Creatine ethyl ester, also known as creatine ester, cre-ester an CEE, is a substance sold as an aid for athletic performance and for muscle development in bodybuilding. It is an ethyl ester derivative of creatine, from which it is made. In the body, CEE is converted back into creatine. The ethyl ester is said to have a much better absorption rate and a longer half-life in the body than regular creatine monohydrate, because it is slightly more lipophilic. However, these claims have not yet been conclusively proven by independent research, and in fact a study presented at the 4th International Society of Sports Nutrition (ISSN) annual meeting demonstrated that that the addition of the ethyl group to creatine actually reduces acid stability and accelerates its breakdown to creatinine. The researchers concluded that creatine ethyl-ester is inferior to creatine monohydrate as a source of creatine.