Creatine is a compound the body assembles from three amino acids and stores mostly in skeletal muscle. The National Institutes of Health Office of Dietary Supplements places its benefit in short, intense, repeated efforts — sprints, lifts, repeated maximal contractions — and describes it as of little value for endurance sports such as distance running or swimming.
That is a narrower claim than the shelf marketing around creatine suggests, and it is also one of the better-evidenced claims in sports nutrition. What follows sets out what named institutions and published reviews say creatine does, what they say it does not do, and where the evidence thins out. It is information, not medical advice; decisions about whether to use any supplement belong with a qualified clinician.
What is creatine, and where does it come from?
Creatine is both made inside the body and eaten in food. The NIH Office of Dietary Supplements, in its fact sheet on supplements for exercise and athletic performance, states that the liver and kidneys synthesize about 1 g per day of creatine from the amino acids glycine, arginine and methionine.
Food supplies the rest. The same fact sheet gives beef at about 2 g per pound, pork at about 2.3 g per pound and salmon at about 2 g per pound.
Mayo Clinic's reference material describes creatine in the same plain terms: a compound built from three amino acids, held mostly in muscle with smaller amounts in the brain, and produced by the liver, kidneys and pancreas. Nothing about it is exotic. What a supplement changes is the size of an existing store, not the presence of a new substance.
How does creatine work in muscle?
The proposed mechanism is a battery, not a stimulant. Muscle contraction runs on ATP — adenosine triphosphate, the molecule cells spend for energy. A muscle holds only a few seconds of ATP at a time, and phosphocreatine is the reserve it uses to rebuild that ATP immediately.
The NIH fact sheet lists the routes by which creatine is thought to act: increasing stores of phosphocreatine used to generate ATP at the beginning of intense exercise, accelerating the resynthesis of phosphocreatine after exercise, slowing the breakdown of adenine nucleotides and the accumulation of lactate, and possibly improving glycogen storage in skeletal muscle.
Two consequences follow from that description. First, the effect should show up in efforts lasting seconds and repeated with short rests, which is what the performance evidence reports. Second, it should do comparatively little in efforts limited by oxygen delivery over many minutes, which is also what the evidence reports.
What does the evidence show for strength and power?
This is where creatine's case is strongest. The International Society of Sports Nutrition, in its 2017 position stand led by Richard Kreider and colleagues in the Journal of the International Society of Sports Nutrition, calls creatine monohydrate the most effective ergogenic nutritional supplement currently available to athletes for increasing high-intensity exercise capacity and lean body mass during training.
The same document reports that once muscle stores are loaded, performance of high-intensity or repetitive exercise is generally increased by 10 to 20 percent, depending on how much muscle phosphocreatine rises. That range is wide because the response is not uniform: people who start with low stores have more room to gain than people who start near saturation.
A position stand is a professional society's consensus reading of a literature, not a single controlled trial, and the society in question is a sports-nutrition body. It carries the weight of a considered summary rather than of a definitive experiment. The NIH fact sheet, written by a government office with no stake in the category, reaches a compatible conclusion: creatine often significantly increases strength, such as in bench presses, and power, such as in cycling, in work involving multiple sets of maximal-effort contractions, with reported improvements in sprinting, weight lifting and soccer performance.
Both sources agree on the boundary as well. The NIH fact sheet calls creatine of little value for endurance sports, because the ATP-creatine system is not the limiting one there. Mayo Clinic frames the muscle-size and strength finding as applying when creatine is combined with resistance training, not on its own.
Does creatine do anything for the brain?
The cognitive evidence is much weaker than the muscle evidence, and it is mixed. A 2024 systematic review and meta-analysis in Frontiers in Nutrition by Chen Xu and colleagues pooled 16 randomized controlled trials with 492 participants aged roughly 21 to 76, including both healthy adults and people with diagnosed conditions.
Memory was the one outcome with a clear pooled signal: a standardized mean difference of 0.31, with a 95 percent confidence interval of 0.18 to 0.44. In plain terms that is a small effect that the pooled data separate from zero. Attention time and processing-speed time also reached statistical significance, at standardized mean differences of −0.31 and −0.51 respectively.
The null results matter as much. The same analysis found no significant effect on overall cognitive function or on executive function. Its authors describe heterogeneity in trial design, sample size and testing methods, note that small samples limited statistical power, and rate the certainty of the evidence for processing speed, overall cognitive function, executive function and attention as low.
