Found this on Rixa's blog. So very cool! Just one of the many things that formula will never be able to replicate, no matter how "close to breastmilk" it claims to be.
How Breastfeeding Transfers Immunity to Babies
ScienceDaily (Oct. 27, 2008) — A BYU-Harvard-Stanford research team has identified a molecule that is key to mothers’ ability to pass along immunity to intestinal infections to their babies through breast milk.
The study highlights an amazing change that takes place in a mother’s body when she begins producing breast milk. For years before her pregnancy, cells that produce antibodies against intestinal infections travel around her circulatory system as if it were a highway and regularly take an “off-ramp” to her intestine. There they stand ready to defend against infections such as cholera or rotavirus. But once she begins lactating, some of these same antibody-producing cells suddenly begin taking a different “off-ramp,” so to speak, that leads to the mammary glands. That way, when her baby nurses, the antibodies go straight to his intestine and offer protection while he builds up his own immunity...
Read the rest of the article here.