My Bacteria Is Better Than Yours

Breast milk bacteria more protective against germs and infection than formula

(RxWiki News) Everyone's got billions of little critters hanging out in their gut. They're helpful little critters — they aid the digestive and immune systems. But what you eat changes what they are.

And a recent study has found that there's an especially significant difference between the collection of critters in breastfed babies and the collection in formula-fed babies.

"Breastfeed your baby at least 6 months."

The study, led by William Parker, PhD, an associate professor of surgery at Duke University Medical Center, looked at the different types of bacteria that grows in different kinds of nutrition for babies.

Dr. Parker and his team grew two different strains of E. coli bacteria in donated breast milk, whole cow's milk and in three popular brands of milk-based or soy-based infant formula.

They also grew the E. coli in a solution of "secretory immunoglobulin A" (SIgA). SIgA is a type of antibody — an immune cell that a body uses to fight disease — that exists in breast milk and helps a baby's immune system develop.

E. coli was used because it's one of the first critters to move into a newborn's gut. These were different strains of E. coli than the ones that cause food poisoning.

The bacteria began to multiply in all the tested solutions, but it didn't grow the same way in all of them.

In the sample of breast milk, the bacteria grouped together into thin layers that can protect against infection and germs.

The bacteria grew like crazy in the infant formula samples and in the cow's milk also, but the critters struck out on their own independently in these sample.

They didn't stick together to form these shields of "biofilm."

The bacteria in the SIgA sometimes grouped together and sometimes didn't. This implied that SIgA by itself doesn't lead the bacteria to band together like it did in the breast milk.

The researchers don't know whether other types of bacteria do the same thing in breast milk compared to cow's milk or infant formula.

But the actions of E. coli in these samples may explain why a mom's breast milk has so many immune system benefits for babies.



Past studies have already found a long list of helpful effects from breastfeeding. These include lower rates of diarrhea, flu and respiratory infections among babies.

Being breastfed also reduces the risk that a baby will develop allergies, type 1 diabetes, multiple sclerosis and various other conditions later in life.


Dr. Panayotti is the co-director of the newborn nursery for Duke Children's and Duke Primary Care.

"We know that babies who receive breast milk have better outcomes in many ways, and mother who breast feed also have improved health outcomes, including decreased risks of cancer," she said. "Whenever possible, promoting breast feeding is the absolute best option for mom and baby."

The study was published in the journal Current Nutrition & Food Science. The research was funded by the Fannie E. Rippel Foundation and a Howard Hughes Medical Institute fellowship. The authors declared no conflicts of interest.

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Review Date: 
August 28, 2012