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Head-to-head evidence comparison — which supplement is right for you?
Whey Protein 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
19 of 22 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both L-Citrulline and Whey Protein have evidence — compare verdict strength side-by-side.
3-6g (or 6-8g citrulline malate)
30-60 minutes before exercise, Or split doses throughout day
L-Citrulline powder (pure form)
20-40g per serving
Post-workout (within 2 hours), Morning, Between meals
Whey Protein Isolate
1-2 weeks
24-48 hours post-exercise
30-60 minutes
With doses >10g
4-8 weeks
24-48 hours post-workout
Immediate
Within hours of consumption
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).
Comparative Efficacy of Different Protein Supplements on Muscle Mass, Strength, and Physical Indices of Sarcopenia among Community-Dwelling, Hospitalized or Institutionalized Older Adults Undergoing Resistance Training: A Network Meta-Analysis of Randomized Controlled Trials
Nutrients (2024) · Meta analysis · n=5272
Treatment effects for main outcomes were expressed as standard mean difference (SMD) with 95% confidence interval (CI).
Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis
Nutrients (2023) · Meta analysis · n=637
However, appendicular muscle mass significantly improved in the experimental group compared to the control group.
A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength
British Journal of Sports Medicine (2018) · Meta analysis · n=1863
Protein supplementation increases muscle mass gains
Meta-analysis showed significant reduction in muscle soreness 24h post-exercise but effect size was modest. Studies primarily used citrulline malate form.
Based on multiple meta-analyses with >3000 participants. Effects require concurrent resistance training. Benefits plateau around 30-40g per serving. Isolate forms may reduce digestive issues.
AI-estimated from published studies. Interpret as directional guidance.
Whey Protein has a higher evidence score (9/10 vs 9/10) and wins in 2 of 3 categories.
For build strength & muscle, Whey Protein has a higher relevance score (95 vs 70).
No known interactions between L-Citrulline and Whey Protein have been documented in our database. However, always consult a healthcare provider before combining supplements.