Immunoglobulins: All types of immunoglobulins are found in human milk. The highest concentration is found in colostrum, the pre-milk that is only available from the breast the first three to five days of the baby’s life. Secretory IGA, a type of immunoglobulin that protects the ears, nose, throat, and the GI tract, is found in high amounts in breast milk throughout the first year. Breast milk levels of IGA against specific viruses and bacteria increase in response to a maternal exposure to these organisms.
Lactoferrin: Lactoferrin is an iron-binding protein that is found in human milk, but is not available in formulas. It limits the availability of iron to bacteria in the intestines, and alters which healthy bacteria will thrive in the gut. It is found in the highest concentrations in colostrum, but persists throughout the entire first year. It has a direct antibiotic effect on bacteria such as staphylococci and E. coli.
Lysozyme: Human breast milk contains lysozyme (a potent digestive ingredient) at a level thirty times higher than in any formula. While other components of breast milk vary widely between well-nourished and poorly nourished mothers, the amount of lysozyme is conserved, suggesting that it is very important. It has a strong influence on the type of bacteria that inhabit the intestinal tract.
Growth Factors: Human breast milk specifically encourages the growth of lactobacillaceae, which are helpful bacteria that can inhibit many of the disease-causing gram-negative bacteria and parasites. There is a striking difference between the bacteria found in the guts of breast and formula-fed infants. Breast-fed infants have a level of lactobacillus that is typically 10 times greater than that of formula-fed infants.
Allergic factors: The cows’ milk protein used in most formulas is a foreign protein. When babies are exposed to non-human milk, they actually develop antibodies to the foreign protein.
Carnitine: While carnitine is present in both breast milk and formula, the carnitine in breast milk has higher bioavailability. Breast-fed babies have significantly higher carnitine levels than their counterparts. Carnitine is necessary to make use of fatty acids as an energy source.
DHA & ARA: The main long-chain fatty acids found in human milk are still not present in many formulas in the United States. These lipids are important structural components, particularly in the substance of the brain and the retina. Significantly different amounts of these ingredients have been found in the brains and retinas of breast-fed versus formula-fed infants.