Probiotics for Breastfeeding: Evidence-Based Strains for Nursing Moms and Their Babies
What the clinical research says about probiotics while breastfeeding—and which strains matter most
Breastfeeding is one of the most consequential periods for shaping a baby's lifelong gut health. The bacteria that colonize an infant's digestive tract in those earliest months lay the foundation for immune development, nutrient absorption, and protection against chronic disease. What many nursing mothers don't realize is that their own gut microbiome plays a direct role in this process—and probiotics can meaningfully support both sides of the equation.
Research has uncovered a fascinating biological mechanism called the entero-mammary pathway, through which select bacteria from a mother's gut are transported to her mammary glands by immune cells and ultimately delivered to her infant through breast milk.[1] This discovery has significant implications: by optimizing her own gut microbiome, a breastfeeding mother may directly influence the microbial environment her baby inherits.
This maternal microbiome support ideally begins well before birth — the same Lactobacillus strains that benefit nursing mothers also play a role in creating the vaginal and endometrial environment associated with successful conception and implantation, a connection explored in our article on probiotics for fertility.
But not all probiotics are created equal—and for nursing moms, choosing the right strains backed by clinical evidence is essential. This guide examines the peer-reviewed research behind specific probiotic strains that support maternal health during lactation and infant gut development during breastfeeding.
Key Takeaways
- Probiotics are safe during breastfeeding. A systematic review and meta-analysis of randomized controlled trials concluded that probiotic and prebiotic products are safe for use during pregnancy and lactation, with no serious adverse effects reported for mother or infant.[2]
- Lactobacillus fermentum reduced mastitis incidence by 51% in a randomized controlled trial of breastfeeding women, while also lowering Staphylococcus counts in breast milk.[3]
- Lactobacillus reuteri significantly reduces infant colic in breastfed babies, with a meta-analysis recommending it as an effective intervention for breastfed infants with colic.[4]
- Bifidobacterium infantis persistently colonizes the infant gut for up to one year when supplemented early in life, uniquely equipped to metabolize human milk oligosaccharides (HMOs).[5]
- Maternal probiotic supplementation increases beneficial bacteria in breast milk by 24% and reduces pathogenic bacteria, according to a meta-analysis of 24 randomized controlled trials.[6]
- Multi-strain formulations without synthetic fillers ensure the probiotic bacteria you're introducing aren't undermined by additives that can disrupt gut health.
Why Probiotics Matter During Breastfeeding
The postpartum period represents a critical window for both maternal recovery and infant microbiome development. A mother's gut health during this time influences far more than her own digestion—it shapes the microbial inheritance she passes to her baby.
The Entero-Mammary Pathway: Your Gut Talks to Your Breast Milk
For decades, breast milk was considered sterile. We now know it harbors a diverse microbial community, and emerging evidence points to a remarkable mechanism behind this: the entero-mammary pathway. Research published in Advances in Nutrition describes how specific bacteria from the maternal gastrointestinal tract are captured by dendritic cells, transported through the lymphatic system, and delivered to the mammary glands during late pregnancy and lactation.[1]

A 2024 observational study confirmed this pathway directly, finding that approximately 23% of breast milk microbiota originated from the maternal gut and roughly 26% of the infant gut microbiota derived from breast milk. Genera including Bifidobacterium and Lactobacillus were common across all three sites—maternal gut, breast milk, and infant gut.[7]
The practical implication is powerful: a mother who supports her own gut ecosystem with targeted probiotic strains may be indirectly nourishing her infant's developing microbiome through every feeding. For women experiencing signs of Lactobacillus deficiency, restoring these beneficial populations becomes doubly important during lactation.
Why Breastfed Babies Need Bifidobacterium
Historically, the gut of a breastfed infant was dominated by Bifidobacterium species until weaning. However, research has documented a generational decline in these protective bacteria among infants in industrialized nations—likely driven by widespread antibiotic use, cesarean deliveries, and formula feeding.[5] This decline has been linked to elevated rates of allergic and autoimmune conditions in resource-rich countries, underscoring the importance of actively supporting Bifidobacterium colonization during the breastfeeding window.
The Human Milk Oligosaccharide Connection
Breast milk contains human milk oligosaccharides (HMOs)—complex sugars that babies cannot digest themselves. These HMOs exist specifically to feed beneficial Bifidobacterium species, particularly B. infantis, which possesses unique genetic machinery to metabolize them. When B. infantis ferments HMOs, it produces lactate and acetate that lower intestinal pH, creating an environment inhospitable to pathogens.[8] This elegant system means breast milk and Bifidobacterium evolved together—each optimizing the other's effectiveness.
