The Problem:  

All organs of newborns are under development, including the intestine and its mucosal barrier.  Fresh mother's milk requires no pancreatic digestive enzymes.  It comprises Mom's stem and immune cells, lipid droplets, proteins, and other biomolecules that require no digestion.  In contrast, man-made formula (or any other food) requires digestion by the infants' pancreatic enzymes, just like in the mature intestines of older children and adults.  

Here is the problem:  If pancreatic digestive enzymes are released when the mucosal barrier in the intestine is not yet fully developed, the infant has no protection against its digestive enzymes.  

For example, any baby formula (even if just supplemented) requires pancreatic digestive enzymes for absorption by the intestinal epithelium.  Premature feeding of formula, when the intestinal barrier is not fully developed, can be a mechanism for necrotizing enterocolitis or organ injury in autism.  

Furthermore, pancreatic lipase generates cytotoxic mediators from baby formula or stored milk by generating unbound free fatty acid. Unbound free fatty acids are cytotoxic for cells, including the epithelium in the intestine.   

Epidemiology suggests that the longer an infant is breastfed, the lower the incidence of gastrointestinal complications.  

A Research Opportunity:  

There is a need for bioengineering to design tests that allow families to reliably evaluate and determine whether their baby's intestine has a mucosal barrier that does not allow digestive enzymes or toxins derived from them to leak into the circulation.  

Take Home Message:

An infant's intestine is under development, just like other organs.  

Mom's milk needs digestion digestion.  

Infant formula, even as a supplement, requires pancreatic digestive enzymes for digestion and an intestine with a mature mucosal barrier.   

An infant may not have the protection mechanisms for digestion, which may expose them to Autodigestion.