Breastfeed infants exclusively for immune development
Dr. Berg frames breastfeeding as the single most powerful immune intervention for newborns, far superior to any supplement or sterile environment. He explains that the infant's immune system is essentially incomplete at birth and must be educated. Mother's milk provides both immediate protection and the substrate for a healthy microbiome. He contrasts this with modern fears of germs, emphasizing that the other half of immune development comes from controlled exposure to pathogens—allowing the child to experience fevers and minor illnesses rather than over-sterilizing their environment. For those who cannot breastfeed, he mentions community resources like La Leche League as a potential alternative to obtain breast milk.
Breast milk contains immunoglobulins, immune cells, and cytokines that directly provide passive immunity. It also seeds the infant gut with beneficial bacteria (probiotics) that train the developing immune system. Dr. Berg states it provides 'half of your mother's immune system', highlighting the passive transfer of antibodies and memory cells.
The absolute, hands down, most powerful thing you can do for an infant is make sure that infant is fed mother's milk... you're not only getting probiotics, you're getting half of your mother's immune system.