Best Probiotic Strains for Nursing Moms and Breastfed Babies
Not every probiotic strain has equal relevance during breastfeeding. The strains that matter most are those with clinical evidence demonstrating benefits for maternal breast health, infant digestive comfort, immune development, or microbiome composition. Here's what the research shows about specific strains found in MicroBiome Restore.
Lactobacillus fermentum: Mastitis Prevention
Mastitis—painful breast tissue inflammation, often driven by bacterial infection—affects up to one in five breastfeeding women and is a leading cause of premature weaning.[3] Lactobacillus fermentum was originally isolated from the breast milk of healthy women, and its clinical track record during lactation is compelling.
A multicenter randomized, double-blind, placebo-controlled trial followed 291 breastfeeding women over 16 weeks. Women receiving L. fermentum CECT5716 daily experienced a 51% reduction in the incidence rate of clinical mastitis compared to the control group. Critically, Staphylococcus counts—the primary pathogen behind lactational mastitis—were significantly lower in the breast milk of the probiotic group at the end of the intervention period.[3]
A systematic review and meta-analysis of six randomized controlled trials confirmed these findings broadly, concluding that oral probiotic supplementation during the perinatal period reduced mastitis incidence, with L. fermentum and L. salivarius both demonstrating significant reductions in bacterial load in breast milk.[9]
Lactobacillus reuteri: Infant Colic Relief
Few challenges test new parents like infant colic—prolonged, inconsolable crying that can strain the entire family. Lactobacillus reuteri DSM 17938 has become one of the most studied probiotic interventions for this condition, particularly in breastfed infants.
An individual participant data meta-analysis published in Pediatrics, pooling data from four double-blind randomized controlled trials involving 345 infants, found that infants receiving L. reuteri were nearly twice as likely as those receiving placebo to experience treatment success. In breastfed infants specifically, the intervention effects were dramatic, with a number needed to treat (NNT) of just 2.6—meaning fewer than three breastfed babies needed treatment for one additional infant to experience at least 50% reduction in crying time.[4]
Bifidobacterium infantis: Infant Gut Colonization
Bifidobacterium longum subsp. infantis is uniquely adapted to thrive in the breastfed infant gut. Unlike other Bifidobacterium species, B. infantis possesses the complete genetic machinery to bind, transport, and ferment the full spectrum of HMOs in breast milk.[8]
A follow-up to a randomized controlled trial published in Pediatric Research demonstrated that exclusively breastfed infants supplemented with B. infantis EVC001 maintained significantly elevated levels of fecal B. infantis—2.5 to 3.5 log units higher than unsupplemented infants—at 6 through 12 months of age.[5] This persistent colonization is particularly noteworthy because most probiotic interventions produce only transient effects.
For mothers concerned about their infant's Bifidobacterium levels, this research underscores the synergy between breastfeeding and Bifidobacterium supplementation—breast milk provides the HMOs that selectively fuel B. infantis growth.
Lactobacillus rhamnosus and Lactobacillus acidophilus: Immune and Digestive Support
Lactobacillus rhamnosus is among the most extensively researched probiotic strains worldwide. The ProPACT trial found that maternal supplementation with L. rhamnosus GG during pregnancy and postpartum was associated with a 40% reduction in atopic dermatitis (eczema) risk in infants by age two when both mother and infant received supplementation.[10]
Lactobacillus acidophilus is naturally found in breast milk and is a foundational species for both maternal vaginal and digestive health during the postpartum period. Clinical research has confirmed its role in supporting healthy bacterial balance across mucosal surfaces—important for mothers recovering from delivery. Read more about the clinical evidence behind Lactobacillus acidophilus benefits.
Additional Strains With Lactation-Relevant Benefits
Lactobacillus salivarius has been studied alongside L. fermentum for mastitis prevention, with one trial demonstrating a 56% decrease in mastitis incidence when administered during the last weeks of pregnancy.[9] Bifidobacterium lactis supports immune modulation and has been included in multiple perinatal probiotic trials. And Lactobacillus plantarum, known for its robust intestinal barrier support, may benefit nursing mothers dealing with postpartum digestive irregularities. You can explore the research on L. plantarum health benefits in more detail.

