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The Importance of B. Infantis in Infant Development

infant and mother


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Key Takeaways

  • Prebiotics and probiotics are crucial components to the development of healthy digestive systems in babies.
  • A recent study shows most babies born today are lacking these healthy bacteria.
  • Breastfeeding for at least 6 months helps colonize healthy gut bacteria, but supplements are available as well.

In the first 100 days after your baby is born, exposure to important probiotics can have a positive influence on their gut. This can have an impact on their life-long health. New research has shed light on particularly beneficial gut bacteria called Bifidobacterium longum subspecies infantis (B. infantis).

A study published in the journal Cell outlines how these beneficial bacteria can lead to healthy immune system development, which can then reduce the risk of allergies and autoimmune conditions in later years.

“We often see increased colic, fussiness, gas, diaper rash, and eczema in babies that don't possess enough of this healthy bacteria,” says Amna Husain, MD, FAAP, IBCLC, a board-certified pediatrician and founder of Pure Direct Pediatrics.

What Is B. Infantis?

According to Grace Clark-Hibbs, MDN, RDN, a registered dietitian nutritionist and gut health expert, B. infantis is the main bacterium found in the gut of breastfed infants.

“It is responsible for a variety of health benefits for the infant, including developing the immune system, protecting against inflammation, and strengthening the gut wall,” she says.

Study Details

The study, which included 268 babies from Sweden and California, used extensive blood testing to determine the level of B. infantis present in the bloodstream of each baby. Those with higher levels of these beneficial bacteria also had higher levels of anti-inflammatory markers.

By the same token, infants with low levels of B. infantis, which has the unique ability to metabolize beneficial sugars in breast milk called human milk oligosaccharides (HMOs), displayed higher levels of systemic inflammation and disordered development of their immune cells. 

Causes of Low Levels of B. Infantis

There are several factors, all of which occur at birth or shortly after, that influence an infant’s level of B. infantis. Sadly, estimates indicate that as many as 90% of infants don’t have adequate levels of these beneficial bacteria.

Grace Clark-Hibbs, MDA, RDN

Studies have shown that infants who were delivered via C-section and/or are not breastfed through at least the first 6 months of life are more likely to have a microbiome that is out of balance.

— Grace Clark-Hibbs, MDA, RDN

“The infant's microbiome is influenced by how they were delivered (vaginal vs. C-section), whether they are breastfed or not, and whether the mom was on antibiotics during pregnancy or while breastfeeding,” says Clark-Hibbs.

“Studies have shown that infants who were delivered via C-section and/or are not breastfed through at least the first 6 months of life are more likely to have a microbiome that is out of balance. All of these factors will lead to a large portion of infants having inadequate amounts of the crucial bacteria, B. infantis, in their guts," she explains.

Type of birth

Babies who are born vaginally are exposed to the healthy bacteria in their mom’s birth canal. In a C-section birth, this doesn’t happen, which can lead to lower lifetime levels of beneficial bacteria.

Method of feeding

Breastfed babies are naturally exposed to a host of prebiotics and probiotics that simply haven’t yet been added to infant formulas.

“Most infant formulas do not contain probiotics unless you buy a brand from a health food store—like a plant-based or non-dairy formula," says Heather Hanks, a nutritionist with Life Insurance Star. "Most of the time, parents and caregivers will need to add probiotics to formula as an additional supplement.”

An example of such a probiotic is Evivo, which Dr. Husain says is clinically proven to reduce potentially pathogenic gut bacteria by up to 80%.

Increased use of antibiotics

Antibiotic exposure at birth is another source of the issue. There’s a great deal of research indicating that antibiotic use destroys beneficial gut bacteria, and this occurs during childbirth as well. 

How to Help Establish a Healthy Microbiome


Breastfeeding an infant is the best way to ensure they get adequate levels of B. infantis. The bacteria thrive on the sugars present in human breast milk, and thus will increase levels in the infant’s body. If breastfeeding isn’t possible and donor milk also isn’t feasible, parents can consider probiotic and prebiotic supplementation.

Amna Husain, MD, FAAP, IBCLC

I recommend a probiotic that contains B. infantis EVC001, which has been shown to be well tolerated in breastfed infants. This can help to efficiently colonize the infant gut, resulting in a significant reduction of pathogenic bacteria and enteric inflammation.

— Amna Husain, MD, FAAP, IBCLC

“I recommend a probiotic that contains B. infantis EVC001, which has been shown to be well tolerated in breastfed infants,” says Dr. Husain. “This can help to efficiently colonize the infant gut, resulting in a significant reduction of pathogenic bacteria and enteric inflammation.”

However, it’s important to note that parents should always consult with their baby’s pediatrician before adding anything to baby’s diet. The risk of possible allergens is the biggest issue. 

What This Means For You

While breastfeeding does offer complete nutrition, which includes prebiotics and probiotics like B. infantis, the most important thing is that your baby is fed. If breastfeeding isn’t possible, probiotic supplements can greatly enhance a baby’s lifelong immune response. The benefits could be similar to those gained through human breast milk. Be sure to talk to your doctor about these supplements to determine if they are right for your baby.

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Article Sources
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  1. Henrick BM, Rodriguez L, Lakshmikanth T, et al. Bifidobacteria-mediated immune system imprinting early in lifeCell. Published online June 17, 2021. doi:10.1016/j.cell.2021.05.030

  2. Casaburi G, Duar RM, Brown H, et al. Metagenomic insights of the infant microbiome community structure and function across multiple sites in the United States. Sci Rep. 2021;11(1):1472. doi:10.1038/s41598-020-80583-9

  3. Frese SA, Hutton AA, Contreras LN, et al. Persistence of supplemented Bifidobacterium longum subsp. infantis EVC001 in breastfed infants. mSphere. 2017;2(6). doi:10.1128/mSphere.00501-17