Creatine is an amino acid made in the liver and stored in muscles. When combined with phosphate, it is a readily available source of energy in the body. In the diet, creatine is found in milk, red meat, and some fish.
(See also Overview of Dietary Supplements.)
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health (NIH), National Center for Complementary and Integrative Health: Dietary Supplements Marketed for Weight Loss, Bodybuilding, and Sexual Enhancement: What the Science Says