The subgroup patterns are interesting and unconfirmed. The review reports that participants with diseases benefited more than healthy participants, that adults aged 18 to 60 showed attention benefits where those over 60 did not, and that longer interventions did not outperform shorter ones. Subgroup findings inside a 492-person pooled analysis are hypotheses for future trials, not conclusions. Mayo Clinic likewise lists cognition among possible rather than established benefits.
Is creatine safe, and what about the kidneys?
The published safety record in healthy adults is reassuring, and the kidney worry is the most persistent claim that the evidence does not support. The ISSN position stand states that short- and long-term supplementation, at up to 30 g per day for five years, is safe and well tolerated in healthy individuals, and reports no clinically significant differences between creatine users and controls in markers of renal function.
The Mayo Clinic entry on creatine puts it in similar terms: taken by mouth at recommended doses, creatine is likely safe for many people for up to five years. It acknowledges that some older reports suggested creatine might worsen kidney function, but says studies in healthy people show no harm at recommended doses. It adds that people with kidney disease may want to talk with their healthcare teams before using it.
Reported side effects are modest and mostly mechanical. The NIH fact sheet lists weight gain from water retention, along with anecdotal reports of nausea, diarrhea, muscle cramps, muscle stiffness and heat intolerance — anecdotal being the operative word, since the ISSN position stand states there is no evidence that creatine increases the anecdotally reported incidence of musculoskeletal injuries, dehydration, cramping, gastrointestinal upset or renal dysfunction. Mayo Clinic also notes that caffeine taken alongside creatine may reduce its effectiveness. None of this replaces a clinician's assessment of an individual's medications and medical history.
What doses have the studies used?
The figures below describe what published protocols used. They are attributed facts about research, not recommendations, and nothing here is a protocol to follow; dosing decisions belong with a qualified clinician.
| Approach | What the cited sources describe | Source |
|---|---|---|
| Loading then maintenance | 20 g per day of creatine monohydrate in four 5 g portions for 5 to 7 days, followed by a maintenance phase of 3 to 5 g per day | NIH Office of Dietary Supplements |
| Loading then maintenance (society reading) | 5 g, or about 0.3 g per kilogram of body weight, four times daily for 5 to 7 days, then 3 to 5 g per day, with larger athletes described as needing 5 to 10 g per day | ISSN position stand, 2017 |
| No loading phase | Single doses of about 3 to 6 g per day for 3 to 4 weeks | NIH Office of Dietary Supplements |
The two loading descriptions differ slightly in how they express the same idea, and the no-loading route is presented as reaching a similar endpoint more slowly. Neither source presents one as superior for an individual reader.
Which form of creatine has actually been studied?
Creatine monohydrate is the form the research rests on. The NIH fact sheet describes it as the most widely used and studied form among the various creatine formulations sold. The ISSN position stand's efficacy and safety statements are likewise written about monohydrate.
Products sold as buffered, liquid, hydrochloride or micronized creatine make their own comparative claims about absorption, tolerance or potency. Those are the manufacturers' claims, presented here as such and not verified by this publication. Where a form has not been studied in published trials, the evidence base for monohydrate does not automatically transfer to it.
How are creatine supplements regulated?
Differently from drugs. The US Food and Drug Administration states in its dietary supplements overview that it regulates dietary supplements under a different set of regulations than those covering conventional foods and drug products.
Under the Dietary Supplement Health and Education Act, the FDA says, manufacturers and distributors are prohibited from marketing products that are adulterated or misbranded, and those firms are responsible for evaluating the safety and labeling of their products before marketing. The agency describes its own authority as the power to act against an adulterated or misbranded dietary supplement after it reaches the market.
In practice that means no premarket approval of the kind drugs receive, no government verification that a tub contains what the panel says, and no approval to treat, cure or prevent any disease. A creatine product's identity and purity are the maker's responsibility, and third-party testing programs are commercial services, not regulatory ones.
What the evidence supports, in one place
Creatine has a plausible, well-described mechanism and consistent evidence for one narrow job: short, hard, repeated efforts, and lean mass gained alongside resistance training. Its safety record in healthy adults is among the better-documented in the category, and the kidney claim is not supported by the cited sources. Its cognitive case rests on one small pooled analysis with a single clear outcome and several null ones, rated low certainty by its own authors. Everything else on a creatine label is a manufacturer's claim.
This article is information, not medical advice. Anyone weighing a supplement against their own medications, kidney function or training goals should raise it with a qualified clinician. The evidence summarized here was reviewed as of August 20, 2026.
For a related nutrition perspective, read How Creatine Monohydrate Actually Works in Muscle: The Evidence.