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

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 marketed as a «natural Viagra», especially to men who avoid the doctor or urologist. A small single-blind non-randomized study (Cormio, Urology 2011, 24 men, mild ED, crossover design: one month placebo then one month citrulline) reported improvement in 50% on citrulline 1.5 g/day versus 8% during the placebo period. 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.

ICD-10: N52.9 · ICD-11: HA01.1

L-citrulline is sold for «natural blood pressure reduction» on the NO-mediated vasodilation hypothesis. A 2025 meta-analysis shows systolic BP reduction of about 4 mm Hg and diastolic about 2.5 mm Hg, while a citrulline-only pooled meta-analysis (2018) found no significant BP effect; samples were mostly middle-aged and elderly. 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.

ICD-10: I10 · ICD-11: BA00

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.