The Total Amino Acid Profile of Human Milk is Stable Over the First Year of Lactation and Consistent Across Geographical Populations: a GEHM Study

Abstract

The amino acid composition of human milk is thought to be critical in the development of breastfed infants. Part of the Global Exploration of Human Milk (GEHM) study examines variability in amino acid profiles over the course of lactation, both between individual mothers and across geographical populations. Total and free amino acid profiles, determined using specialized ion exchange chromatography followed by post column derivitization, are reported for longitudinal samples collected from three global cohorts (Mexico, China, and USA) at 4, 13, 26, and 52 weeks lactation. This study focused on utilization of rigorously controlled sample collection techniques as well as statistically monitored process control during analysis to ensure the accuracy of generated results. Although the amino acid profiles of human milk have been reported previously, these extra control measures as well as the integration of numerous samples from different geographical populations provides additional insights into amino acids in human milk. While the free amino acid profiles exhibit higher variability amongst individuals, these findings suggest that the total amino acid profiles remain remarkably consistent even when investigated in distinct geographical locations, amongst multiple donors, and across lactation. This characteristic pattern, observed in all amino acids, can be illustrated by the essential amino acid Threonine (Thr), which has a variability of 55% for free Thr and 4% for total Thr. Support for this research was provided by Mead Johnson Pediatric Nutrition Institute.