L-Citrulline

Different mechanisms for endurance

Citrulline for blood flow, beta-alanine for acid buffering

⟡ Agmatine

Both affect nitric oxide pathways

Enhanced vasodilation and muscle pumps

⟡ Arginine

Citrulline converts to arginine in the kidneys

Sustained nitric oxide production; citrulline has better bioavailability

Top studies from 39+ peer-reviewed papers

📚meta-analysisn=1080

Porto AA et al. • Nutrients (2023)

“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.”

Key Findings:

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%).
In the "L-Arginine" sub-group, we found a subtotal = -3.90 [-14.18, 6.38], p = 0.46, and heterogeneity was not applicable.

📚meta-analysisn=2028

Makama M et al. • BJOG : an international journal of obstetrics and gynaecology (2025)

“L-arginine may be promising for pre-eclampsia prevention and treatment, but findings should be interpreted cautiously.”

Key Findings:

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).
L-arginine may be promising for pre-eclampsia prevention and treatment, but findings should be interpreted cautiously.
More trials are needed to determine the optimal dose and time to commence supplementation and support clinical decision-making.

📚meta-analysis

Ashtary-Larky D et al. • Nutrients (2025)

“CIT supplementation appears to have no overall effect on body composition.”

Key Findings:

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.
However, exploratory findings indicated potential benefits at higher doses or shorter durations.

📊rctn=115

Winer N et al. • The American journal of clinical nutrition (2025)

“The current trial found no benefit of oral L-citrulline supplementation to females with PE regarding either the duration of pregnancy, fetal growth, or maternal and neonatal outcomes.”

Key Findings:

The duration of pregnancy between inclusion and delivery was unaltered (hazard ratio: 0.90; 95% confidence interval: 0.62, 1.31).
Liver enzymes were higher on the day of delivery in the treated, compared to the placebo group (65.1 compared with 33.2 UI and 70.4 compared with 33.7 UI for alanine aminotransferase and aspartate aminotransferase, respectively, (estimate: 5.92; 95% confidence interval: 1.09, 10.74).
Systolic blood pressure (BP) was higher at delivery in the citrulline group compared with the control group (P = 0.015), whereas the diastolic BP showed no difference.

📚meta-analysis

Compare with Others Find Based on Your Goals

d'Unienville NMA et al. • Journal of the International Society of Sports Nutrition (2021)

“Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent.”

Key Findings:

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.
Further research into food sources, dosage and supplementation duration to optimise the ergogenic response to polyphenol consumption is warranted.

View all 39+ studies

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L-Citrulline

amino acid

L-Citrulline

Amino acid that boosts nitric oxide production, improving blood flow, exercise performance, and recovery.

performancerecoverynitric oxidepumpblood flowendurance

39+ studies

Evidence

Reviewed 19 days ago

moderate

Safety

3-6g (or 6-8g citrulline malate)

Dose

1-2 weeks

Time to Effect

L-Citrulline powder (pure form)

Best Form

Mechanisms of Action

💨

Nitric Oxide Production

Increases blood vessel dilation for better blood flow

🔄

Ammonia Clearance

Helps remove exercise-induced ammonia buildup

⚡

ATP Production

May support cellular energy during exercise

Biological PathwayBeta

How L-Citrulline works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.

Supplement

Molecular Target

Biological Process

Health Outcome

Strong

Moderate

Emerging

strong

moderate

emerging

Tap node to isolate • Pinch to zoom • Tap edge for research

Recommended Dose

3-6g (or 6-8g citrulline malate)

3g10g

Optimal Timing

30-60 minutes before exercise
Or split doses throughout day

Can be taken without food

Available Forms

Form	Type
🧪L-Citrulline powder (pure form)	Recommended
💊Citrulline Malate (2:1 ratio)	Alternative
💊Capsules	Alternative

Pure L-citrulline is more concentrated. Citrulline malate includes malic acid which may have additional benefits for energy production.

Duration

Minimum: 1 weeks

Optimal: 2 weeks

Cycling: Not required

Note: Can be taken on empty stomach. For chronic benefits, daily dosing is more important than timing. Citrulline malate is ~56% citrulline by weight.

