Intestinal Health

The Breastfeeding Book: Everything You Need to Know About Nursing Your Child
by Martha Sears, R. N., William Sears, M. D.

(Page 4 of 9)

Breast milk is known as the “easy in-easy out” food. It's easier to digest and makes easier-to-pass stools. In fact, breast milk contains enzymes that help babies digest their meals from the breast. Whey, the predominant protein in breast milk, forms an intestines-friendly, soft, easy-to-digest curd, unlike the rubbery, harder-to-digest casein curd formed in the digestion of most formulas. Tiny tummies like breast milk. It's digested more quickly and is less likely to come back up. It doesn't leave permanent stains on clothes, either.

While all babies spit up a bit, some regurgitate excessive amounts of milk because of a condition called gastroesophageal reflux (GER). Normally, the circular band of muscle where the esophagus joins the stomach acts like a one-way valve, keeping milk, food, and stomach acids from backing up into the esophagus when the stomach contracts. When it doesn't do its job, acids enter the esophagus, resulting in an irritation that adults would call heartburn. In many infants, it takes six months to a year for this muscle to mature enough to prevent this regurgitation or reflux. GER occurs less often in breastfed infants because breast milk is emptied twice as fast from the stomach and because breastfed babies tend to eat smaller meals that are more appropriate in size. It's less likely to be regurgitated than slow-to-digest formula with its tough casein curds.

Breast milk is friendly to immature intestines. The cells of the intestinal lining are tightly packed together so that potential allergens cannot seep through into the bloodstream. But in the early months, the lining of the baby's immature intestines is more like a sieve, allowing potential allergens to get through, which sets the infant and child up for allergies and infections. Breast milk contains a special protein called immunoglobulin A (IgA), which acts like a protective sealant in the digestive tract. Allergens and germs can't get through as easily. Breast milk also contains a special substance called epidermal growth factor (EGF), which promotes the growth of the cells lining baby's intestines as well as other surface cells, such as the cells of the skin.

Since formula does not provide this protective coating, it's easier for allergens to pass through into the bloodstream, a condition known as the leaky gut syndrome. This is part of the reason for the higher incidence of allergies in formula-fed infants. By the second half of the first year, the intestinal lining matures enough to prevent these leaks (a developmental process called closure).

Breast milk produces caregiver-friendly stools. Unlike the stinky stools of a formula-fed baby, the stools of a breastfed infant have a not unpleasant buttermilk-like odor. In watching moms and dads change the diapers of a formula-fed baby, we have noticed that their facial expressions generally reflect reactions that range from mild aversion to downright disgust. Because the odor of breast-milk stools is not offensive to most parents, changing the diaper of a breastfed infant is not an unpleasant task (which is fortunate, because younger breastfed babies have several bowel movements a day). When the baby looks at the face of the diaper-changing caregiver and sees happiness rather than disgust, he picks up a good message about himself - perhaps a perk for building self-esteem.

Breast milk helps better bugs live in the bowels. Intestines are healthier when you can keep the right bugs in the bowels, and that's exactly what breast milk does. The intestines contain healthful as well as potentially harmful bacteria. The healthful bacteria, known as bifidus bacteria, do good things for the body in return for a warm place to live. They manufacture vitamins and nutrients and keep the harmful bacteria in check. Breast milk promotes the growth of healthful bacteria and inhibits the growth of harmful ones. The high level of lactose in breast milk particularly encourages the growth of the healthful resident bacteria Lactobacillus bifidus.

© 2000 by Martha Sears, R.N., and William Sears, M.D.

About the Author

Martha Sears is a registered nurse, childbirth educator, and breastfeeding consultant.

William Sears, M.D., received his pediatric training at Harvard Medical School's Children's Hospital and Toronto's Hospital for Sick Children. He has practiced as a pediatrician for more than thirty years.