Mean (±SEM) plasma phenylalanine (pPHE, panel a), leucine (pLEU, panel b) and essential amino acid (pEAA, panel c) concentrations before and after intake of a hydrolyzed casein (hCAS), hydrolyzed casein with leucine addition (hCAS+LEU), hydrolyzed whey (hWHEY), and hydrolyzed whey with leucine addition (hWHEY+LEU) protein meal. pPHE concentration: time effect, P<0.0001; protein meal effect, P<0.0001; time × protein meal interaction, P=0.0216. pLEU concentration: time effect, P<0.0001; protein meal effect, P<0.0001; time × protein meal interaction, P<0.0001. pEAA concentration: time effect, P<0.0001; protein meal effect, P<0.0001; time × protein meal interaction, P<0.0001.*hCAS significantly different from hWHEY, P<0.05. **hCAS+LEU significantly different from hWHEY+LEU, P<0.05. #hCAS significantly different from hCAS+LEU, P<0.05. $hWHEY significantly different from hWHEY+LEU, P<0.05.