🏃

Improved Endurance

Better performance in prolonged exercise

⏱️ 1-2 weeks

75% of users notice thispositive

💪

Reduced Muscle Soreness

Less DOMS after intense training

📅 24-48 hours post-exercise

70% of users notice thispositive

🔥

Enhanced Muscle Pump

Better blood flow during resistance training

📅 30-60 minutes

80% of users notice thispositive

🤢

GI Discomfort

Some experience stomach issues at high doses

📅 With doses >10g

15% of users notice thistrade-off

ModerateMax safe dose: 10g/day shown safe in studies

🔴

Pregnant/nursing

Insufficient data; avoid supplementation

🟡

Heart conditions

Consult doctor due to effects on blood pressure

Who Should NOT Take This

Those taking nitrates or PDE5 inhibitors (Viagra, Cialis)
Low blood pressure

Drug Interactions

Nitrates (nitroglycerin)severe

Combined effect may cause dangerous drop in blood pressure

PDE5 inhibitors (Viagra, Cialis)moderate

May enhance blood pressure lowering effects

Blood pressure medicationsmild

May have additive blood pressure lowering effects

Possible Side Effects

Stomach discomfort

milduncommon

Tip: Take with food or reduce dose

Diarrhea

mildrare

Tip: Reduce dose

Warnings

Avoid combining with medications that lower blood pressure
Start with lower doses to assess tolerance

✦ Beetroot/Nitrates

enhances

Both boost nitric oxide through different pathways

Maximized nitric oxide production and blood flow

⟡ Beta-Alanine

Different mechanisms for endurance

Citrulline for blood flow, beta-alanine for acid buffering

⟡ Agmatine

Both affect nitric oxide pathways

Enhanced vasodilation and muscle pumps

⟡ Arginine

Citrulline converts to arginine in the kidneys

Sustained nitric oxide production; citrulline has better bioavailability

Top studies from 39+ peer-reviewed papers

📚meta-analysisn=1080

Porto AA et al. • Nutrients (2023)

“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.”

Key Findings:

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%).
In the "L-Arginine" sub-group, we found a subtotal = -3.90 [-14.18, 6.38], p = 0.46, and heterogeneity was not applicable.

📚meta-analysisn=2028

Makama M et al. • BJOG : an international journal of obstetrics and gynaecology (2025)

“L-arginine may be promising for pre-eclampsia prevention and treatment, but findings should be interpreted cautiously.”

Key Findings:

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).
L-arginine may be promising for pre-eclampsia prevention and treatment, but findings should be interpreted cautiously.
More trials are needed to determine the optimal dose and time to commence supplementation and support clinical decision-making.

📚meta-analysis

Ashtary-Larky D et al. • Nutrients (2025)

“CIT supplementation appears to have no overall effect on body composition.”

Key Findings:

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.
However, exploratory findings indicated potential benefits at higher doses or shorter durations.

📊rctn=115

Winer N et al. • The American journal of clinical nutrition (2025)

“The current trial found no benefit of oral L-citrulline supplementation to females with PE regarding either the duration of pregnancy, fetal growth, or maternal and neonatal outcomes.”

Key Findings:

The duration of pregnancy between inclusion and delivery was unaltered (hazard ratio: 0.90; 95% confidence interval: 0.62, 1.31).
Liver enzymes were higher on the day of delivery in the treated, compared to the placebo group (65.1 compared with 33.2 UI and 70.4 compared with 33.7 UI for alanine aminotransferase and aspartate aminotransferase, respectively, (estimate: 5.92; 95% confidence interval: 1.09, 10.74).
Systolic blood pressure (BP) was higher at delivery in the citrulline group compared with the control group (P = 0.015), whereas the diastolic BP showed no difference.

📚meta-analysis

Compare with Others Find Based on Your Goals

d'Unienville NMA et al. • Journal of the International Society of Sports Nutrition (2021)

“Foods rich in polyphenols and nitrate provide trivial benefits for endurance exercise performance, although these effects may be food dependent.”

Key Findings:

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.
Further research into food sources, dosage and supplementation duration to optimise the ergogenic response to polyphenol consumption is warranted.

View all 39+ studies

What would you like to do next?

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Citrulline Malate

7.5/10

Combines citrulline for nitric oxide production with malic acid for ATP synthesis — reduces fatigue and enhances exercise endurance.

Ct9.5

Creatine

9.5/10

Increases phosphocreatine stores for faster ATP regeneration, boosting strength, power output, and cognitive function under stress.

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BCAAs