Breast Milk and B. Infantis: Nature’s Favorite Probiotic

Breastfeeding and probiotics

We can’t help but extol the virtues of breast milk. A perfect recipe of vitamins, minerals, antibodies, lactoferrin, immune and growth factors, fatty acids, and much more—and a composition that miraculously changes based on the time of day and on your baby’s unique nutritional and immune system needs—breast milk provides the ideal and ever-evolving nourishment for your infant.

But did you know that what’s under the microscope may be responsible for some of breast milk’s most beneficial properties? Breast milk is full of good bacteria that provide crucial functions to support your baby’s growth and development, and specifically, a balanced gut microbiome is one of the key factors for the proper development of your baby’s budding immune system.

Since 80% of our immune system resides in the gut, our bacteria play a starring role as they work with our own cells to modulate and balance our immune responses. And how your baby’s immune system develops in those critical first few months can determine their immune system function for the rest of their life1.

From training the immune system cells to respond correctly and providing protection from harmful bacteria to improving digestion and nutrient absorption, friendly flora in breast milk are essential to your infant’s long-term health and immunity.

You see, before birth, babies encounter small amounts of bacteria from the placenta, but it’s the journey through the birth canal that inoculates them with the tremendous amount of beneficial microbes they need to jump start their microbial life outside of the womb. And then comes breastfeeding, nature’s slow and steady lifeline of goodness. Researchers estimate that infants ingest anywhere from 10 to 100 million bacterial cells every day through breast milk alone, representing hundreds of different species2.

Here’s where it gets fascinating: we know that breastmilk is the best source of food and sustenance for children and that it supplies them with the probiotic bacteria they need, but what we’ve recently learned is that these friendly bacteria are so essential to your baby’s health that breast milk also contains the food your baby’s flora need to thrive!

Microbes and the Sugar Connection

Scientists have identified more than two hundred different sugars in breast milk, called human milk oligosaccharides (HMOs); in fact, these super sugars are the third most abundant component of breast milk3. HMOs are completely indigestible by humans, which begs the question—why would a mom’s body expend so much energy producing HMOs when they don’t offer any direct nutrition to her baby?

Scientists were puzzled with this question for years—until they began to understand the microscopic world of the gut microbiome. First, they noticed that HMOs seem to perform as decoys for the bad guy bacteria. You see, undesirable bacteria like to latch on to sugar molecules on our intestinal cells, but HMOs bear a striking resemblance to the sugars. Bad guy bacteria get confused and attach to HMOs in baby’s gut instead, leaving vulnerable intestinal cells alone.

In addition to putting on a facade, HMOs fulfill a critical role as prebiotics, or food for microbes. Prebiotics are to probiotics what fertilizer is to a garden—they help good bacteria grow and thrive. Scientists used to believe that HMOs in breast milk nourished all of a baby’s gut bacteria, but it turns out that the aptly named Bifidobacterium infantis—a subspecies of Bifidobacterium Longum—is the only strain that can fully break down and utilize the sugars.

So, we know that the HMOs’ primary purpose is to feed beneficial bacteria, but why would breast milk evolve to selectively feed this specific strain?

5 Big Benefits of Bifidobacterium Infantis

B. infantis boasts a plethora of special functions that could possibly explain why nature seems to have deemed this strain as the most important, foundational strain for human health.

Let’s have a look at some of the crucial life-supporting services this friendly flora provides:

1. Produces short-chain fatty acids. As B. infantis digests HMOs, it releases short-chain fatty acids like acetic acid that nourish intestinal cells. Not only can acetic acid keep yeast and fungus growth under control, but it also provides a source of energy for growing bodies.

2. Supports gut integrity. Babies are born with open guts, meaning that they have spaces between their intestinal cells through which toxins and undesirable bacteria can slip into the bloodstream. B. infantis signals a baby’s gut cells to produce proteins that fill the gaps, thus reducing permeability and possible health issues4.

3. Crowds out bad guys. Because B. infantis devours HMOs—and because HMOs are so plentiful in breast milk—breastfed babies have gut microbiomes dominated by this mighty microbe. B. infantis outcompetes other bacteria and takes up space, leaving little room for the bad guys to settle in and cause problems.

