Infant factors that impact the ecology of human milk secretion and composition—a report from “Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)” Working Group 3

Parental factors that impact the ecology of human mammary development, milk secretion, and milk composition—a report from “Breastmilk Ecology: Genesis of Infant Nutrition (BEGIN)” Working Group 1

“…Homeorhesis is the coordinated control of nutrient metabolism in the breastfeeding parent and includes the adaptation of many organs to support the availability of nutrients for milk synthesis [ 54 ]. To evaluate homeorhesis in humans it is necessary to know the mass uptake of milk constituents into and transfer out of the gland in addition to concentrations in plasma, mammary cells, and milk; as a priority, the volume of milk transfer to the infant must also be measured, a much more difficult undertaking in lactating parents as outlined in the report of WG 3 [ 55 ]. To summarize here, the only two accurate methods of measuring milk transfer to the breastfeeding infant are test-weighing before and after each feed for ≥24 h [ 56 ] and deuterium dilution [ 57 , 58 ].…”

“…Further, the consumption of probiotic foods can lead to the transfer of bacteria into the human milk microbiota [ 81 ]. The interaction of HMOs with the infant microbiome is considered in the report of WG 2 [ 64 ], and the role of the infant microbiome in infant development is considered in the report of WG 3 [ 55 ].…”

“…This dialog includes both uni- and bidirectional components ( Figure 2 ), the most obvious of which is the transfer of the lactating parent’s milk, with its complex array of nutritional, immunological, and other components, to the nursing infant. The infant’s feeding style in general (described in detail in the report of WG 3 [ 55 ]), as well as their mental and physical state during each nursing episode, are additional unidirectional components, as is the health status and mental state of the lactating parent. These elements create subsequent responses in both the lactating parent and infant that affect the brain in both individuals.…”

“…The need for research in this area is illustrated by the finding that tetrahydrocannabinol and cannabidiol accumulate to significant concentrations in breastmilk relative to those in plasma [ 197 ]. The little that is known about their effects on lactation and the recipient infant are summarized by WG 3 [ 55 ], and research approaches are summarized by WG 5 [ 198 ]. Alcohol, particularly in disabling alcoholism, has mostly been studied for its transfer into breastmilk and its effects on the infant; this topic is well covered by WG 3 [ 55 ].…”

“…The little that is known about their effects on lactation and the recipient infant are summarized by WG 3 [ 55 ], and research approaches are summarized by WG 5 [ 198 ]. Alcohol, particularly in disabling alcoholism, has mostly been studied for its transfer into breastmilk and its effects on the infant; this topic is well covered by WG 3 [ 55 ]. However, there are questions regarding its addictive use in the lactating parent because it is a neurotoxin that significantly changes parental behavior as well as depressing myometrial/myoepithelial function.…”