Now, researchers at Duke University have found something else breast milk offers that baby formulas don't.
Even when they're away from home, Carleen McKenna is committed to breastfeeding 4-month-old daughter, Elle, whenever she's hungry.
“I know that it's the perfect nutrition for her,” she said. “So the composition of the breast milk changes as she changes and it adjusts to her needs.”
The antibodies in breast milk protect babies from a variety of illnesses. The reasons how aren't fully known, though Duke’s William Parker and his research team found one answer.
“What we're finding out is that breast milk is feeding the baby's bacteria in such a way that the bacteria grow in a particular pattern,” he said.
Using other sources of nutrition, Parker says, bacteria travels randomly in the body. But with breast milk, it's concentrated in layers growing along the baby's intestinal tract.
“When you use an infant formula, you just don't get that,” he said.
“The bacteria are important to train the baby's immune system,” Parker said. “The idea here is the mother's milk is very important for how the bacteria develop and probably, therefore, important for how the baby develops.”
McKenna appreciates all the science behind it, but she just enjoys bonding with Elle.
“(It’s) just the sweetest time that we have together,” she said. “I love every second of breastfeeding, even when she wakes up in the middle of the night to eat and I'm exhausted.”
The WakeMed Mother's Milk Bank is an option for mothers who can't breastfeed.