Compound or practice · Supplement
Creatine
The most-studied performance supplement in existence — and it quietly helps brains too.
- Overall grade
- Grade A
- Last revised
- 5
- graded outcomes
- 3
- references listed
A hand-written entry in Prometheus's bundled library. Its grades are the entry's own reading of the evidence, not a peer-reviewed review.
2 at grade A · 4 at grade B · 3 at grade C — 9 graded rows
What is known
Each outcome with its grade (how strong the evidence is, A to D), the size of the effect where the entry records one, and how often studies agree.
- Strength / power outputEvidence grade A
~5–10% rep improvement at fixed load; hundreds of RCTs
Moderatehigh
- Lean mass (with training)Evidence grade A
+1–2kg over 8–12 weeks vs placebo
Moderatehigh
- Working memoryEvidence grade B
Strongest in vegetarians and under sleep deprivation
Smallmixed
- Sprint performanceEvidence grade B
Repeated-sprint > single-sprint benefit
Smallmixed
- Bone densityEvidence grade C
Early trials in older adults, needs replication
Unclearlow
Conditions
How the entry reads its effect on diagnosed conditions: the direction first, then the grade. Never a substitute for the person who treats you.
- Sarcopenia (age-related muscle loss) ImprovesEvidence grade BWith resistance training in older adults — the ISSN-endorsed clinical use caseGrade B
- Depression May improveEvidence grade CAdjunct RCTs show faster SSRI response; small samples so farGrade C
- Type 2 diabetes May improveEvidence grade CModestly better glycemic control when paired with trainingGrade C
- Chronic kidney disease No clear effectEvidence grade BRaises the creatinine lab without harming function — flag supplementation to your nephrologistGrade B
What is uncertain
Read off the same rows as above. Nothing here is added that the entry does not itself record.
- Thin evidence: Bone density (grade C).
- Studies disagree: Working memory (mixed agreement); Sprint performance (mixed agreement).
- Watch with Caffeine + L-Theanine: A thin, contradictory literature on caffeine blunting the ergogenic effect — likely fine at normal doses
Up: % saturated. Across: weeks. No loading phase needed — stores saturate in about a month either way.
Up: % of max effect. Across: g/day. 5g captures nearly all of it; more mostly costs money.
The evidence in words
What it is
Creatine is a phosphate shuttle: it regenerates ATP during short, hard efforts. Your body makes ~1g/day and diet adds a little more; supplementation saturates muscle stores about 20–40% above baseline. Monohydrate is the reference form — no other form has beaten it in a head-to-head trial.
What the evidence shows
Across 300+ trials the strength signal is unambiguous: ~5–10% more reps at a given load and 1–2kg extra lean mass over a training block, mostly water in the first weeks, then real tissue. The newer, smaller literature on cognition points to modest working-memory and fatigue-resistance benefits, strongest under sleep deprivation and in vegetarians.
What to expect
Weeks 1–2: scale up 0.5–1.5kg (intracellular water — this is storage, not bloat). Weeks 3–8: extra rep or two on repeated sets. Cognition effects, if any, are subtle — measure with a consistent task, not vibes. Non-responders exist (~20–30%, high baseline stores).
How it is used
As the entry records it, from the studies it summarises. Not a recommendation for you — doses that suit a trial population may not suit you.
- Standard
- 5g monohydrate daily, any time — consistency beats timing. No loading needed; stores saturate in ~3–4 weeks.
- Fast saturation
- 20g/day split ×5–7 days, then 5g/day. Only worth it before a near-term event.
- Hydration
- Drink to thirst; the water shift is intracellular, not dehydrating.
Goes with
- Protein intakeAdditive lean-mass effects in the same training blockEvidence grade A
Questions people ask
Does it damage kidneys?
No signal in healthy kidneys across decades of trials — the myth comes from creatinine (a breakdown product) inflating a lab marker doctors use to estimate kidney function. Flag supplementation before bloodwork.
Cycle it?
No physiological reason to. Stores simply return to baseline ~4 weeks after stopping.
Caffeine conflict?
The interaction literature is thin and contradictory; in practice nobody has shown a meaningful blunting at normal doses.
Related reading
Entries that share this one's tags or conditions.
- Noopept for CognitionEvidence grade D — Limited Western dataEvidence grade D
- Oxiracetam for CognitionEvidence grade D — SparseEvidence grade D
- Panax Ginseng for CognitionEvidence grade C — InconsistentEvidence grade C
- Omega-3 (EPA/DHA)Triglyceride-lowering is bankable; everything else scales with your baseline fish intake.Evidence grade A
Sources
As this entry records them: title, journal and year. None carries a DOI or PubMed id, so none is linked as a verified paper. Each link searches PubMed for the title; check that what you find is what the entry describes.
- 1.ISSN position stand: creatine supplementation in exercise — J Int Soc Sports Nutr, 2017. Search PubMed (opens in a new tab)
- 2.Creatine and cognitive performance: systematic review — Exp Gerontol, 2018. Search PubMed (opens in a new tab)
- 3.Common questions and misconceptions about creatine — J Int Soc Sports Nutr, 2021. Search PubMed (opens in a new tab)
Last revised . A grade is this entry's reading of the evidence, not medical advice.