The Good Stuff: Breastfeeding Delivers Beneficial Bacteria to Baby

Breastfeeding is the ultimate in farm-to-table dining. It is sustenance prepared just for the baby and delivered with a very personal touch. Along with bonding, breastfeeding provides powerful protection to infants and young children in the form of beneficial bacteria, hormones, vitamins, protein, sugar, and antibodies manufactured on site to support infant health.

The idea that breastmilk is bioactive and full of good stuff for babies is not new. After all, breastfeeding is as old as humankind. Both the World Health Organization and the American Academy of Pediatrics recommend breastmilk exclusively for the first six months of life, and after that for as long as mom and baby desire.

The Good Stuff: Breastfeeding Delivers Beneficial Bacteria to Baby — *Image by Bob Whitehead/Flickr*

According to the most recent statistics available from the Centers for Disease Control and Prevention (CDC), breastfeeding is continuing to gain popularity in this country. Approximately four out of five women start out breastfeeding their babies after birth. More than half are still breastfeeding after six months, and about one-third are still going strong at 12 months.

New research published in the journal JAMA Pediatrics took an up-close look at a major benefit of breastfeeding — the transfer of beneficial bacteria from mom to baby to establish healthy communities of bacteria for life — in a newborn baby.

Babies, Breasts & Bacteria

Surprisingly, breastfeeding can be a contentious topic. Some people are offended when women breastfeed in public. Others note that formula contains all the necessary nutrition to raise healthy infants, while many feel breast is best — wherever the need arises.

As the most basic form of human nurturance, breastfeeding is rooted in culture, child-rearing, tradition, and science. This recent study, headed by scientists at UCLA, is the largest research to date to investigate the transfer of beneficial bacteria from mom to baby. The study followed 107 healthy mother-infant pairs from January 2010 through February 2015. The study did not focus on bacterial development in strictly formula-fed babies, nor was its aim to compare breastfeeding to formula feeding.

In a press release, Grace Aldrovandi, senior author and professor of pediatrics and chief of infectious diseases at UCLA Children's Hospital, said:

Breast milk is this amazing liquid that, through millions of years of evolution, has evolved to make babies healthy, particularly their immune systems. Our research identifies a new mechanism that contributes to building stronger, healthier babies.

The researchers collected samples of breastmilk, swabs of bacteria from breast skin, and infant stool samples from diapers. The researchers extracted DNA and sequenced it, followed by statistical analysis.

Infants in the study were roughly equal over gender. About 66% were Hispanic/Latino, and about 65% were born via vaginal delivery. The types and numbers of bacteria that developed in growing children were similar regardless of gender, ethnic background, or vaginal or Caesarean delivery.

Findings of the study include:

The infant microbiome was almost 40% "seeded" by bacterial communities in breastmilk.
As expected, there were distinct common bacterial communities identified between unique mother and baby pairs.
There was no difference in the bacterial composition between samples from right and left breasts.
The diversity of breast milk bacterial communities remained constant during the first year of life after increasing in the first six months of life.
Bacterial diversity in infant poop samples increased with age, as could be expected.
Bacteria in the samples were bacteria commonly found in the human gut, including Proteobacteria (found mostly in breastmilk), Firmicutes (located on the skin), and Actinobacteria (the dominant bacteria in infant stool).
Children primarily fed breastmilk received more bacteria than those introduced early (at around four months) to solid foods.
The study notes breastmilk "contains bacteria with … high abundance in gene families associated with membrane transport and carbohydrate, amino acid, and energy metabolism."

Of the importance of this bacterial inheritance from mom to baby, the authors wrote:

Early life may represent a critical window for bacterial imprinting of breast milk bacteria leading to nonrandom community assembly. Breast milk bacteria that seed the gut first influence and select for bacteria that follow, leaving a footprint that can be detected even in adulthood.

In reporting on infants that gradually received formula over time, the authors found that the introduction of formula did not change the bacterial pattern of the infant microbiome already established, but along with solid food, pushes the microbiome more quickly into more adult-like bacterial communities. For these reasons, the authors recommend to breastfeed exclusively for six months, and continue at least a year, if not longer.

Researchers cite earlier studies that document differences between stool microbiota of breastfed and nonbreastfed babies that persist into adulthood. Breastfeeding is found to confer protections against asthma, allergies, and certain chronic diseases like diabetes and obesity. This study confirms the transmission of that good protective stuff between the mature immune system of mom and the developing newborn through breast milk.

We're appreciating more and more how these bacterial communities, particularly in the intestine, help guard against the bad guys. We know from animal model systems that if you get good bacteria in your gut early in life, you're more likely to be healthy.

— Grace Aldrovandi, UCLA Children's Hospital