L-Citrulline
PromisingBoosts nitric oxide for better blood flow and exercise performance.
Not medical advice
Nutripedia summarises published peer-reviewed research. This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before taking any supplement.
L-Citrulline is an amino acid that converts to L-arginine in the kidneys, increasing nitric oxide production. This improves blood flow, reduces fatigue, and may enhance both aerobic and anaerobic performance.
Growing evidence for improved exercise performance and reduced fatigue. More effective than supplementing L-arginine directly.
Evidence Database
Click any row to explore the studies behind each health outcome. Grades reflect the volume and quality of published research, not a recommendation.
| Grade | Health Outcome |
|---|
Supplier Directory
Verified UK retailers ranked by trust and transparency. Certification badges show which quality standards each supplier meets.
Cost Comparison
Top 5 cheapest options by daily cost. Click column headers to re-sort. Prices in GBP.
| Form | |||||||
|---|---|---|---|---|---|---|---|
| No products found for this format. | |||||||
General Information
Dosage (Evidence-Reported)
These figures reflect what clinical studies used — not personalised recommendations.
Safety Notes
- May interact with blood pressure medications
- High doses can cause gastrointestinal discomfort
Key Benefits
- Increases nitric oxide and blood flow
- May reduce muscle soreness post-exercise
- Supports both aerobic and anaerobic performance
Quick Facts
Nutripedia is an educational resource. Content is sourced from peer-reviewed studies and does not constitute medical advice. Consult a healthcare professional before starting any supplement.
The Evidence
15 peer-reviewed papers, updated yesterday
8 meta-analyses · 4 systematic reviews · 2 RCTs · 1 cohort study
Does l-citrulline supplementation and watermelon intake reduce blood pressure in middle-aged and older adults? A systematic review and meta-analysis of randomized controlled trials
Ping Luo, Jingfeng Chen, Kang Liu et al.
Clinical Nutrition ESPEN
Meta-analysis of 15 RCTs (415 participants, 24 datasets) found l-citrulline and watermelon intake significantly reduced systolic BP by 4.02 mmHg and diastolic BP by 2.54 mmHg in middle-aged and older adults. Combined L-citrulline + L-arginine was superior to either intervention alone, suggesting additive cardiovascular benefit.
Citrulline in the management of patients with urea cycle disorders
Apolline Imbard, Juliette Bouchereau, Jean-Baptiste Arnoux et al.
Orphanet Journal of Rare Diseases
Retrospective analysis of 79 urea cycle disorder patients showed citrulline supplementation (alone or with arginine) effectively controlled ammonia levels, with citrulline monotherapy achieving lower mean ammonia (35.9 µmol/L) than arginine alone (49.8 µmol/L). Citrulline is the preferred single-agent option for raising plasma arginine.
Effects of citrulline on endurance performance in young healthy adults: a systematic review and meta-analysis
Callum S Harnden, Joseph Agu, Tom Gascoyne
Journal of the International Society of Sports Nutrition
Analysis of 9 RCTs (158 participants) found no significant difference in endurance performance (time-to-exhaustion or time-to-completion) following citrulline supplementation vs placebo. Authors recommend further research with higher doses, longer loading periods, and female-inclusive populations before conclusions can be drawn.
Effects of Citrulline Supplementation on Different Aerobic Exercise Performance Outcomes: A Systematic Review and Meta-Analysis
Viribay A, Fernández-Landa J, Castañeda-Babarro A et al.
Nutrients
Meta-analysis of 10 controlled trials found no significant benefit of citrulline supplementation on aerobic exercise performance, RPE, VO2 kinetics, or blood lactate compared to placebo (pooled SMD = 0.15, p = 0.08). Current evidence does not support citrulline for aerobic performance enhancement.
Effects of Citrulline Malate Supplementation on Muscle Strength in Resistance-Trained Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Andreo F Aguiar, Juliano Casonatto
Journal of Dietary Supplements
Meta-analysis of 4 RCTs (138 assessments) found no significant effect of citrulline malate on upper or lower body muscle strength in healthy resistance-trained individuals. Despite proposed ergogenic mechanisms, supplementation did not translate to meaningful strength gains in this population.
Effects of l-citrulline supplementation and watermelon consumption on longer-term and postprandial vascular function and cardiometabolic risk markers: a meta-analysis of randomised controlled trials in adults
Smeets ETHC, Mensink RP, Joris PJ
British Journal of Nutrition
Meta-analysis of 17 RCTs found longer-term L-citrulline supplementation significantly improved brachial artery flow-mediated vasodilation (FMD) by 0.9 percentage points (p < 0.001). Watermelon consumption improved pulse wave velocity. No postprandial effects on vascular function were detected. Suggests a cardiovascular benefit with sustained supplementation.
