There are 20 amino acids which are used as building blocks for proteins.  Twelve of the amino acids can be made in the body from other amino acids, carbohydrates and nitrogen.  These are called nonessential amino acids.  The other eight are called essential amino acids, meaning they must be supplied in the diet.  Branch chain amino acids (BCAAs) include three of the essential amino acids:  valine, leucine and isoleucine.

BCAA supplements help prevent the break down of muscle tissue during intense exercise.  They make up one-third of muscle protein and are a vital substrate for two other amino acids, glutamine and alanine which are released in large quanities during intense exercise.  BCAA supplementation before, during and after prolonged exercise can reduce muscle damage by reducing muscle protein breakdown.