| Strain | Primary Benefit During Breastfeeding | Key Evidence |
|---|---|---|
| L. fermentum | Mastitis prevention, breast health | 51% reduction in mastitis incidence (RCT)[3] |
| L. reuteri | Infant colic relief | NNT of 2.6 in breastfed infants (meta-analysis)[4] |
| B. infantis | Infant gut colonization | Persistent colonization for 12+ months (RCT follow-up)[5] |
| L. rhamnosus | Immune support, eczema prevention | 40% reduced eczema risk (ProPACT trial)[10] |
| L. salivarius | Mastitis prevention | 56% decrease in mastitis incidence (RCT)[9] |
| L. acidophilus | Vaginal and digestive health | Naturally found in breast milk; mucosal balance[11] |
| B. longum, B. bifidum, B. lactis | Infant immune development | Increased beneficial bacteria in infant gut (meta-analysis)[6] |
26 Clinically Studied Strains in One Filler-Free Formula
MicroBiome Restore contains every strain discussed above—plus 19 additional evidence-backed strains—in a single daily serving. No titanium dioxide. No microcrystalline cellulose. No magnesium stearate. Just 15 billion CFU of comprehensive probiotic support.
How Probiotics Enhance Breast Milk Composition

The effect of maternal probiotic supplementation extends beyond the mother's own gut—it can measurably alter the composition and protective quality of her breast milk.
A landmark 2023 systematic review and meta-analysis published in the American Journal of Obstetrics & Gynecology MFM, encompassing 24 randomized controlled trials with 2,761 mothers and 1,756 infants, quantified these effects comprehensively. Maternal probiotic supplementation increased the detection rate of beneficial bacteria in breast milk by 24%, elevated the mean abundance of beneficial bacteria, and simultaneously reduced pathogenic bacteria concentrations. The review concluded that Lactobacillus, Bifidobacterium, and Streptococcus thermophilus can be safely used as maternal supplements to promote infant health.[6]
Reducing Pathogenic Staphylococcus
Elevated Staphylococcus counts in breast milk are associated with both symptomatic mastitis and subclinical breast discomfort. Multiple trials have demonstrated that oral Lactobacillus supplementation during lactation can significantly reduce Staphylococcus load. In one trial, L. fermentum supplementation for three weeks reduced Staphylococcus levels in breast milk with statistical significance.[3] This bacterial rebalancing doesn't just prevent mastitis—it improves the overall microbial quality of the milk the infant receives.
Lowering Inflammatory Markers
A 2024 observational study published in Frontiers in Nutrition found that maternal probiotic use was associated with lower levels of C-reactive protein (CRP) and interleukin-6 (IL-6)—two key inflammatory markers—in breast milk. Infants of probiotic-supplemented mothers also showed higher abundances of Bifidobacteria and Lactobacillus in their gut microbiomes at both one and six months of age.[12]
Supporting the Complete Ecosystem
Breast milk quality depends not just on probiotic strains but on the prebiotics that fuel them. MicroBiome Restore includes 9 organic prebiotics—including Jerusalem artichoke (a rich source of inulin), acacia fiber, maitake mushroom, and fig fruit—that nourish beneficial bacteria and support their colonization in your gut. When your gut flora thrives, the downstream effects on breast milk composition follow.
Safety of Probiotics While Breastfeeding
Safety is understandably the foremost concern for nursing mothers considering any supplement. The reassuring answer from the clinical literature: probiotics are well-established as safe during lactation.
A systematic review and meta-analysis published in Nutrients evaluated the adverse effects of probiotic, prebiotic, and synbiotic supplementation during pregnancy and lactation across 100 eligible studies. The researchers found that adverse effects associated with probiotic and prebiotic use did not pose any serious health concerns to mother or infant. Only one study reported mild effects—increased vaginal discharge and changes in stool consistency—when administering L. rhamnosus and L. reuteri.[2]
A review published in Canadian Family Physician further confirmed that systemic absorption of probiotics is rare in healthy individuals, and that probiotics are unlikely to be transferred into breast milk in clinically significant concentrations—meaning the risk of direct probiotic bacteremia in infants through breastfeeding is essentially negligible.[13]
When to Consult Your Healthcare Provider
While probiotics are broadly safe during breastfeeding, women with compromised immune systems, serious underlying health conditions, or infants in neonatal intensive care should consult their healthcare provider before beginning supplementation. This is standard guidance for any supplement during the postpartum period. Probiotic supplementation should complement—not replace—medical care for conditions like mastitis that may require antibiotic treatment.
