DAA is a non-essential amino acid, which occurs naturally in the human body. It is associated with having an impact on male fertility and testosterone levels. Testosterone plays an important role in many physiological processes. It is crucial in adolescence, during sexual maturing, as it influences fertility, reproductive functions and the proper functioning of sex organs. It can increase libido and also impacts the size and strength of muscles, as well as the density of bone tissue. DAA itself is often used as a substitute for steroids. It takes its effect in the brain and facilitates the release of luteinizing and growth hormone, which in effect increases muscle growth.