend arginine as ergogenic. Doses up to 20 g are well tolerated. 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.

L-arginine is sold to men with ED as «natural Viagra» on the NO-mediated cavernosal vasodilation hypothesis. The Rhim 2019 (Sex Med Rev) meta-analysis in mild-to-moderate ED found a positive signal (OR 3.37; 95% CI 1.29–8.77): arginine improved erection more often than placebo. The data are low quality: small heterogeneous RCTs (I2=44%), part of the effect from combinations, and no head-to-head against PDE-5 inhibitors. Use caution with nitrates and PDE-5 inhibitors due to additive hypotension. 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.

ICD-10: N52.9 · ICD-11: HA01.1

L-arginine is widely marketed to bodybuilders as a way to raise growth hormone and speed up muscle gain. Intravenous arginine does raise growth hormone, but oral doses do not reproduce this effect: the amounts needed for a meaningful hormone response tend to cause nausea and diarrhoea. Meta-analyses and systematic reviews find no gain in strength, endurance or muscle mass in trained people. In one trial, arginine taken before resistance exercise actually lowered the growth hormone rise compared with placebo. EFSA did not accept the claims linking L-arginine to muscle mass or physical performance.

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: the VINTAGE MI RCT (Schulman, JAMA 2006) in post-MI patients was stopped early – arginine did not improve LV function and was linked to excess mortality (6 deaths vs 0 on placebo). Arginine should be avoided in coronary heart disease and after MI.

ICD-10: I10 · ICD-11: BA00