Human milk or breast milk is a primary source of nutrition available for newborns.
Breast milk has all the essential nutrients such as carbohydrates, protein, and fats as well as water to keep the baby hydrated and non-nutritive bioactive factors. Bioactive factors are elements that affect biological processes and have an impact on body function and ultimately health. These include anti infectious and anti-inflammatory agents, growth factors and prebiotics.
Bioactive factors in milk help carry immunological components to the baby’s body and help in optimal growth and development. An example would be vascular endothelial growth factor which is found in quite high concentrations in breast milk. Epidermal growth factor and Transforming growth factor are also present in human milk and help in healing damaged digestive tract in a neonate. Specially in premature babies, where, digestive tract may be underdeveloped, these growth factors provide protection against various gastrointestinal disorders.
Another important sugar present in human milk is lactose, the least variable component of breastmilk. It is also found to be higher in mothers having more milk supply. Human milk oligosaccharides(HMOs) are also found in breastmilk. These are not digested by the baby but along with bacteria, they help line the infant gut and act as decoy receptors and prevent disease causing bacteria from attaching, thereby protecting the baby against infections.
Colostrum which is the first milk produced by the mother, is rich in antibodies such as IgA, lactoferrin and leukocytes help activate natural defenses in baby’s digestive system and help them fight off attacks from various life threatening infections. Mature milk contains 0.9 to 1.2 g/dL of protein, 3.2 to 3.6 g/dL of fat, and 6.7 to 7.8 g/dL of lactose and provides energy of about 65-70 kcal/dL.
Fat is a quite variable component of breastmilk and is present in higher concentration in milk that comes later on during a feed (hindmilk) rather than milk coming in initial feed(foremilk). Foremilk is rich in water content thus satisfying the need of water in a baby and hind milk later on provides satiety.
Breastmilk also contains vitamins and minerals the concentration of which depends on the stores present in mother’s body. Vitamins and minerals play an important role for a variety of functions such as stimulating leukocytes and antibody production and in bone growth and brain development. That is why multivitamins are sometimes recommended for lactating mothers.
Milk composition changes diurnally, or may change over a few feeds and varies with every mother and across population. For example, even if the mother is ill, she is still encouraged to feed as whatever immunity builds up in her body passes through breastmilk to the baby or if a baby is born premature, breastmilk produced by the mother will contain elements necessary for the optimal growth of the baby and will be different as compared to breastmilk produced for a mature baby.
So, breast milk can be said to be a dynamic fluid as it changes composition according to the baby’s needs.  It is not merely nutrition but is much more and contributes to overall growth and development of the baby. This is what makes it unique for every baby and proves to be the ideal source of nutrition a new born baby can have.
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