When you consume protein from foods such as meat and fish the protein is not directly absorbed in your body. First the protein must be digested and turned into amino acids. To do this the digestive enzymes in your body cleave the proteins' peptide bonds. The amino acids are then absorbed in your gut. This process generally takes three to four hours.
By contrast amino acids do not need to be further digested and your body can absorb them in about 30 minutes.
Branched-chain amino acids (BCAAs) comprise the three essential amino acids valine, leucine and isoleucine. BCAAs are of particular interest for sports performance