HMB is an amino acid, but derives from the breakdown of Leucine, a part of normal dietary protein. HMB can be also found in certain foods like catfish, alfalfa & it is also a natural component of mother's milk, but is scarcely found in a normal diet. HMB was discovered in the 1950's & has been studied for several decades, but has only really become popular as a sports supplement around 1995. HMB has been proven to slow down the breakdown of muscle protein as well as promote lean gains, which means that it has both tissue sparing & tissue building qualities. Early studies have shown that HMB supplementation also lowers cholesterol & helps strengthen the immune system.