L-citrulline (free form and L-citrulline malate for sports formulas)

L-citrulline is marketed as a «natural Viagra», especially to men who avoid the doctor or urologist. The Cormio RCT (Urology 2011) in 24 men with mild erectile dysfunction (ED-Hardness Score 3 of 4) reported improvement in 50% on citrulline 1.5 g/day versus 8% on placebo at 1 month. The sample is small, duration short, and the result is not reproduced in larger RCTs. In men with moderate or severe ED, citrulline does not work: the AUA Guideline 2024 recommends phosphodiesterase-5 inhibitors as first-line (sildenafil 25-100 mg, tadalafil 5-20 mg on demand or 2.5-5 mg daily, vardenafil, avanafil); for contraindications or intolerance – vacuum devices, intracavernous alprostadil injections, implants. The Spanish AEU follows the same algorithm. Citrulline is not in these recommendations. A proper ED workup in a man over 40 includes cardiovascular-risk assessment (ED is an early atherosclerosis marker), diabetes screening, testosterone, and psychogenic factors. If citrulline was bought instead of evaluation, consider seeking a second opinion – ED after 50 deserves cardiology and endocrinology assessment, not a packet of powder.

L-citrulline and L-citrulline malate are among the best-selling pre-workout supplements; bodybuilders take them for «pump» (vasodilation and muscle blood flow), reduced muscle fatigue, and improved anaerobic tolerance. The evidence is moderate and heterogeneous. Meta-analyses of 10-15 RCTs describe a 6-9% increase in repetitions with 60-80% 1RM loads on 6-8 g citrulline malate taken 60 minutes pre-workout, reduced next-day muscle soreness, and a small increase in peak cycling power. Effects on VO2max and aerobic endurance are inconsistent. The Australian Institute of Sport places L-citrulline in Group B – «supplements with evidence of performance effect that need more research». The ergogenic effect is clinically modest for most amateur athletes; gains in the gym come from training programme, calorie balance, and sleep. In professional sport, citrulline in third-party certified forms (Informed Sport, NSF Certified for Sport) is considered safe and is not on the WADA prohibited list. Unverified supplements carry risk of contamination with stimulants and steroids.

L-citrulline is widely sold in pre-workout formulas promising «increased pump» and «better endurance» via NO-mediated vasodilation. Small RCTs are mixed: some show a moderate effect of citrulline malate 6-8 g/day on high-intensity performance and reduced post-exercise muscle soreness, others show none; aerobic endurance data are conflicting. EFSA 2024 recognised L-citrulline as safe; no physical performance claim approved. IOC consensus statement 2018 on sports supplements does not include L-citrulline in the proven-efficacy list.

L-citrulline is sold for «natural blood pressure reduction» on the NO-mediated vasodilation hypothesis. Small RCTs showed moderate systolic and diastolic BP reduction of 4-6 mm Hg with 6 g/day × 4-8 weeks in pre-hypertensive patients; less data in confirmed hypertension. ESC 2024 for hypertension lists ACE-I/ARB combined with dihydropyridine CCBs or thiazide-like diuretic first-line; L-citrulline is not mentioned. If L-citrulline was recommended for hypertension instead of supervised antihypertensive therapy and risk factor control, consider seeking a second opinion from a cardiologist.

L-citrulline is sold by marketers as a «universal vascular complex»: «improves circulation», «lowers blood pressure», «protects the heart», «rejuvenates skin via blood flow». Small RCT meta-analyses describe systolic BP reductions of 3-5 mm Hg and diastolic 1-3 mm Hg with 3-6 g/day for 2-8 weeks. The effect resembles a low dose of bisoprolol or perindopril but without strong reproducibility or hard endpoints (myocardial infarction, stroke, cardiovascular mortality). ESC Guidelines 2024 in hypertension recommend ACE inhibitors or ARBs (perindopril, lisinopril, enalapril, losartan, telmisartan, valsartan), calcium-channel blockers (amlodipine, lercanidipine, manidipine), thiazide diuretics (indapamide, chlortalidone), with combination therapy when needed; the Spanish SEH-LELHA follows the same algorithm. L-citrulline does not appear in these recommendations. Replacing proven antihypertensive therapy with citrulline in controlled hypertension yields uncontrolled BP and risks stroke and myocardial infarction.