4. Releases sialic acid. Sialic acid is an essential nutrient for brain development in infants. Unlike most other bacteria in the gut, B. infantis ferments and releases sialic acid as it consumes HMOs5.

5. Produces folate. B. infantis produces folate (aka vitamin B9), necessary for the production of red blood cells and baby’s healthy growth and development6. Folate also supports DNA synthesis and repair.

B. infantis certainly lives up to its name when it comes to supporting your baby’s health. So, how do you make sure you have plenty of this advantageous microbe to go around?

Breastfeeding is Best for Baby’s Gut Health

First and foremost, when it comes to optimal health for your baby, breastfeed for as long as you can! Nursing exclusively for the first six months sets your baby up for a lifetime of good health by giving them the perfect nutrition for their growing body, including plenty of the good guy probiotics.

And make sure to take care of you own microbial health! After all, you can only pass on beneficial bacteria to your little one if your own microbiome is healthy and balanced. Begin to live a gut healthy life by following these three simple steps:

• Take probiotics! Support your microbiome before, during, and after pregnancy with a high-quality probiotic formula like Hyperbiotics PRO-Moms that includes B. infantis for your breastfeeding baby.

• Stay away from probiotic-killers. Processed foods, antibiotics in food and as medicine, certain medications, and even antibacterial cleaners can all wipe out your population of probiotics. And, guess what? If your beneficial microbes are in low supply, your baby’s microbiome will suffer as well.

• Focus on prebiotics. Just as HMOs in breast milk provide food for the microbes in your baby’s gut, you need to provide food for your own bacteria. Focus on a diet high in plant-based foods like asparagus, Jerusalem artichoke, bananas, dandelion greens, and garlic to nourish your friendly flora.

And finally, when you’re up in the wee hours of the night with a suckling little one, remember that breast milk is nature’s perfect cocktail: it’s the absolute best nourishment you can provide for your child. Full of nutrients, powerful probiotic bacteria, and tailored-made prebiotics, your breast milk is designed and optimized to support your baby’s unique growth and development for a lifetime of vibrant health.

1. Houghteling, P. D., & Walker, W. A. (2015). From Birth to “Immunohealth,” Allergies and Enterocolitis. Journal of Clinical Gastroenterology, 49, S7-S12.
2. Boix-Amorós, A., Collado, M. C., & Mira, A. (2016). Relationship between Milk Microbiota, Bacterial Load, Macronutrients, and Human Cells during Lactation. Frontiers in Microbiology, 7. doi:10.3389/fmicb.2016.00492
3. Chichlowski, M., Lartigue, G. D., German, J. B., Raybould, H. E., & Mills, D. A. (2012). Bifidobacteria Isolated From Infants and Cultured on Human Milk Oligosaccharides Affect Intestinal Epithelial Function. Journal of Pediatric Gastroenterology and Nutrition, 55(3), 321-327.
4. Ewaschuk, J. B., Diaz, H., Meddings, L., Diederichs, B., Dmytrash, A., Backer, J., . . . Madsen, K. L. (2008). Secreted bioactive factors from Bifidobacterium infantis enhance epithelial cell barrier function. AJP: Gastrointestinal and Liver Physiology, 295(5).
5. Ward, R. E., Niñonuevo, M., Mills, D. A., Lebrilla, C. B., & German, J. B. (2007). In vitro fermentability of human milk oligosaccharides by several strains of bifidobacteria. Molecular Nutrition & Food Research, 51(11), 1398-1405.
6. Rossi, M., Amaretti, A., & Raimondi, S. (2011). Folate Production by Probiotic Bacteria. Nutrients, 3(12), 118-134.


Emily Courtney is a Writer and Editor at Hyperbiotics and mom to two fun and active boys. Emily is passionate about natural wellness and helping others learn about the power of probiotics for vibrant health! For more ideas on how you can benefit from the power of probiotics and live healthier days, be sure to subscribe to our newsletter.

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