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Head-to-head evidence comparison — which supplement is right for you?
L-Glutamine wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
8 of 10 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
3 of 3 studies with measurable effects showed benefit.
Top outcomes
3-6g (or 6-8g citrulline malate)
30-60 minutes before exercise, Or split doses throughout day
L-Citrulline powder (pure form)
5-10g
Post-workout, Before bed, Or split throughout day
L-Glutamine powder
1-2 weeks
24-48 hours post-exercise
30-60 minutes
With doses >10g
2-4 weeks
2-4 weeks
1-2 weeks
Absence of Effects of L-Arginine and L-Citrulline on Inflammatory Biomarkers and Oxidative Stress in Response to Physical Exercise: A Systematic Review with Meta-Analysis
Nutrients (2023) · Meta analysis · n=1080
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%.
Effects of Citrulline or Watermelon Supplementation on Body Composition: A Systematic Review and Dose-Response Meta-Analysis
Nutrients (2025) · Meta analysis
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).
Effect of food sources of nitrate, polyphenols, L-arginine and L-citrulline on endurance exercise performance: a systematic review and meta-analysis of randomised controlled trials
Journal of the International Society of Sports Nutrition (2021) · Meta analysis
No effect on exercise performance following consumption of foods rich in L-citrulline was identified (SMD=-0.03, p=0.24).
A Phase 3 Trial of l-Glutamine in Sickle Cell Disease
The New England journal of medicine (2018) · Rct · n=230
A total of 230 patients (age range, 5 to 58 years; 53.9% female) were randomly assigned, in a 2:1 ratio, to receive l-glutamine (152 patients) or placebo (78 patients).
What Is the Role of Nutritional Supplements in Support of Total Hip Replacement and Total Knee Replacement Surgeries? A Systematic Review
Nutrients (2018) · Systematic review
Amino acid supplementation is reported to reduce muscle atrophy and accelerate return of functional mobility.
Evidence and gaps in clinical outcomes of novel pharmacologic therapies for sickle cell disease: A systematic literature review highlighting insights from clinical trials and real-world studies
Blood reviews (2025) · Systematic review · n=97
A pivotal phase III study of l-glutamine showed that patients treated with l-glutamine had a 25 % reduction in pain crises and 33 % fewer hospital days compared to placebo. l-glutamine was generally well tolerated with minimal side effects.
Meta-analysis showed significant reduction in muscle soreness 24h post-exercise but effect size was modest. Studies primarily used citrulline malate form.
Based on RCT showing reduced URTI incidence in combat athletes (n=21) and enhanced IgA levels. Limited sample size and specific population studied. Effect may be primarily in high-stress/training conditions.
AI-estimated from published studies. Interpret as directional guidance.
L-Glutamine has a higher evidence score (9/10 vs 9/10) and wins in 2 of 3 categories.
For speed up recovery, L-Citrulline has a higher relevance score (80 vs 65).
No known interactions between L-Citrulline and L-Glutamine have been documented in our database. However, always consult a healthcare provider before combining supplements.