Chapter 6: Nutrition During Lactation

Human milk production relies on coordinated hormonal signaling in which prolactin stimulates the synthesis of milk components while oxytocin initiates the letdown reflex, enabling milk ejection and transfer to the infant. The composition of milk changes distinctly over time, beginning with colostrum—an isotonic fluid rich in protein and concentrated immune factors—and progressing to mature milk containing hundreds of bioactive compounds, including long-chain polyunsaturated fatty acids such as docosahexaenoic acid, whose concentration reflects maternal dietary intake. Lactating individuals transfer substantial health benefits to nursing infants, including dramatically reduced risk of infectious diseases such as otitis media, gastroenteritis, and necrotizing enterocolitis, with emerging evidence supporting lower incidence of chronic conditions including asthma and childhood obesity. Milk supply operates through a demand-driven autocrine feedback mechanism mediated by the protein Feedback Inhibitor of Lactation, which maintains homeostasis between milk removal and continued synthesis. Nutritional requirements during lactation increase substantially, with approximately 330 additional kilocalories needed daily during the first six months as energy mobilizes from maternal adipose tissue stores to support milk production. Public health infrastructure, including the Special Supplemental Nutrition Program for Women, Infants, and Children, the Surgeon General's Call to Action on Breastfeeding, and the Baby-Friendly Hospital Initiative, establishes comprehensive support systems across healthcare, workplace, and community environments to address structural barriers and increase rates of breastfeeding initiation and continuation.