Creatine: The Most Researched Supplement for Performance, Cognition & Longevity

What creatine is and how it works

Creatine is not exotic. It is a compound your body makes from three amino acids — arginine, glycine, and methionine — and obtains through food, primarily meat and fish. Around 95% of the body's creatine is stored in skeletal muscle, with the rest distributed in the brain, heart, and other tissues.

The mechanism is well understood. During short, intense efforts — a sprint, a heavy lift, a repeated jump — muscles burn ATP (adenosine triphosphate) faster than aerobic metabolism can regenerate it. Phosphocreatine stored in the muscle acts as an immediate buffer: it donates a phosphate group to ADP to rapidly regenerate ATP, extending the period during which muscles can produce maximal force before fatigue sets in.

Supplemental creatine monohydrate raises the total creatine and phosphocreatine content of muscle above what diet and endogenous synthesis alone can achieve. The practical effect is a larger phosphocreatine reservoir — more fuel available for repeated high-intensity efforts before output falls off.

This is why creatine's benefits cluster around high-intensity, short-duration work. It does not meaningfully improve steady-state aerobic performance lasting more than a few minutes, where the aerobic system has time to regenerate ATP at the required rate.

Physical performance: what the research has measured

Creatine monohydrate has been studied in controlled trials for over thirty years. The evidence base is unusually large and unusually consistent by supplement standards.

Strength

A meta-analysis by Rawson and Volek (2003) pooled 22 randomised trials and found creatine supplementation increased maximum strength — measured by one-rep max on compound lifts — by approximately 8% compared to 4% for placebo. That 4-percentage-point difference represents a genuine additive effect on top of training alone [1].

More recent systematic reviews confirm the effect across populations: trained athletes, untrained beginners, older adults, and women. The magnitude is consistent: somewhere between 5–15% improvement in strength outcomes across studies, with the largest effects in protocols that include progressive resistance training alongside supplementation [2].

Power output and high-intensity work

Branch's 2003 meta-analysis found a mean improvement of approximately 7.5% in total work performed during high-intensity intermittent exercise tasks [3]. Sprint performance, peak cycling power, and repeated jump height are consistently improved in controlled trials. The effect is most pronounced in protocols requiring multiple bouts — where phosphocreatine depletion and resynthesis rate between efforts is the limiting factor.

Lean mass

Creatine supplementation increases body mass by 1–2 kg in the first 1–2 weeks. This is largely water drawn into muscle cells alongside creatine — an intramuscular change, not subcutaneous bloating. Longer-term gains of 1–2 kg of actual lean mass above training-only controls have been measured over 4–12 week trials, contingent on concurrent resistance training [2].

Creatine monohydrate as the gold-standard form

The supplement industry offers creatine in multiple forms: ethyl ester, buffered creatine (Kre-Alkalyn), creatine HCl, creatine nitrate. A 2011 review by Jäger and colleagues examined the evidence base for each alternative form and found no well-controlled trial demonstrating superiority over monohydrate for any outcome [4]. Monohydrate is the form with decades of evidence. The alternatives have marketing but not the trials.

Cognition and the brain: emerging evidence

The brain uses substantial quantities of creatine. Neural tissue has its own creatine kinase system and depends on phosphocreatine buffering during periods of high cognitive demand. This is the rationale for studying creatine's cognitive effects.

The evidence here is promising but less settled than the muscle performance literature. A 2022 systematic review by Forbes and colleagues analysed six randomised controlled trials and found that creatine supplementation improved short-term memory and performance on intelligence and reasoning tasks in healthy adults [5]. The effect sizes were modest but consistent across studies.

The contexts where cognitive benefits are most robust:

• Sleep deprivation. A 2006 study by McMorris and colleagues found creatine supplementation significantly attenuated the cognitive decline caused by 24 hours of sleep deprivation [6]. This fits the mechanistic picture: sleep deprivation reduces brain creatine and phosphocreatine; supplementation partially restores the buffer.
• Lower dietary creatine intake. Vegetarians and vegans have lower baseline muscle and brain creatine than omnivores. Studies in these populations tend to show larger cognitive benefits from supplementation [5].
• Ageing. Brain creatine content and creatine kinase activity decline with age, providing a plausible mechanism for age-related cognitive benefits from supplementation.

Longevity and ageing: muscle preservation and beyond

The relevance of creatine extends beyond athletic performance. Sarcopenia — the progressive loss of muscle mass and function with age — is one of the most significant drivers of disability and loss of independence in older adults. Creatine supplementation, combined with resistance training, has been studied as an intervention to slow this process.

