WHAT IS ARGININE ETHYL ESTER? Arginine Ethyl Ester, often referred to as AEE, is formed when Arginine is esterified. Specifically, BULK POWDERS™ Arginine Ethyl Ester offers superior absorption over regular Arginine as a result of the Ester attached to the Arginine. Arginine is a pre-cursor to Nitric Oxide production, which makes it a popular component of many pre-workout formulas. Arginine is naturally occurring in the diet, & can be found in dairy products, chicken & fish.