Acute L-Citrulline Supplementation Increases Nitric Oxide Bioavailability but Not Inspiratory Muscle Oxygenation and Respiratory Performance
Theodorou AA, Zinelis PT, Malliou VJ et al.
Nutrients
Double-blind crossover RCT (12 healthy males, 6 g L-citrulline vs placebo) confirmed single-dose citrulline significantly increased exhaled nitric oxide bioavailability, but did not improve inspiratory muscle oxygenation or respiratory performance during a fatiguing incremental resistive breathing protocol.
A critical review of citrulline malate supplementation and exercise performance
Lewis A Gough, S Andy Sparks, Lars R McNaughton et al.
European Journal of Applied Physiology
An acute 8 g dose of citrulline malate may modestly improve muscular endurance-strength performance, but evidence is inconsistent. Little support exists for benefits to power, maximal strength, or recovery. Methodological variability and product quality control issues limit interpretation across the literature.
Acute Effect of Citrulline Malate on Repetition Performance During Strength Training: A Systematic Review and Meta-Analysis
Fredrik Tonstad Vårvik, Thomas Bjørnsen, Adam M Gonzalez
International Journal of Sport Nutrition and Exercise Metabolism
Acute citrulline malate supplementation (6–8 g, 40–60 min pre-exercise) increased repetitions to failure by ~3 reps (6.4%) vs placebo across 8 studies and 137 participants. The ergogenic effect was small but statistically meaningful, with lower body exercises showing greater benefit than upper body.
Effect of citrulline on post-exercise rating of perceived exertion, muscle soreness, and blood lactate levels: A systematic review and meta-analysis
Hye Chang Rhim, Sung Jong Kim, Jewel Park et al.
Journal of Sport and Health Science
Across 13 RCTs (206 participants), citrulline supplementation significantly reduced post-exercise RPE and muscle soreness at 24 h and 48 h post-exercise, with no significant effect on blood lactate. Most common dose was 8 g citrulline malate. Benefits for soreness diminished by 72 h.
Therapeutic potential of citrulline as an arginine supplement: a clinical pharmacology review
Jahidur Rashid, Shaun S Kumar, Kathleen M Job et al.
Paediatric Drugs
L-citrulline demonstrates superior bioavailability over L-arginine by bypassing hepatic first-pass metabolism. Review concludes citrulline shows promise for improving NO regulation in cardiovascular disease, but optimal clinical use in paediatrics requires better-defined pharmacokinetic-pharmacodynamic relationships across developmental stages.
Effects of Citrulline Supplementation on Exercise Performance in Humans: A Review of the Current Literature
Adam M Gonzalez, Eric T Trexler
Journal of Strength and Conditioning Research
Systematic review found that L-citrulline supplementation increases plasma citrulline, arginine, and nitrate concentrations, and can enhance exercise performance and recovery. However, evidence for improved vasodilation was described as scarce and inconsistent. Investigators concluded net performance benefit exists but further research is required.
Effect of L-Citrulline Supplementation on Blood Pressure: a Systematic Review and Meta-Analysis of Clinical Trials
Mohammad Sadegh Mirenayat, Sajjad Moradi, Hamed Mohammadi et al.
Current Hypertension Reports
Meta-analysis of 5 interventions found that L-citrulline supplementation had no statistically significant effect on either brachial or aortic systolic or diastolic blood pressure. Body weight status was identified as a source of heterogeneity. Earlier evidence did not support citrulline for blood pressure reduction in general populations.
l-Citrulline Supplementation: Impact on Cardiometabolic Health
Timothy D Allerton, David N Proctor, Jacqueline M Stephens et al.
Nutrients
Narrative review concludes that oral L-citrulline consistently increases plasma L-arginine and NO bioavailability more effectively than oral L-arginine supplementation (which is largely neutralised by first-pass metabolism). Evidence supports BP-lowering potential in pre-hypertensive and hypertensive populations, and preliminary metabolic and muscle health benefits in older adults.
Oral L-citrulline supplementation improves erection hardness in men with mild erectile dysfunction
Luigi Cormio, Mario De Siati, Fabrizio Lorusso et al.
Urology
Single-blind RCT (24 men, 1.5 g/day L-citrulline vs placebo) found 50% of citrulline-treated men improved erection hardness scores vs 8.3% on placebo. Well-tolerated with no adverse events. While less potent than PDE5 inhibitors, L-citrulline represents a safe alternative for mild erectile dysfunction via the L-arginine/NO pathway.