A 2017 systematic review and meta-analysis by Lanhers and colleagues found that creatine supplementation combined with resistance training produced significantly greater gains in lower-limb strength in older adults compared to resistance training alone [7]. A broader review of the ageing literature by Candow and colleagues concluded that creatine supplementation enhances lean mass and functional performance in older adults above training-only controls [8].

The mechanism is the same as in younger populations — greater phosphocreatine availability supports higher training intensity and volume — compounded by evidence that creatine may have direct effects on muscle protein synthesis signalling pathways, though this area is less conclusive than the training-augmentation effect.

Bone

Some evidence suggests creatine may support bone mineral density. A 2014 randomised trial by Chilibeck and colleagues found that creatine combined with resistance training produced greater gains in femoral neck bone mineral content in older men compared to training alone [9]. This finding remains preliminary — it is not replicated across multiple large trials — but the direction of effect is consistent with the muscle preservation evidence and the plausible mechanism of higher mechanical loading from greater strength.

Realistic framing for longevity use

Creatine is not a longevity intervention in isolation. Its value in the context of ageing is as an augment to resistance training — it makes training more effective, and resistance training has one of the strongest evidence bases for functional healthspan preservation available. The combination of consistent resistance training and adequate creatine intake is better supported by the evidence than either alone.

How to take it

The most important finding from thirty years of dosing research is that simple daily maintenance outperforms complicated protocols.

The early-week water retention — typically 1–2 kg — reflects creatine drawing water into muscle cells alongside it. This is intramuscular, not subcutaneous. It is not the same as the puffiness associated with high sodium intake or poor sleep. Most people do not notice it subjectively.

Safety

Creatine monohydrate has one of the strongest safety records of any widely-used supplement. The International Society of Sports Nutrition's 2017 position stand — a systematic review of the available evidence — concluded that creatine monohydrate is safe for healthy individuals at recommended doses across short and long-term use [12].

Kidney function and the creatinine artefact

This is the most common source of confusion around creatine safety. Creatine metabolism produces creatinine, a waste product filtered by the kidneys and measured in routine blood panels as a marker of kidney function. Creatine supplementation raises serum creatinine — not because it is damaging the kidneys, but because there is simply more creatine being metabolised.

Multiple trials with direct measures of kidney filtration (glomerular filtration rate, creatinine clearance) in creatine-supplementing individuals have found no adverse effect [12]. The elevated creatinine on a blood panel is a measurement artefact, not evidence of impairment. Clinicians who see elevated creatinine in a patient taking creatine should note the supplementation before interpreting the value.

The appropriate caveat: individuals with pre-existing kidney disease have not been studied extensively in controlled trials and should consult a clinician before supplementing.

Hair and DHT

A 2009 study in South African rugby players reported elevated dihydrotestosterone (DHT) — a hormone associated with male-pattern hair loss — following a creatine loading protocol [13]. This finding has not been replicated in subsequent controlled trials. No study has directly demonstrated creatine-induced hair loss. The DHT finding remains a single unreplicated result; it cannot be dismissed entirely, but it should not be treated as established.

GI tolerance

Loading protocols (20 g/day split across doses) can cause transient nausea or diarrhoea in some individuals. Gradual dosing at 3–5 g/day avoids this in the large majority of people.

Bottom line: who benefits and what to expect

Creatine monohydrate is worth considering for anyone who:

• Performs resistance training and wants to maximise strength and lean mass gains
• Does any sport involving repeated high-intensity efforts — sprinting, team sports, combat sports, CrossFit
• Is over 50 and doing resistance training for health and function
• Eats little or no meat and wants to maintain baseline muscle and brain creatine stores
• Regularly operates under sleep deprivation and wants to partially mitigate cognitive impact

Realistic expectations from consistent 3–5 g/day supplementation combined with resistance training: modest but real improvements in strength and power output (5–15% above training alone in the literature); 1–2 kg additional lean mass over a 4–12 week programme; support for muscle preservation and functional capacity with age. The cognitive benefits are real but smaller, most pronounced under conditions of metabolic stress.

What creatine does not do: replace training, improve endurance performance lasting more than a few minutes, or produce dramatic body composition changes in isolation. The supplement augments training — it does not substitute for it.

The practical check for any creatine-containing product: the dose matters. Products containing less than 3 g of creatine monohydrate per serving — or proprietary blends that obscure the creatine quantity — are likely below the threshold with consistent trial evidence. Monohydrate at 3–5 g/day is the form and dose with the evidence behind it.

Related Proco pages

• What "recovery" means in performance research
• Zone 2 training: what the research has measured
• HRV: what it measures and what affects it
• The hallmarks of aging: what the research describes
• How to read a clinical trial

Sources