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🧬 Research Summaries

Supplement Research

Plain-English summaries of the RCTs and meta-analyses behind our supplement recommendations. Every finding linked to the original publication.

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Meta-Analysis Journal of Strength & Conditioning Research · 2023
Creatine Supplementation and Muscle Strength: Meta-Analysis of 22 RCTs
Creatine

A 2023 meta-analysis of 22 RCTs found creatine supplementation produced a statistically significant increase in 1-rep max strength (+8.1%, 95% CI: 5.4–10.9%) and lean mass (+1.37kg, 95% CI: 0.97–1.78kg) over 4–16 weeks compared to placebo. The magnitude of effect was consistent across training experience levels.

Key Findings
  • Creatine monohydrate at 3–5g/day produces 8.1% strength gains vs placebo over 4–16 weeks
  • No significant difference between creatine monohydrate and HCl forms at equivalent doses
  • Loading phase (20g/day for 5–7 days) reaches saturation faster but same endpoint by week 4 at 5g/day
  • Effects strongest in fast-twitch fibre-dominant movements (bench press, sprint, jump)
Evidence-based dose: 5g/day creatine monohydrate (no loading required)
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Systematic Review British Journal of Sports Medicine · 2018
Protein Supplementation and Muscle Mass: Systematic Review of 49 RCTs
Whey ProteinProtein

A landmark 2018 BJSM meta-analysis (Morton et al.) of 49 RCTs involving 1,863 participants found protein supplementation significantly augmented muscle mass and strength gains during resistance training. Effect size was moderate and consistent. The benefits of protein supplementation plateaued at approximately 1.62g/kg/day — additional protein above this threshold provided no further muscle-building benefit.

Key Findings
  • Protein supplementation increased lean mass by 0.69kg more than placebo over median 13 weeks
  • Plateau at ~1.62g protein/kg/day — no additional benefit from higher intakes for most
  • No significant difference in outcomes between protein sources at matched leucine doses
  • Younger individuals responded more strongly to supplementation than older adults (diminishing response after 40)
Evidence-based dose: 1.6–2.2g protein/kg/day total (supplement fills the dietary gap)
Read ON Gold Standard Whey Review →
RCT Indian Journal of Alternative Medicine · 2012
KSM-66 Ashwagandha for Stress and Cortisol: Double-Blind RCT
Ashwagandha

A 2012 double-blind, placebo-controlled RCT by Chandrasekhar et al. enrolled 64 adults with chronic stress and randomised them to 300mg KSM-66 ashwagandha twice daily or placebo for 60 days. The ashwagandha group showed a 27.9% reduction in serum cortisol and a 69% reduction in anxiety and stress scale scores vs placebo. Sleep quality also improved significantly.

Key Findings
  • 27.9% reduction in serum cortisol at 60 days vs placebo (p<0.001)
  • 69% reduction in perceived stress scores vs placebo (p<0.001)
  • Significant improvement in sleep onset and quality vs placebo
  • KSM-66 standardised extract (root only, 5% withanolides) used — not whole root powder
Evidence-based dose: 300mg KSM-66 twice daily (600mg total)
Ashwagandha Ingredient Guide →
RCT Journal of Strength & Conditioning Research · 2010
Citrulline Malate Enhances Athletic Anaerobic Performance: RCT
Citrulline

A 2010 crossover RCT by Pérez-Guisado and Jakeman tested 8g citrulline malate vs placebo in resistance-trained males completing barbell bench press to failure across multiple sets. The citrulline group completed 52.92% more reps (p<0.001), reported lower post-exercise muscle soreness (40% reduction), and had higher lactate levels post-exercise indicating greater total work output.

Key Findings
  • 52.92% more total repetitions to failure across sets vs placebo (p<0.001)
  • 40% reduction in muscle soreness 24–48 hours post-exercise
  • Higher blood lactate levels in citrulline group — indicating greater total anaerobic work performed
  • Effect appeared from set 2 onwards — single set performance not significantly different
Evidence-based dose: 8g citrulline malate (2:1 form), 60 min pre-workout
BULK Black Pre-Workout Review (8g Citrulline) →
Meta-Analysis Evidence Report / Technology Assessment · 2006
Melatonin Dose-Response and Sleep: Meta-Analysis of 19 RCTs
Melatonin

A comprehensive 2006 meta-analysis by Buscemi et al. analysed 19 RCTs of melatonin supplementation. Key finding: melatonin significantly reduced sleep onset latency by 7–12 minutes and improved overall sleep quality. Critically, doses above 0.5–1mg produced no additional benefit over lower doses — a finding systematically ignored by the supplement industry which sells 5–10mg products.

Key Findings
  • Melatonin reduces sleep onset latency by 7–12 minutes (meta-analytic average)
  • 0.5mg and 5mg produce equivalent sleep onset improvements — dose-response plateaus extremely early
  • Melatonin is a circadian clock signal, not a sedative — it works by signalling darkness, not inducing sleep
  • Best evidence for jet lag and circadian rhythm disorders; modest evidence for primary insomnia
Evidence-based dose: 0.5–1mg (NOT the 5–10mg doses sold commercially)
Melatonin Ingredient Guide →
Meta-Analysis Nutrients · 2020
Omega-3 Supplementation Reduces Exercise-Induced Muscle Damage: Meta-Analysis
Omega-3

A 2020 meta-analysis of 15 RCTs investigated omega-3 supplementation effects on exercise-induced muscle damage markers. EPA+DHA supplementation significantly reduced CK (creatine kinase, a muscle damage marker) by 25–35% post-exercise, reduced IL-6 (inflammatory cytokine) levels, and decreased delayed-onset muscle soreness (DOMS) ratings by approximately 20% compared to placebo.

Key Findings
  • 25–35% reduction in post-exercise CK (muscle damage marker) vs placebo
  • Significant reduction in IL-6 inflammatory cytokine post-exercise
  • ~20% reduction in DOMS severity ratings vs placebo
  • Effects required 4+ weeks of supplementation to reach significance — not acute
Evidence-based dose: 2,000–3,000mg combined EPA+DHA daily for 4+ weeks
Omega-3 Ingredient Guide →