The public health community has come to appreciate that a deeper understanding of the biology of human milk is essential to address ongoing and emerging questions about infant feeding practices. The critical pieces of that understanding are that 1) human milk is a complex biological system, a matrix of many interacting parts that is more than the sum of those parts, and 2) human milk production needs to be studied as an ecology that consists of inputs from the lactating parent, their breastfed baby, and their respective environments. The "Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)" Project was designed to examine this ecology as well as its functional implications for both the parent and infant and to explore ways in which this emerging knowledge can be expanded via a targeted research agenda and translated to support the community's efforts to ensure safe, efficacious, and context-specific infant feeding practices in the United States and globally. The five working groups of the BEGIN Project addressed the following themes: 1) parental inputs to human milk production and composition; 2) the components of human milk and the interactions of those components within this complex biological system; 3) infant inputs to the matrix, emphasizing the bidirectional relationships associated with the breastfeeding dyad; 4) the application of existing and new technologies and methodologies to study human milk as a complex biological system; and 5) approaches to translation and implementation of new knowledge to support safe and efficacious infant feeding practices.
Keywords: breastfeeding; breastfeeding parent–infant dyad; human milk; infant feeding practices.
Published by Elsevier Inc.