Breastfeeding can protect your baby from developing allergies

Babies who are fed a formula based on cow's milk or soy tend to have more allergic reactions than breastfed babies.
Scientists think that immune factors such as secretory IgA (only available in breast milk) help prevent allergic reactions to food by providing a layer of protection to a baby's intestinal tract. Without this protection, inflammation can develop and the wall of the intestine can become "leaky." This allows undigested proteins to cross the gut where they can cause an allergic reaction and other health problems.
Babies who are fed formula rather than breast milk don't get this layer of protection, so they're more vulnerable to inflammation, allergies, and other eventual health issues.