Creatine: what it is, how the body uses it, and how to get enough

Creatine is a naturally occurring compound the body makes from the amino acids glycine, arginine, and methionine. It is stored mostly in skeletal muscle, with smaller amounts in the brain, kidneys, and liver. In the body, creatine helps recycle energy rapidly through the phosphocreatine system, which matters most when tissues need quick bursts of fuel.¹²

Creatine matters because it sits at the intersection of basic energy metabolism and practical performance. The most consistent use case is supporting resistance training, where creatine may help people train a little harder and gain more strength. Interest has also grown around healthy aging and cognition, but those areas are less settled than the exercise literature.⁶⁹¹¹

The best-supported benefit is improved strength and power when creatine is taken alongside resistance training. Recent meta-analyses report greater upper- and lower-body strength gains with creatine plus training than with training alone. That is the clearest place where the evidence is strongest and most consistent.⁶⁷¹

Creatine has also been studied for recovery after exercise-induced muscle damage, cognition, and glucose handling. Recovery and soreness results are promising but narrower than the strength literature. Cognition findings are mixed: some reviews suggest possible memory benefits in healthy people, especially older adults, while other reviews find heterogeneous or contradictory results. Evidence for glycemic control or insulin resistance remains mixed and should be treated as emerging rather than established.^8179101112

Dietary creatine comes mainly from animal foods, especially red meat and fish, while dairy contains very little. For supplementation, creatine monohydrate is the standard form because it is the most studied and has the best evidence for efficacy and safety. A common study-backed pattern is a loading phase of about 0.3 g/kg/day for 5 to 7 days, followed by 3 to 5 g/day for maintenance. A maintenance-only approach is also reasonable, but it usually takes longer to saturate stores. Third-party testing can be useful when supplement quality matters.^4523320119

Creatine is generally well tolerated in healthy people when used appropriately, but there are some important cautions. People with pre-existing kidney disease, very low GFR, or unexplained kidney abnormalities should be cautious, and creatinine-based lab results can be harder to interpret in creatine users. Pregnant or breastfeeding people should be conservative and discuss supplement use with a clinician because lactation data are limited. Loading doses can also be harder on people with gastrointestinal sensitivity, and early weight gain from water retention may matter for people concerned about fluid shifts or body mass.^{1314115171816}

Creatine can reasonably be described as a useful supplement for performance support, especially strength and power, and it may have some secondary benefits in selected settings. It should not be presented as a cure-all for longevity, metabolism, cognition, or disease prevention. Benefits depend on the person, the training program, the dose, and the baseline diet; people who eat little animal food may notice a different starting point than people who already get more from diet.^69121114