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Head-to-head evidence comparison — which supplement is right for you?
Acetyl-L-Carnitine and Caffeine are closely matched across evidence, studies, and safety.
Verdict
Likely helps
8 of 11 studies with measurable effects showed benefit.
Top outcomes
Verdict
Likely helps
22 of 25 studies with measurable effects showed benefit.
Top outcomes
Shared outcomes (1)
Outcomes where both Acetyl-L-Carnitine and Caffeine have evidence — compare verdict strength side-by-side.
500-2000mg
Morning or early afternoon, With or without food
ALCAR powder or capsules
100-200mg
Morning, 30-60 minutes before exercise
Pill/capsule for precise dosing
1-4 weeks
4-12 weeks
2-4 weeks
15-45 minutes
30-60 minutes
30-60 minutes
30-60 minutes
Acetyl-L-carnitine for the treatment of diabetic peripheral neuropathy
The Cochrane database of systematic reviews (2019) · Meta analysis · n=907
The risk of bias was high in both trials of different ALC doses and low in the other two trials.No included trial measured the proportion of participants with at least moderate (30%) or substantial (50%) pain relief.
Impact of Dietary Supplements on Clinical Outcomes and Quality of Life in Patients with Breast Cancer: A Systematic Review
Nutrients (2025) · Systematic review · n=45
Curcumin studies presented mixed results.
Effects of Carnitine and Coenzyme Q10 on Sperm Quality and Pregnancy Rates in Men with Unexplained Infertility: A Systematic Review and Network Meta-Analysis
Reproductive sciences (Thousand Oaks, Calif.) (2025) · Meta analysis
L-carnitine, coenzyme Q10 and L-carnitine + acetyl-L-carnitine significantly improved sperm quality parameters compared with placebo.
Effect of Acute Caffeine Intake on the Fat Oxidation Rate during Exercise: A Systematic Review and Meta-Analysis
Nutrients (2020) · Meta analysis · n=2020
A subsequent meta-analysis was performed using the random effects model to calculate the standardized mean difference (SMD).
The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials
Critical reviews in food science and nutrition (2019) · Meta analysis · n=606
Thirteen RCTs with 606 participants were included in the meta-analyses.
Effect of Caffeine and Nitrates Combination on Exercise Performance, Heart Rate and Oxygen Uptake: A Systematic Review and Meta-Analysis
Nutrients (2024) · Meta analysis · n=95
The meta-analysis revealed that caffeine and nitrates supplementation (CAF+nitrates) did not enhance performance in time trials (TTs) over the CAF alone (g = -0.06; 95% CI = -0.46 to 0.35; p = 0.78) or nitrates alone (g = 0.29; 95% CI = -0.12 to 0.70; p = 0.17).
Based on meta-analysis of 523 participants showing moderate effect (VAS reduction 1.20 points). High risk of bias noted in some trials. Effect size is conservative given study limitations.
Based on multiple meta-analyses showing 3-6mg/kg optimal dosing. Performance benefits plateau around 200-300mg with increased jitteriness at higher doses.
AI-estimated from published studies. Interpret as directional guidance.
Both Acetyl-L-Carnitine and Caffeine are closely matched — the best choice depends on your specific health goals.
For boost daily energy, Caffeine has a higher relevance score (98 vs 70).
No known interactions between Acetyl-L-Carnitine and Caffeine have been documented in our database. However, always consult a healthcare provider before combining supplements.