Abstract
Human milk has many unique properties that benefit the breast-fed infant. Several of these properties reside in the protein fraction of human milk; eg, host defense factors (such as immunoglobulins, lysozyme, and lactoferrin), digestive enzymes (lipases, proteases, amylase), specific binding proteins, and growth factors. Increased knowledge of human milk proteins and their biochemistry will aid our understanding of their physiological significance in the infant.