The concentration of epidermal growth factor in Japanese mother's milk

The concentration of epidermal growth factor (EGF) in human milk was measured by radioreceptor assay (RRA). Human milk samples collected from healthy Japanese mothers who delivered at full term were divided into 30 groups according to differences in the duration of lactation, seasons of the year and place of residence. Human milk collected from 3 to 5 days after delivery in winter and summer contained 15.03 micrograms/100 ml and 15.46 micrograms/100 ml of EGF, respectively. The concentrations decreased rapidly to 8.04 micrograms/100 ml and 8.12 micrograms/100 ml in milk from 31 to 60 days, and to 5.10 micrograms/100 ml and 5.44 micrograms/100 ml in milk from 241 to 481 days. Seasonal and regional differences in EGF concentration were observed to some extent, but no clear tendency could be defined. These results suggest that EGF is an essential and fundamental factor for the growth of infants in the very early stages after delivery, because it was high only at the beginning of lactation and then it decreased.