Creatine ethyl esters (CEE) are a popular form of creatine marketed to have several advantages over creatine monohydrate and other forms of creatine. Esters are compounds made from the combination of an alcohol and a carboxylic acid. The idea behind "esterifying" creatine is that it will change the physical properties of the compound making it more stable and bioavailable at the target tissue. The hope is that an ester bond may protect the compound from being digested in the gastrointestinal tract by typical enzymes or it may increase its solubility so that it is taken up by tissues. Despite heavy marketing, no studies have evaluated CEE compared to creatine monohydrate - until now. Researchers from the United Kingdom tested the stability of two commercially available CEE products compared to creatine monohydrate. Each creatine product was exposed to acidic conditions designed to simulate conditions in the stomach. Serial measurements were then made for creatine and the breakdown product creatinine. A significant portion of the creatine was converted to creatinine for both CEE products, whereas more than 99% of the creatine remained available from the creatine monohydrate product. The findings do not confirm the greater stability of CEE in the gastrointestinal tract, in fact these result indicate that CEE more readily converts to its breakdown product creatinine in acidic environments. The bottom line is that most ester supplements are largely unproven, and unless you see documented clinical data, are probably not worth the additional cost.

Child R, Tallon MJ. Creatine ethyl ester rapidly degrades to creatinine in stomach acid. International Society of Sports Nutrition. Las Vegas, NV, June, 2007.