Creatine monohydrate: 30 years of evidence and the cognitive question

Key takeaways

• The 2017 International Society of Sports Nutrition (ISSN) position stand on creatine concluded creatine monohydrate is the most effective ergogenic nutritional supplement for high-intensity exercise capacity and lean body mass during training, with a strong safety record .
• Forbes et al. 2021 meta-analysis in older adults (Nutrients) reported that creatine ingestion strategies combined with resistance training improved lean tissue mass and strength versus resistance training alone .
• Cognitive effects are newer and more heterogeneous. The Sandkühler 2023 BMC Medicine randomized controlled trial in 123 healthy adults at 5 grams per day for 6 weeks found Bayesian evidence supporting a small beneficial effect of creatine on cognition, with mixed results across the cognitive tasks tested .
• The standard maintenance dose is 3 to 5 grams per day. A 20 grams per day for 5 to 7 days loading phase saturates muscle stores faster but is not required.
• Renal-function trials in healthy adults consistently show no clinically meaningful effect on creatinine clearance or measured GFR; the apparent serum creatinine rise is non-renal and reflects increased substrate availability .
• The hair-loss concern rests on a single 2009 rugby-player trial showing increased serum DHT; no follow-up trial has reproduced the finding and the original did not measure hair density .

What creatine actually does

Creatine is a nitrogenous compound synthesized from glycine, arginine, and methionine, primarily in the liver and kidneys. The body stores most of its creatine pool in skeletal muscle as phosphocreatine, which donates a phosphate to ADP to regenerate ATP during short, high-intensity efforts. Saturating the muscle creatine pool with supplementation increases the buffer of high-energy phosphate available for repeated 1- to 10-second efforts.

Practically, this translates into an extra rep or two on the heavy sets, faster repeated-sprint capacity, and greater training volume accumulated over weeks. The hypertrophy benefit is downstream of training-volume gain plus a small osmotic effect (creatine pulls water into muscle cells). It is not anabolic in the steroid sense; the effect is on substrate availability, not direct receptor agonism.

The strength and hypertrophy evidence

The performance evidence is voluminous and consistent. Buford et al. 2007 and the 2017 ISSN position stand both concluded creatine reliably increases performance on short, high-intensity tasks (1RM strength, repeated sprint, jump height) and lean mass when combined with resistance training . The Cooke et al. trials in resistance-trained men found creatine reduced muscle damage markers (creatine kinase, lactate dehydrogenase) and accelerated strength recovery after eccentric exercise.

Forbes et al. 2021 meta-analysis in Nutrients specifically examined ingestion strategies in older adults and reported that creatine plus resistance training produced significant improvements in lean tissue mass and strength relative to resistance training alone, with a roughly 1.1 kg lean-mass advantage on pooled estimates. Effect sizes were modest but consistent. Earlier general-population creatine and resistance-training trials had reported similar small-to-moderate lean-mass advantages .

Older-adult creatine trials have shown that adding creatine to a resistance-training program preserved or improved lean mass and lower-body strength versus resistance training alone (Candow and colleagues; Chilibeck et al. 2017 meta-analysis) . The aging case is mechanistically interesting because age-related declines in muscle creatine content and in resistance-training response may be partly offset by supplementation.

The cognitive evidence: smaller, newer, more heterogeneous

Brain creatine pools are smaller and turn over more slowly than muscle pools. Cognitive effects of creatine supplementation have been studied in three contexts: well-rested young adults, sleep-deprived adults, and older adults with age-related cognitive decline.

The Sandkühler 2023 BMC Medicine randomized controlled trial enrolled 123 healthy adults (vegetarians and omnivores) and administered 5 grams per day creatine or placebo for 6 weeks in a double-blind crossover design. The primary endpoints (Raven's Advanced Progressive Matrices, Backward Digit Span) did not show a statistically significant frequentist effect, but Bayesian analysis supported a small beneficial effect of creatine on cognition with mixed signals across the eight exploratory tasks tested. The trial illustrates how the cognitive-creatine literature is converging on small, task-specific signals rather than a uniform cognitive boost .

The 2024 Gordji-Nejad et al. trial in sleep-deprived adults reported a single high-dose (0.35 g per kg) creatine bolus produced acute cognitive performance and brain-energy improvements during overnight sleep deprivation . Whether this acute-bolus mechanism translates into chronic-supplementation cognitive benefits in non-sleep-deprived adults is not established.

Dosing and loading protocols

• Maintenance dose: 3 to 5 grams per day. The lower end is sufficient in smaller adults; 5 grams is the conservative default.
• Loading: optional. 20 grams per day in 4 divided doses for 5 to 7 days saturates muscle stores in 5 to 7 days versus roughly 28 days on maintenance dosing alone. Loading does not produce a larger long-run plateau, only faster saturation.
• Timing: probably does not matter. Trials testing pre-workout versus post-workout creatine timing have not produced consistent differences. The convenience of one fixed daily time tends to win in practice.
• Form: monohydrate is the most studied and least expensive form. Buffered creatine, creatine HCl, and other proprietary forms have not demonstrated superiority over monohydrate in head-to-head trials.
• Coingestion: creatine plus carbohydrate or carbohydrate plus protein increases muscle uptake versus creatine alone in radiotracer studies, but the effect on long-run training outcomes is small.

Safety profile

Creatine is one of the most-studied supplements for safety. Multi-year resistance-training trials in athletes have not shown clinically meaningful renal, hepatic, or hematologic adverse signals. The 2017 ISSN position stand reviewed the full safety literature and concluded creatine is safe in healthy adults at doses up to 30 grams per day for 5 years .

The serum-creatinine rise often noted on labs after starting creatine is not a kidney-injury signal. Creatine itself contributes to serum creatinine measurement; the rise reflects increased pool size, not reduced clearance. Cystatin-C-based eGFR estimates and direct GFR measurements (inulin or iohexol clearance) have not shown declines with supplementation in healthy adults .

Patients with pre-existing chronic kidney disease have not been adequately studied to support a confident recommendation. A clinician conversation is appropriate for anyone with known CKD considering creatine.

The hair-loss concern stems from a single 2009 trial in 20 college rugby players reporting a 56 percent rise in serum DHT after 7-day loading. The trial did not measure hair density and was not designed to evaluate hair loss. No follow-up trial has reproduced the finding. The biological plausibility of a single supplement causing androgenic alopecia is weak; the population-level evidence for the claim is weaker than the public-discourse intensity suggests .

What the evidence does not yet resolve

• Whether higher-than-standard doses (10 grams or higher per day) produce additional benefit for cognition specifically, beyond the muscle-saturation effect.
• Whether non-responders (the roughly 20 to 30 percent of users whose muscle creatine content does not change with supplementation) can be identified ahead of time.
• Whether the cognitive benefit observed in older adults requires concurrent resistance training to manifest, or whether it can stand alone.
• How creatine interacts with GLP-1 induced lean-mass loss. There are no published RCTs of creatine plus GLP-1 specifically.
• Whether the small acute hydration effect (intracellular water increase) translates into any meaningful athletic-performance change in heat or endurance contexts.

Editorial summary

Creatine is the supplement with the strongest evidence base in the entire performance-nutrition literature. The strength and lean-mass case is settled; the cognitive case is real but smaller and most consistent under sleep deprivation and in older adults. Safety in healthy adults is well-characterized. The remaining gaps are about responders, cognitive-dose-response, and interactions with newer pharmacologic weight loss, not whether the core effect is real.