Amino acids are the building blocks of protein, and OPTIMUM NUTRITION ESSENTIAL AMINO ENERGY (270G) provides a great way to get them into your diet. This product is a complete amino acid supplement that includes all the essential amino acids. It is also a good source of energy, with each serving providing 100 mg of caffeine. This product is perfect for anyone looking for a way to boost their energy levels and get the most out of their workouts. Amino Energy by optimum nutrition is also a great choice for those trying to build muscle mass, as it can help stimulate muscle growth.