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Bioactive content

In addition to the nutritional benefits of breastmilk, breast milk also provides enzymes, antibodies, and other substances that support the infant's growth and development. The bioactive makeup of breastmilk also changes based on the needs of the infant; for example, when an infant is recovering from an upper respiratory infection, local signaling allows for increased passage of immune cells and proteins to aid the infant's immune system.

Produced during pregnancy and the first days after childbirth, colostrum is easy to digest and has laxative properties that help the infant to pass early stools. This aids in the excretion of excess bilirubin, which helps to prevent jaundice. Colostrum also helps to seal the infants gastrointestinal tract from foreign substances and germs, which may sensitize the baby to foods that the mother has eaten and decrease the risk of diarrheal illness. Although the baby has received some antibodies (IgG) through the placenta, colostrum contains a substance which is new to the newborn, secretory immunoglobulin A (IgA). IgA works to attack germs in the mucous membranes of the throat, lungs, and intestines, which are most likely to come under attack from germs. Additionally, colostrum and mature breast milk contain many antioxidant and anti-inflammatory enzymes and proteins that decrease the risk of gastrointestinal allergies to food, respiratory allergies to air particles like pollen, and other atopic diseases, such as asthma and eczema.