We’ve been hearing it for a while now: Healthy bacteria in your intestines are crucial to good digestion and a strong immune system.  It’s no different when it comes to your baby.

Recent studies show that babies who are exclusively breastfed for the first six months of life have digestive systems that are perhaps better prepared for the transition to solid food that comes later. How so? It comes down to bacteria in your baby’s digestive tract.

“Breast milk is a living fluid,” says Wendy McHale, IBCLC and owner of Nurturing Lactation. She explains that breast milk isn’t sterile, and that it contains a lot of bacteria in it, meaning that breastfeeding moms are inoculating babies with all kinds of healthy bacteria. Healthy bacteria reside in a baby’s intestinal tract to help digest food, as well as aid in the development of the gut.
“Those micro-organisms set up a proper acidity level through the first six weeks,” she says, explaining that introducing formula too early can change acid levels, and consequently, bacteria.  This results in a smaller population of healthy bacteria, and a larger population of pathogenic, or disease-causing, bacteria.

Why does all this matter? McHale explains that our “guts” are actually the first line of defense in our immune systems — and one of the easiest places in the body for disease-causing material to enter. Because an infant’s intestines are not yet fully developed in those first few weeks of life, proper acidity and bacteria levels become all the more important.

Transitioning to Solids

All that healthy bacteria you helped your baby develop through breastfeeding might make it easier to digest solid foods according to researchers, but McHale reminds parents that breast milk is still the main source of nutrition for babies.

“Babies don’t absorb nutrients from food the way we do, even at six months,” she says.  Plus, she adds, babies don’t understand yet what food is.  When you put food on a tray for them, they tend to think of it as a new toy to explore. So in the beginning, food to babies is more about an exploration of the senses and learning socialization skills.

How to know when Baby is ready for solids? According to both McHale and the AAP, signs of readiness include:

  • Babies can sit on their own with little or no support
  • Babies can reach out, take food, and put it in their mouths accurately
  • Babies start gnawing on toys and more importantly, start to make chewing motions

If your baby pushes food out of his mouth when you offer a spoonful, he may not have the ability to use his tongue to move it to the back of his mouth, so wait another week or two.

If You Need to Supplement …

McHale acknowledges that there are times when supplementing breast milk is necessary.

“The first recommendation is mom’s milk, preferably at the breast,” she says, suggesting that new moms may want to first try offering the breast more often than the recommended every three hours.  The second option is breast milk expressed and given in another manner. A third option, commonly reserved for pre-term babies, is pasteurized human donor milk, given by doctor prescription.

If formula must be used, aim for hydrolyzed, which is broken down and gentler on the intestinal lining, according to the American Academy of Pediatrics (AAP). The final option is to use regular, cow’s milk based formula, which has been altered to make it more digestible and has additional iron.