What to Look for in a Probiotic While Breastfeeding
Choosing a probiotic during lactation requires attention to factors that matter year-round—but take on added significance when you're nourishing two bodies simultaneously.
Multi-Strain Diversity
The maternal and infant gut ecosystems depend on diverse bacterial communities, not a single species. A multi-strain probiotic that includes both Lactobacillus and Bifidobacterium species—the two genera most relevant to breastfeeding outcomes—provides broader coverage than single-strain formulas. The meta-analysis by Alemu et al. specifically identified Lactobacillus, Bifidobacterium, and Streptococcus thermophilus as maternal supplements that promote infant health.[6]
Clean Formulation: Why Fillers Matter More Than You Think
Many commercial probiotics contain inactive ingredients that can undermine the very gut health they claim to support. Microcrystalline cellulose (MCC), magnesium stearate, and titanium dioxide are standard industry additives with emerging safety concerns. For a breastfeeding mother, these concerns are amplified—anything that disrupts maternal gut health can ripple through to the infant via the entero-mammary pathway.
Learning to identify hidden fillers on supplement labels is a skill every nursing mother should develop. Look for products that use clean capsule materials—pullulan capsules, for example, are fermented and prebiotic, providing a delayed-release mechanism without synthetic coatings.
Adequate CFU Count
Colony-forming units (CFU) reflect the number of viable bacterial organisms in a probiotic supplement. Clinical trials demonstrating lactation-specific benefits typically used doses ranging from 1 billion to 10 billion CFU of individual strains. A comprehensive multi-strain formula delivering 15 billion CFU per serving provides meaningful therapeutic levels across multiple bacterial species.
Prebiotic Support
Prebiotics—non-digestible fibers that selectively feed beneficial bacteria—are the overlooked half of the gut health equation. Inulin from Jerusalem artichoke has been specifically studied for its benefits during the perinatal period, showing favorable effects on maternal gut health.[14] Acacia fiber supports the growth of Bifidobacterium and Lactobacillus populations, and research on its prebiotic properties for sensitive digestive systems makes it especially relevant for the postpartum period, when many women experience gastrointestinal sensitivity.

Checklist: Choosing a Probiotic for Breastfeeding
Look for: Multi-strain formula with both Lactobacillus and Bifidobacterium species; adequate CFU count (10–15 billion+); included prebiotics; filler-free formulation; delayed-release capsule technology.
Avoid: Single-strain products with limited clinical relevance; formulas containing microcrystalline cellulose, titanium dioxide, or synthetic flow agents; proprietary blends that hide individual strain amounts; products without third-party testing.
The Role of Prebiotics for Nursing Mothers
Probiotics get most of the attention, but prebiotics are equally critical during breastfeeding—for a reason that goes beyond maternal gut health. Breast milk itself is essentially a prebiotic delivery system. HMOs, the third most abundant component of breast milk after lactose and lipids, are prebiotics designed by nature to feed infant gut bacteria.

Supporting the maternal gut with dietary and supplemental prebiotics helps maintain the diverse bacterial populations that are transferred through the entero-mammary pathway. Specific prebiotic fibers relevant to the breastfeeding period include inulin (naturally concentrated in Jerusalem artichoke), acacia fiber (from Acacia senegal), and beta-glucans from maitake mushroom, which support both gut health and immune function—a dual benefit for recovering postpartum bodies.
Research on inulin during the perinatal period has demonstrated favorable effects on maternal gut microbiota composition, suggesting that prebiotic supplementation may enhance the diversity of bacteria available for transfer to breast milk.
Frequently Asked Questions
Do probiotics cause gas in breastfed babies?
This is one of the most common concerns among nursing mothers, and the clinical evidence is reassuring. A meta-analysis of L. reuteri trials in breastfed infants found no significant increase in adverse gastrointestinal events compared to placebo.[4] Some mothers may notice mild changes in their baby's stool during the first few days of starting a probiotic—this is typically transient and reflects the gut microbiome adjusting. In fact, probiotics are specifically studied as a treatment for infant gas and colic, not as a cause.
Can probiotics pass through breast milk to my baby?
Research on the entero-mammary pathway suggests that select bacteria from the maternal gut can reach the mammary gland through immune cell-mediated transport.[1] While not all orally consumed probiotic strains appear in breast milk at detectable levels, maternal supplementation has been consistently associated with changes in infant gut microbiome composition—including higher abundances of Bifidobacteria and Lactobacillus—suggesting meaningful transfer through one or more mechanisms.[12]
When should I start taking probiotics while breastfeeding?
