Creatine is a compound naturally produced by the body and commonly used as a dietary supplement to enhance athletic performance. Dr. Mehdi Boroujerdi reviewed creatine in the Handbook of Creatine and Creatinine In Vivo Kinetics, providing insights into its mechanisms and potential applications.
Mechanisms
Creatine is synthesized in the liver, kidneys, and pancreas from amino acids glycine, arginine, and methionine. It is transported to tissues, primarily skeletal muscle (about 95% of body stores), where it is converted to phosphocreatine. Phosphocreatine helps regenerate adenosine triphosphate (ATP), the main energy currency of cells, supporting high-energy-demand tissues during intense activity.
Supplementation and Performance
Creatine monohydrate, the most studied form, increases muscle creatine and phosphocreatine levels, enhancing ATP regeneration during short, high-intensity activities. This may improve power output, sprint performance, and training capacity. Some studies suggest potential cognitive benefits for memory, mood, and processing speed, particularly in older adults or those with lower baseline creatine levels. Research is exploring roles in conditions like Parkinson's disease, depression, and menopause-related muscle loss, but more trials are needed.
Dosing and Factors
A common protocol involves a loading phase of 20 g/day (split into four doses) for 5–7 days, followed by 3–5 g/day maintenance. Lower daily doses (3–5 g) achieve similar saturation over about 28 days. Absorption can be enhanced by co-ingestion with carbohydrates. Responses vary by sex, age, and diet; women, older adults, and vegetarians/vegans may experience greater relative effects.
Safety
Creatine is generally considered safe for healthy individuals. Concerns about kidney damage have not been substantiated in healthy people, but those with pre-existing kidney conditions should consult a healthcare provider. Creatine does not directly build muscle; its effects depend on baseline levels, dosage, and individual biology. Excess creatine is excreted as creatinine.
Expert Statement: According to Dr. Boroujerdi, "Creatine's role in muscle development is solely to provide energy for contraction and respiration; it is certainly not a substitute for steroids." He added that with appropriate dosing, creatine may eventually be recognized as an over-the-counter therapeutic agent.
Limitations
Creatine is not a panacea; it does not replace training or nutrition. Larger doses do not yield greater benefits due to saturation limits. Effects are not uniform across individuals.