So what Is Creatine?
Creatine is a compound that's naturally made in our bodies to supply energy to our muscles. Chemically, it is called "methylguanido-acetic acid." Creatine is formed from the amino acids arginine, methionine, and glycine through a chemical process which is not worth explaining.
Creatine is manufactured in the liver and may also be produced in the pancreas and kidneys. It is transported in the blood and taken up by muscle cells, where it is converted to creatine phosphate (CP), also called "phosphocreatine." This reaction involves the enzyme creatine kinase which helps bond creatine to a high-energy phosphate group.
Typically, the average person metabolizes about two grams of creatine per day, and that same amount is normally synthesized by the body; thus, you generally maintain a creatine balance. Once creatine is bound to a phosphate group, it is permanently stored in a cell as phosphocreatine until it is used to produce chemical energy called adenosine triphosphate (ATP). When this takes place, creatine can be released to spontaneously form creatinine, which is then removed from the body via the kidneys and excreated in the urine. Creatinine is routinely checked in blood tests, serving as a crude, suggestive marker of how the kidneys are filtering the blood. Although creatine supplementation can raise blood creatinine, it has never been shown to be toxic or harmful to the kidneys.
The richest source of creatine in food is in animal muscle, such as meats and fish. But, to increase athletic performance and boost lean muscle mass, creatine must be taken in concentrations which are not reasonably obtained from a whole-food diet. For example, you would have to consume ten pounds of raw steak a day for five days to load your body with creatine. (Vegetarians usually have a very low intake of creatine, by the way.)
