Creatine is an endogenous amino acid which is synthesized from simpler amino acids, namely glycine, arginine and the sulfur-containing amino acid methionine. Approximately 95 percent of creatine in the body is stored in skeletal muscle.
Creatine is produced in the body from foods such as meat or fish, but also from various supplements. It is formed in the kidneys, liver and pancreas, and then secreted into the bloodstream, entering the cells via a transporter protein CRT. This helps creatine cross the blood-brain barrier as well.
Creatine supplement - Image Credit: Casimiro PT / Shutterstock
What Does Creatine Do?
Creatine is best known for its role in energy metabolism, being responsible for the production of adequate amounts of adenosine triphosphate (ATP) in skeletal muscle through the process of oxidative phosphorylation inside the mitochondria.
Muscle contraction is highly energy-intensive, exhausting available muscle stores of ATP within a few seconds. The adenosine diphosphate (ADP) thus formed is regenerated in a cycle which involves the enzyme creatine kinase and phosphocreatine. Creatine is also important in mitochondrial regulation and antioxidant mechanisms in the body.
For all these reasons, creatine supplementation is useful to increase creatine phosphate stores. Phosphocreatine shifts the equilibrium towards ADP phosphorylation to form ATP, so that rapid muscle movement is maintained by keeping energy stores constant, especially under anaerobic conditions. It also improves protein synthesis and helps the body to retain fluids.
Creatine is, therefore, very much in the limelight as a dietary supplement with various uses. The most common use is to improve athletic performance by increasing the lean mass, as well as muscle power. It is also taken by older adults to improve muscle strength.
Young athletic people have been found to increase their muscular mass with the use of creatine during high-intensity sports such as sprinting or resistance exercises. Creatine is found in most sports nutrition supplements in the US, and thus accounts for a sizable share of the $2.7 billion annual sports nutrition supplement market.
However, creatine is also important for its potential role in preventing or slowing the onset and progress of neurodegenerative conditions that occur in association with aging, such as Alzheimer’s disease, Parkinson’s disease, as well as for helping to maintain muscle mass in old age. Muscular weakness is a major reason for elderly people to seek assisted living, because by the time an individual is 80 years old, muscle mass has reduced by about a third. This can lead to (or worsen) the impact of conditions such as congestive cardiac failure, gyrate atrophy in the eye, insulin insensitivity syndromes and malignancies, all of which are far more frequent with aging.
Effects on the Brain
In relation to the brain, creatine may have neuroprotective effects due to its antioxidant actions, by reducing the damaging impact of many neuronal toxins. It may thus protect against many ‘inevitable’ effects of aging-related metabolite buildup. It is thought to improve many psychological conditions such as bipolar disorder and depression.
Other possible creatine deficiency syndromes include chronic obstructive pulmonary disease (COPD), inflammatory myopathies, multiple sclerosis, Rett syndrome, muscle cramps, sleep apnea in infants, schizophrenia, and post-surgical recovery periods. It may also slow down skin aging. Nevertheless, additional research is needed to confirm its use in these areas.