Background: Creatine is an amino acid made in the liver and stored in muscles. It is a readily available source of energy in the body. In the diet, creatine is found in milk, red meat, and some fish.

Medicinal Claims: Creatine is used to improve physical or athletic performance and to decrease fatigue. A few studies indicate that creatine can increase the amount of work performed with a short maximal effort (for example, in sprinting). However, a few others indicate no improvement in this type of activity.

Possible Side Effects: Creatine can cause dehydration and may cause kidney dysfunction.

Last full review/revision February 2003