D-Aspartic Acid (DAA) is a non-essential amino acid (made naturally in the body) that is produced in the testes and glands. One recent study shows that supplementing with DAA can increase testosterone levels in as short as 12 days. Increasing testosterone levels is especially important for men over 30 who may be seeing a drop in their test levels. Increased testosterone levels can lead to muscle gain, fat loss, increased sex drive and higher energy levels. The recommended dosage of DAA is 3 grams per day.