Hormones and growth factors in milk.

Research dealing with hormones/growth factors in milk has progressed rapidly during the last 10 yr from their identification in milk to their regulation of various functions in the maternal organism and in the neonate. Many hormones, growth factors, and bioactive substances present in the maternal organism are present in colostrum and milk, often exceeding concentrations that occur in maternal plasma. Some appear in milk in different, sometimes multiple, forms from that found in maternal serum, reflecting to some extent synthesis and posttranslational processing by mammary tissue. Recent research has indicated that many milk hormones/growth factors survive the environment of the gut of the neonate, become absorbed into the neonatal circulation, and exert important functions in the neonate.