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Lci6.0
L-Citrulline Research
Likely helps
163 peer-reviewed studies
What the evidence says
Likely helps
L-Citrulline appears to help in 8 of 10 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1991–2026 with a typical study size of 25 participants.
Based on 163 studies · 15 meta-analyses · 125 RCTs · 888,143 total participants
Confidence
High confidence
What the studies found
8helped2unclear· 153 more without graded effect data
By outcome
Heart & blood pressureReduces blood pressure via sustained nitric oxide production · 4-8 weeks
Likely helps110 studies
Endurance & exercise performanceImproved endurance and reduced fatigue · 1-2 weeks consistent use · Increases NO availability and exercise tolerance · 30-60 minutes
RecoveryUp to 40% reduction in muscle soreness · 24-48 hours post-exercise
Mostly mechanism / observational15 studies
Lean body mass & muscle growthMay improve high-rep performance · 1-2 weeks
Mostly mechanism / observational9 studies
Glucose & metabolic
Mostly mechanism / observational8 studies
Therapeutic & clinical
Mostly mechanism / observational8 studies
Weight management
Mostly mechanism / observational7 studies
Cholesterol & lipidsReduces blood pressure via sustained nitric oxide production · 4-8 weeks
Mostly mechanism / observational3 studies
Safety profile
Mostly mechanism / observational3 studies
Inflammation
Too few graded studies1 study
Men's vitalityImproved erectile function via nitric oxide · 2-4 weeks
Too few graded studies1 study
By the numbers
Pulled from 30 studies with measurable effects
Likely real effects
54%
across studies
People studied
888k
typical study: 25 people
Strongest designs
140
15 pooled, 125 randomised
Showed benefit
70%
7/10 studies
How long studies ran
1–4 weeks
3
1–3 months
4
Populations Studied
Athletes/exercising individuals3
Hypertensive postmenopausal women2
Diverse populations1
Middle-aged and elderly individuals1
Active research area
76 studies in the last 5 years · Latest meta-analysis: 2026
199120082026
1Oxidative stress after exerciseMeta-Analysisn=1,080 · large study2023
In plain English: In conclusion, our systematic review and meta-analysis found that L-Citrulline and L-Arginine did not influence inflammatory biomarkers and oxidative stress after exercise.
Porto AA et al. · Nutrients (2023)
No clear effect
← WorseNo effectBetter →
Could be chance
We observed no difference between pre- vs. post-exercise for oxidative stress (subtotal = -0.21 [CI: -0.56, 0.14], p = 0.24, and heterogeneity = 0%.
In the sub-group "L-Arginine" we found a subtotal = -0.29 [-0.71, 0.12], p = 0.16, and heterogeneity = 0%.
No differences were observed between groups (p = 0.47), and I² = 0%) or in antioxidant activity (subtotal = -0.28 [-1.65, 1.08], p = 0.68, and heterogeneity = 0%).
3Systolic blood pressureMeta-Analysisn=415 · medium study2025
In plain English: l-citrulline supplementation and watermelon intake overall lowered BP in middle-aged and elderly individuals.
Luo P et al. · Clinical nutrition ESPEN (2025)
Noticeable benefit
← WorseNo effectBetter →
Likely real
The results indicate that l-citrulline supplementation and watermelon intake significantly reduced SBP (-4.02 mmHg [95 % CI: -6.54 to -1.50], P = 0.002) and DBP (-2.54 mmHg [95 % CI: -4.27 to -0.81], P = 0.004) in the elderly.
Subgroup analysis showed that the combined supplementation of l-citrulline and l-arginine significantly decreased SBP (-10.44 mmHg [95 % CI: -13.57 to -7.31], P < 0.00001) and DBP (-4.86 mmHg [95 % CI: -7.93 to -1.79], P = 0.002) in this population.
l-citrulline supplementation and watermelon intake overall lowered BP in middle-aged and elderly individuals.
In plain English: CIT supplementation appears to have no overall effect on body composition.
Ashtary-Larky D et al. · Nutrients (2025)
Overall, CIT supplementation had no substantial effects on body mass index (BMI), body weight, fat mass (FM), waist circumference (WC), body fat percentage (BFP), and fat-free mass (FFM).
Interventions lasting 3 to 8 weeks were associated with a significant increase in FFM.
CIT supplementation appears to have no overall effect on body composition.
12Post-exercise rating of perceived exertionMeta-Analysisn=206 · medium study2020
In plain English: Citrulline supplements significantly reduced post-exercise RPE and muscle soreness without affecting blood lactate levels.
