Creatine

Creatine monohydrate is among the most extensively studied supplements in sports nutrition, with a body of evidence spanning several decades and hundreds of controlled trials. Its primary mechanism involves increasing intramuscular phosphocreatine stores, which rapidly regenerate ATP during high-intensity, short-duration activity — the energy pathway most relevant to resistance training, sprinting, and explosive sports. The evidence for creatine's effects on muscle strength, power output, and lean mass is exceptionally strong. The International Society of Sports Nutrition (ISSN) position stand (Kreider et al., 2017) — a comprehensive synthesis of the available literature — concludes that creatine monohydrate is "the most effective ergogenic nutritional supplement available to athletes for increasing high-intensity exercise capacity and lean body mass." Meta-analyses corroborate this, showing consistent, statistically significant effects across populations (Branch 2003). The typical protocol involves either a loading phase (20 g/day in divided doses for 5–7 days) followed by maintenance (3–5 g/day), or a simpler daily maintenance approach without loading — both are effective, with the loading phase producing faster saturation. A growing body of evidence suggests creatine may also benefit cognitive function. A well-designed double-blind crossover RCT (Rae et al., 2003, n=45) in vegetarians found that 5 g/day for 6 weeks significantly improved working memory and intelligence test scores, with elevated brain phosphocreatine levels providing a plausible energetic mechanism. Vegetarians typically have lower baseline muscle and brain creatine stores, which may explain the stronger effects observed in this population. Evidence in omnivores is more limited, though mechanistic reasoning supports potential cognitive benefit particularly under conditions of cognitive stress, sleep deprivation, or aging. Emerging research also supports creatine's relevance for aging populations. Sarcopenia — the progressive loss of skeletal muscle with age — is a significant driver of morbidity and loss of independence, and creatine supplementation combined with resistance training shows promise for attenuating this decline. Some early research suggests potential neuroprotective properties relevant to neurological conditions, though this remains an active area of investigation with limited clinical trial evidence. The safety profile of creatine at standard doses (3–5 g/day) is well-established. Despite earlier concerns, there is no credible evidence of kidney harm in healthy individuals at these doses. The main reported side effects are transient weight gain (from increased intramuscular water retention) and mild GI discomfort in some individuals during loading. Creatine monohydrate is the most studied form; other forms (HCl, ethyl ester, buffered) have limited head-to-head evidence and typically cost more without demonstrated superiority.