Creatine monohydrate, an evidence snapshot covering strength, lean mass, hydration, and cognition

Key takeaways

• Creatine monohydrate at 3 to 5 g per day produces small but consistent improvements in strength and lean mass when paired with resistance training; meta-analyses report effect sizes around 8 percent strength gain over placebo.
• The loading phase (20 g per day for 5 to 7 days, then 3 to 5 g per day) saturates muscle creatine faster but is not required; 3 to 5 g per day reaches the same saturation in roughly 3 to 4 weeks.
• Creatine monohydrate is the most studied form. The literature does not support that other forms (HCl, ethyl ester, buffered) outperform monohydrate.
• The kidney-damage concern is not supported by the published clinical evidence; trials and reviews in healthy adults consistently show no adverse effect on renal function at standard doses.
• Emerging evidence supports modest cognitive effects under sleep restriction and possibly in vegetarians, and a benefit in older adults when paired with resistance training. The clinical evidence in conditions like depression and TBI is preliminary.

What creatine does, mechanistically

Creatine is a non-essential amino acid derivative synthesized in the liver and kidneys, and obtained from meat and fish. In skeletal muscle, creatine is phosphorylated to phosphocreatine, which donates a phosphate to ADP to regenerate ATP during high-intensity work. Higher intramuscular creatine raises the rate at which ATP can be regenerated during the first 10 to 30 seconds of intense effort, which is the practical basis for performance benefits in resistance training, sprints, and repeated short-burst activity. The biology is reviewed in the ISSN position stand on creatine .

Tissue creatine in the brain is roughly 70 to 80 percent of muscle saturation in habitual omnivores; the brain phosphocreatine pool is smaller and slower to turn over. This is part of why creatine effects on cognition emerge most clearly under metabolic stress (sleep restriction, hypoxia) rather than at baseline.

Strength and hypertrophy

The Branch 2003 meta-analysis of 100 studies reported a small but consistent benefit of creatine over placebo on muscle performance, particularly in shorter-duration high-intensity work. More recent meta-analyses by Lanhers et al. and Chilibeck et al. have reproduced the effect in resistance-trained adults, with summary effect sizes corresponding to roughly 8 percent strength improvement and 1 to 2 kg of additional lean mass over weeks of resistance training .

The lean-mass effect is partly water (intracellular hydration rises with creatine loading), and partly true muscle protein accretion when paired with resistance training. The ISSN position stand reviews both contributions .

Loading vs. maintenance dosing

• Loading: 20 g per day (4 doses of 5 g) for 5 to 7 days, then 3 to 5 g per day. Saturates muscle creatine in about a week.
• No loading: 3 to 5 g per day reaches the same saturation in 3 to 4 weeks.
• Maintenance: 3 to 5 g per day indefinitely. Larger or heavier individuals may benefit from the upper end of the range.
• Timing: post-workout co-ingested with carbohydrate or protein modestly improves uptake in some studies, but absolute differences are small. Total daily dose matters more than timing.

GI tolerance is the most common reason loading fails. Splitting the loading dose into 4 to 5 servings per day with food usually addresses it. Creatine HCl and other alternative forms cite better solubility, but no published trial has shown superior performance outcomes vs. monohydrate.

Safety and the kidney-function question

Creatine raises serum creatinine because creatinine is creatine's metabolic breakdown product. The rise can falsely flag a kidney-injury reading if the supplementation context is not known. The actual published evidence in healthy adults consistently shows no adverse effect on glomerular filtration rate, kidney structure, or kidney biomarkers like cystatin C at supplementation doses for periods up to several years . The ISSN position stand and follow-up reviews both summarize the kidney-safety literature .

Adults with pre-existing chronic kidney disease should discuss creatine with a clinician because the population is underrepresented in the supplementation trials, but the evidence base in healthy adults is robust. The ODS NIH dietary supplement fact sheet covers the regulatory and safety framing in plain language .

Cognition, mood, and older adults

Creatine effects on cognition emerge most clearly under metabolic stress. Trials in sleep-deprived adults and vegetarians (whose dietary creatine intake is low) report measurable cognitive benefits with supplementation. Effects in well-rested omnivores at baseline are smaller and less consistent. The Avgerinos et al. 2018 meta-analysis summarizes the cognitive literature .

In older adults, resistance training with creatine supplementation produces larger gains in lean mass and strength than resistance training alone in several trials. The Chilibeck et al. 2017 meta-analysis specifically of older adults reported improvements in chest-press strength and lean mass over training-only controls .

What the evidence does not show

• Creatine does not meaningfully improve endurance performance in long-duration aerobic events.
• Alternative forms (HCl, ethyl ester, magnesium chelate, buffered) have not outperformed monohydrate in head-to-head trials despite higher prices.
• Creatine has not been demonstrated to treat or prevent any disease. The ODS NIH fact sheet documents the dietary-supplement posture .
• Hair loss claims trace primarily to one 2009 study reporting an increase in dihydrotestosterone with creatine in rugby players; the finding has not been replicated, and a clinical hair-loss outcome has not been demonstrated.