IBCLC Exam 2025 – 400 Free Practice Questions to Pass the Exam

The primary role of secretory IgA (sIgA) found in human milk is to protect against infections. Secretory IgA is a type of antibody that plays a crucial role in the immune defense of the infant. It is responsible for providing passive immunity by coating pathogens such as bacteria and viruses, preventing them from adhering to the mucosal surfaces of the gastrointestinal tract and respiratory system. This action helps to neutralize and eliminate potential threats, thereby reducing the risk of gastrointestinal infections and other illnesses in breastfed infants.

Unlike other immunoglobulins, secretory IgA is specifically adapted to function in mucosal areas, as it is resistant to degradation by enzymes and can effectively act at the sites where infections typically enter the body. The presence of sIgA in human milk is particularly important during the early months of an infant's life, when their own immune system is still developing.

While the other options present important aspects of infant health and nutrition, secretory IgA's primary function centers on immune protection, making it a vital component of the immunological benefit that breastfeeding provides.