Creatine (Cr)

Creatine is a nitrogenous organic acid that occurs naturally in vertebrates and helps to supply energy to all cells in the body, primarily muscle. This is achieved by increasing the formation of adenosine triphosphate (ATP). Creatine is naturally produced in the human body from amino acids primarily in the kidney and liver. It is transported in the blood for use by muscles. Creatine is not an essential nutrient, as it is manufactured in the human body from L-arginine, glycine, and L-methionine. Creatine, synthesized in the liver and kidney, is transported through the blood and taken up by tissues with high energy demands, such as the brain and skeletal muscle, through an active transport system. The concentration of ATP in skeletal muscle is usually 2-5 mM, which would result in a muscle contraction of only a few seconds. Creatine has been demonstrated to cause modest increases in strength in people with a variety of neuromuscular disorders.