Plasma free amino acid levels in human subjects after meals containing lactalbumin, heated lactalbumin, or no protein

Abstract
Plasma free amino acids were measured in six adult human subjects at four consecutive ½ hr intervals following meals containing either 50 g lactalbumin, 50 g heated lactalbumin, or no protein. After the lactalbumin meal, all essential and several nonessential amino acids increased in the plasma. After the heated lactalbumin meal, these increases were either much less or did not appear. Following the no protein meal all measured plasma amino acids fell. The absence of a response to the heated lactalbumin meal was considered to be related to a drop in digestibility of heated lactalbumin as measured in rats.