Mother’s milk and brain development

Hi, my name is Monika Kaczmarek and I would like to tell you about the role of mother’s milk as potent modulator of brain development and health. We and other mammals, among other animals have one very unique characteristic. Just after we are born we need support of our mothers that nurse us with milk, produced and secreted by the mammary gland. But why couldn’t we, as newborns eat something else? Well, when mammals are born, they are devoid of nutrient system present in an egg, such as egg yolk. Moreover, mammalian’s underdeveloped young cannot seek out food independently.

That is why they need to get important nutrients and other bioactive components from mother’s milk Many milk-borne factors have ancient origin and are known to be important for sufficient development and grow of infants. Studies have further suggested that breast milk is an important determinant of adulthood health. Just how important mothers milk is can show some studies in animals and humans. Breast milk has long been acknowledged not only as an important source of nutrients, but also as an important modulator of immune system development of infants. It is due to the fact that milk is rich in immunoglobulins that provide the first source of adaptive immunity in a newborn’s.

Milk also contains immune system modulators, such as cytokines, Interleukin 1, 6 and growth factors, such as Transforming Growth Factor that help defend against infections. Other breast milk components, such glycans and oligosaccharides are recognized as a powerful modulators of infantile gastrointestinal microflora and thus immunity. It is well-known, for over 50 years, that milk contains hormones, that can participate in the development of acquired immune response in the pup. Studies in mice and rat showed that Prolactin present in milk can affect function of immune cells, such as macrophages, lymphocytes and natural killer cells. Mouse studies showed that maternal Tumor Necrosis Factor, through regulating milk chemokine levels influence hippocampal development in infants. Promoting adaptation to post-weaning environmental challenges and competition.

In details, mice of moms with reduced Tumor Necrosis Factor expression in the mammary gland had better spatial memory and spent less time in a freezing behavioral position during a challenge test. Human studies showed that predominant breast feeding for first 28 days is associated with larger deep nuclear gray matter volume and better academic achievements, working memory, motor functions at 7 years of age in very preterm infants. Hormones present in milk were also shown to be related to appropriate neuroendocrine and reproductive development. Prolactin may serve as one of the examples. In rats, experimentally reduced levels of Prolactin in maternal milk affect development of the pituitary cells of the pup, leading to increased plasma Prolactin levels, hyperprolactinemia, in the juvenile and adult stages.

In addition, female progeny showed irregular estrous cycles and disturbed estrogen secretion. Importantly, mother’s milk can also change the way how the baby acts. For example, when lactating mother is in a stress condition, her milk can contain stress hormones, such as cortisol, which directly affects an infant development. Studies on female rhesus monkey infants showed that cortisol levels in milk predicts cognitive and social behavior months later. Neonates suckled on milk containing higher levels of cortisol appeared to be less impulsive at the age of six months. To conclude, breastfeeding is crucial for neonatal development, influencing future health.

Milk contains not only nutritional substances, but also immune modulators, hormones, microorganisms and other important bioactive components, which affect among others development of immune, neuroendocrine and reproductive systems. What mother eats and how she is feeling matters, since it can influence the milk composition and thus development and health of offspring.