LLL Today #3 – The Science Behind the Benefits of Human Milk

La Leche League ( LLL) Leaders support breastfeeding mothers by giving information and mother-to-mother guidance . Leaders advocate for breastfeeding through philosophies, one of which says, “Human Milk is the natural food for babies, uniquely meeting their changing needs[1].”One way to help is to bridge the knowledge gaps. Scientific information can provide support and validation to get breastfeeding to a good start. Using science, leaders can advocate for the infant and empower mothers to understand the abilities of human milk to help infants’ development after birth. When nursing mothers understand details that bring life-long benefits to a newborn, mothers are more likely to make informed decisions on their breastfeeding journey. Science asserts two essential roles of human milk that support infants. First, human breast milk impacts an infant’s gut, bringing life-long benefits. Second, breastmilk can dynamically change to meet the infant’s unique needs.

The Science

Human milk is the key to supporting the immune process’s maturation, activation, and growth. Support for newborns comes through the nutritional and functional processes in the gut. These processes help the newborn’s immature gut establish microbiota (living organisms in the gut) to fight infections. Microbiota then promotes gastrointestinal mucosa and dietary strength.

Essential components like maternal antibodies (immune cells) are transferred from the mother via the placenta during the third trimester of the pregnancy. These include the following:

  •     IgA: fight illness and promotes pathogen clearance
  •     IgG: prevent infections
  •     IgM:  recognize infections and aids pathogen clearance
  •     Lysosomal enzymes: break down bacterial membranes to make it easy for IgA and IgM for pathogen clearance
  •   Growth factors and Cytokines: build up inflammatory response to infection

Together, these create a solid intestinal microbiota that promotes the development of the newborn gut and a robust immune system[2]. At birth, babies are ready to absorb colostrum, the first milk rich in contents that aid the gastrointestinal tract by lining it with immunological factors. A highly permeable gut allows human milk to flow thoroughly to absorb nutrients and immune properties. These physiological trajectories close intestinal gaps around twenty-two weeks after birth[3]. At four to six months, the infant is ready for the introduction to complementary food. By this time, the gut has matured and is less permeable to viruses and bacteria, leading to fewer infections. Over the years, the benefits of breastfeeding include decreased risk for asthma, allergies, otitis media, gastrointestinal/respiratory infections, heart disease, obesity, and type 2 diabetes. These are all evidence of a strong gut and immunity process.

In premature babies, these nutritional and functional components are essential for survival. Babies born under 32 weeks’ gestation are at the highest risk for developing life-threatening conditions such as necrotizing enterocolitis (NE), growth failure, short bowel syndrome, and delays in neurodevelopment. This is primarily because of the underdeveloped gut and missed opportunity for immune cell transfer through the placenta at the third-trimester benchmark[4]. In these circumstances, colostrum and human milk are essential, as it is known that human milk has the natural ability to modify and regulate on demand. When a premature baby is given human milk, the baby establishes a healthy foundation to minimize the risk associated with the vulnerability of being born too early. It contributes to the overall healthy development of the child. It gives premature infants the best start to life outside of the womb.


Human milk is the key to a healthy newborn and development. Human milk impacts the newborn’s gut and starts a process that brings lifetime advantages. Leaders play an essential role in filling the knowledge gaps to empower mothers. Science sparks curiosity, a critical motivator to continue breastfeeding. Most importantly, it encourages them to make informed decisions about their journey, their baby, and themselves.


[1] “Philosophy – La Leche League International.” https://llli.org/about/philosophy/. Accessed 30 Mar. 2023.

[2] “The Immature Gut Barrier and Its Importance in Establishing ….” 11 May. 2020, https://www.frontiersin.org/articles/10.3389/fimmu.2020.01153/full. Accessed 30 Mar. 2023.

[3] “The Immature Gut Barrier and Its Importance in Establishing ….” 11 May. 2020, https://www.frontiersin.org/articles/10.3389/fimmu.2020.01153/full. Accessed 30 Mar. 2023.

[4] “Maternal breastmilk, infant gut microbiome … – Wiley Online Library.” 15 Aug. 2020, https://onlinelibrary.wiley.com/doi/full/10.1111/apa.15534. Accessed 30 Mar. 2023.

Lola Ravid, LLL Leader