The use of nutritional supplements for sport continues to increase, with athletes and recreationally active trainees increasingly look for methods to improve performance. Many athletes have turned away from drugs like anabolic steroids toward nutritional supplements in the hope of gaining a competitive edge without threatening their health. Sport supplements can be defined as any product taken by the mouth, and that has been proposed to have a performance-enhancing effect. Supplements that are used to enhance athletic performance also called ergogenic aids. The use of supplement by athletes to improve performance is not a new practice. As early as BC 776, the Greek Olympians were reported to use substances such as dried figs, mushrooms, and strychnine to perform better. In recent years an explosion of information concerning sports nutrition has surfaced. In this book, only substances that are not currently banned by the World Anti-Doping Agency will be reviewed.