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Head-to-head evidence comparison — which supplement is right for you?
Collagen wins 1 of 3 categories. Both are solid choices — the best pick depends on your specific goals.
Verdict
Likely helps
6 of 6 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
8 of 10 studies with measurable effects showed benefit.
Top outcomes
10-15g
Any time of day, With vitamin C for enhanced synthesis
Hydrolyzed collagen peptides (powder)
3-6g (or 6-8g citrulline malate)
30-60 minutes before exercise, Or split doses throughout day
L-Citrulline powder (pure form)
8-12 weeks
8-12 weeks
12 weeks
First week
1-2 weeks
24-48 hours post-exercise
30-60 minutes
With doses >10g
Effects of Collagen Supplements on Skin Aging: A Systematic Review and Meta-Analysis
The American Journal of Medicine (2025) · Meta analysis · n=1474
23 RCTs with 1474 participants
Effect of collagen supplementation on knee osteoarthritis: an updated systematic review and meta-analysis of randomised controlled trials
Clinical and experimental rheumatology (2025) · Meta analysis · n=870
The meta-analysis revealed an overall significant improvement of both function [MD, -6.46 (95% CI -9.52, -3.40); I2=75%; p=0.00001] and pain scores [MD, -13.63 (95% CI -20.67, -6.58); I2=88%; p=0.00001], favouring collagen supplementation.
Impact of Collagen Peptide Supplementation in Combination with Long-Term Physical Training on Strength, Musculotendinous Remodeling, Functional Recovery, and Body Composition in Healthy Adults: A Systematic Review with Meta-analysis
Sports medicine (Auckland, N.Z.) (2024) · Meta analysis · n=768
This systematic review and meta-analysis represents the first comprehensive investigation into the effects of long-term CP supplementation combined with regular physical training on various aspects of musculoskeletal health in adults.
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).
Meta-analysis of 23 RCTs (n=1474) showed high-quality studies had less effect than industry-funded studies. Benefits include improved skin elasticity and hydration. Hydrolyzed collagen peptides preferred for bioavailability.
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.
Collagen has a higher evidence score (9/10 vs 9/10) and wins in 1 of 3 categories.
For speed up recovery, L-Citrulline has a higher relevance score (80 vs 70).
No known interactions between Collagen and L-Citrulline have been documented in our database. However, always consult a healthcare provider before combining supplements.