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Head-to-head evidence comparison — which supplement is right for you?
L-Citrulline wins 2 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Mostly mechanism / observational
2 of 2 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
9 of 11 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Glycerol and L-Citrulline have evidence — compare verdict strength side-by-side.
1-1.5g per kg body weight
1-2.5 hours before endurance exercise, Consume with large volume of fluid (1-2L)
Glycerol powder (65% concentration typical)
3-6g (or 6-8g citrulline malate)
30-60 minutes before exercise, Or split doses throughout day
L-Citrulline powder (pure form)
During exercise (1-3 hours post-ingestion)
During exercise in heat
During exercise
1-2 hours post-ingestion
1-2 weeks
24-48 hours post-exercise
30-60 minutes
With doses >10g
Nutritional Ergogenic Aids in Combat Sports: A Systematic Review and Meta-Analysis
Nutrients (2022) · Meta analysis
In this regard, abilities including the number of attacks, reaction time, handgrip strength, power and TTE, among others, were improved.
The effect of pre-exercise oral hyperhydration on endurance exercise performance, heart rate, and thermoregulation: a meta-analytical review
Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme (2024) · Meta analysis
Meta-analysis determined overall effect size (Hedges' g), and meta-regression the influence of independent moderators (ambient temperature, hyperhydration agent, exercise mode, extent of hyperhydration).
Meta-analysis: Effects of glycerol administration on plasma volume, haemoglobin, and haematocrit
Drug testing and analysis (2013) · Meta analysis
The meta-analysis revealed that the increase in plasma volume was 3.3% larger (95%-CI: 1.1-5.5%) after glycerol administration when compared to fluid only.
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).
Based on meta-analysis showing hyperhydration effects on endurance. Conservative effectiveness given limited direct glycerol performance studies in the provided evidence. GI side effects increase notably at higher doses.
Meta-analysis showed significant reduction in muscle soreness 24h post-exercise but effect size was modest. Studies primarily used citrulline malate form.
AI-estimated from published studies. Interpret as directional guidance.
L-Citrulline has a higher evidence score (6/10 vs 5.8/10) and wins in 2 of 3 categories.
For improve endurance, L-Citrulline has a higher relevance score (85 vs 80).
No known interactions between Glycerol and L-Citrulline have been documented in our database. However, always consult a healthcare provider before combining supplements.