Rhim HC et al. · Journal of sport and health science (2020)
Likely real
Citrulline supplementation significantly reduced RPE (n = 7, p = 0.03) and muscle soreness 24-h and 48-h after post-exercise (n = 7, p = 0.04; n = 6, p = 0.25, respectively).
However, citrulline supplementation did not significantly reduce muscle soreness 72-h post-exercise (n = 4, p = 0.62) or lower blood lactate levels (n = 8, p = 0.17).
In plain English: Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent.
d'Unienville NMA et al. · Journal of the International Society of Sports Nutrition (2021)
Barely noticeable benefit
← WorseNo effectBetter →
Could be chance
No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24).
Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent.
Highly trained endurance athletes do not appear to benefit from consuming nitrate-rich foods but may benefit from polyphenol consumption.
In plain English: The present systematic review and meta-analysis suggests that L-citrulline supplementation had no beneficial effect on blood pressure.
Mirenayat MS et al. · Current hypertension reports (2018)
In plain English: Given the positive effects observed from some investigations, future studies should continue to investigate the effects of both acute and chronic supplementation with L-citrulline and citrulline malate on markers of blood flow and exercise performance and should seek to elucidate the mechanism underlying such effects.
Gonzalez AM et al. · Journal of strength and conditioning research (2020)
Oral L-citrulline and citrulline malate supplementation have shown to increase plasma citrulline and arginine concentrations, along with total nitrate and nitrite concentrations.
Although blood flow enhancement is a proposed mechanism for the ergogenic potential of L-citrulline, evidence supporting acute improvements in vasodilation and skeletal muscle tissue perfusion after supplementation is scarce and inconsistent.
Nevertheless, several studies have reported that L-citrulline supplementation can enhance exercise performance and recovery.
16Physical performanceSystematic Reviewn=19 · very small study2019
In plain English: However, there is not enough evidence to establish a beneficial L-citr dosage for physical performance.
Huerta Ojeda Á et al. · Nutricion hospitalaria (2019)
All articles using a supplementation protocol with these amino acids, separately or in groups, were selected.
Results: a total of 38 articles were found, which were stratified according to the established protocol: a) supplementation with L-arg (n = 19); b) supplementation with L-arg and L-citr (n = 1); and c) supplementation with L-citr (n = 18), whether of short or prolonged duration.
Conclusion: there is evidence that L-citr works better as ergogenic than L-arg does on physical performance, since L-citr showed a positive effect on the rate of perceived exertion and muscular pain, in addition to a decrease in lactate concentrations and time in maximum tests.
In plain English: The generation of endogenous NO then causes positive biochemical, hemodynamic, and vascular effects, remodeling the physio-pathological conditions of those adults that present risk factors for cardiovascular diseases.
Baião DDS, da Silva DVT, Paschoalin VMF. · Nutrients (2025)
By enhancing circulating L-arginine, L-citrulline indirectly improves the synthesis and bioavailability of nitric oxide, promoting smooth muscle vasodilation.
The beneficial effects of oral L-citrulline ingestion through watermelon require additional evidence, but it has already been demonstrated that it does not undergo hepatic metabolism, instead being transported to the kidneys to participate in de novo L-arginine synthesis.
The generation of endogenous NO then causes positive biochemical, hemodynamic, and vascular effects, remodeling the physio-pathological conditions of those adults that present risk factors for cardiovascular diseases.
18pre-eclampsia preventionMeta-Analysisn=2,028 · very large study2025
In plain English: More trials are needed to determine the optimal dose and time to commence supplementation and support clinical decision-making.
Makama M, McDougall ARA, Cao J, Mills K, Nguyen PY, Hastie R, Ammerdorffer A, Gülmezoglu AM, Vogel JP. · BJOG : an international journal of obstetrics and gynaecology (2025)
Large benefit
← WorseNo effectBetter →
In prevention trials, L-arginine was associated with a reduced risk of pre-eclampsia (relative risk [RR] 0.52; 95% confidence interval [CI], 0.35, 0.78; low-certainty evidence, four trials) and severe pre-eclampsia (RR 0.23; 95% CI, 0.09, 0.55; low-certainty evidence, three trials).
In treatment trials, L-arginine may reduce mean systolic blood pressure (MD -5.64 mmHg; 95% CI, -10.66, -0.62; very low-certainty evidence, three trials) and fetal growth restriction (RR 0.46; 95% CI, 0.26, 0.81; low-certainty evidence, two trials).
Only one study (36 women) examined L-citrulline and reported no effect on pre-eclampsia or blood pressure.