Research suggests that beginning probiotic supplementation during late pregnancy (third trimester) and continuing through lactation provides the broadest window of benefit. Trials demonstrating mastitis prevention initiated supplementation within the first days postpartum, while eczema prevention trials began during the third trimester.[3][10] That said, starting at any point during breastfeeding can still be beneficial for maternal gut health and, potentially, breast milk composition.
What supplements should I avoid while breastfeeding?
While probiotics are considered safe, nursing mothers should be cautious about supplements containing unnecessary fillers and flow agents that haven't been evaluated for lactation safety. Specific herbs, high-dose vitamins, and certain botanical extracts may also warrant caution. Always review the full ingredient panel—including inactive ingredients—and consult your healthcare provider about any supplement during lactation.
Is a probiotic with 15 billion CFU enough for breastfeeding?
Yes. Clinical trials demonstrating meaningful lactation-related outcomes have used individual strain doses ranging from 100 million to 10 billion CFU. A multi-strain formula delivering 15 billion CFU total provides therapeutic levels across multiple species—covering maternal digestive health, breast health, and strains relevant to infant gut development. Higher CFU counts are not necessarily more effective; strain diversity and formulation quality matter as much as total count.
Supporting Your Breastfeeding Journey With Science-Backed Probiotics
The science connecting maternal gut health to infant development through breastfeeding has never been clearer. From the entero-mammary pathway that transports beneficial bacteria to breast milk, to the specific probiotic strains clinically demonstrated to prevent mastitis, reduce infant colic, and support lasting gut colonization—the evidence offers nursing mothers a concrete, research-backed strategy for supporting both their own health and their baby's microbiome during this critical period.
What matters most is choosing a probiotic that reflects this evidence: multi-strain diversity spanning both Lactobacillus and Bifidobacterium genera, complementary prebiotic support, and a formulation free of the fillers and flow agents that can undermine gut health. Explore our complete guide to MicroBiome Restore to understand how our 26-strain, filler-free formulation was built around these principles.
Your breast milk is already one of the most remarkable substances in nature. The right probiotic helps ensure your gut is giving it every possible advantage.
Built for the Breastfeeding Period—and Beyond
MicroBiome Restore delivers 26 clinically studied probiotic strains, 9 organic prebiotics, and 80+ trace minerals in a filler-free pullulan capsule. Every ingredient earns its place by supporting your microbiome—never by making our manufacturing easier.
References
- Rodríguez, J. M. (2014). The origin of human milk bacteria: is there a bacterial entero-mammary pathway during late pregnancy and lactation? Advances in Nutrition, 5(6), 779–784. https://doi.org/10.3945/an.114.007229
- Sheyholislami, H., & Connor, K. L. (2021). Are probiotics and prebiotics safe for use during pregnancy and lactation? A systematic review and meta-analysis. Nutrients, 13(7), 2382. https://doi.org/10.3390/nu13072382
- Hurtado, J. A., Maldonado-Lobón, J. A., Díaz-Ropero, M. P., Flores-Rojas, K., Muñoz-Quezada, S., Lara-Villoslada, F., ... & Olivares, M. (2017). Oral administration to nursing women of Lactobacillus fermentum CECT5716 prevents lactational mastitis development: A randomized controlled trial. Breastfeeding Medicine, 12(4), 202–209. https://doi.org/10.1089/bfm.2016.0173
- Sung, V., D'Amico, F., Cabana, M. D., Chau, K., Koren, G., Savino, F., ... & Indrio, F. (2018). Lactobacillus reuteri to treat infant colic: A meta-analysis. Pediatrics, 141(1), e20171811. https://doi.org/10.1542/peds.2017-1811
- O'Brien, C. E., Meier, A. K., Cernioglo, K., Mitchell, R. D., Casaburi, G., Frese, S. A., Henrick, B. M., Underwood, M. A., & Smilowitz, J. T. (2022). Early probiotic supplementation with B. infantis in breastfed infants leads to persistent colonization at 1 year. Pediatric Research, 91(3), 627–636. https://doi.org/10.1038/s41390-020-01350-0
- Alemu, B. K., Azeze, G. G., Wu, L., Lau, S., Wang, C., & Wang, Y. (2023). Effects of maternal probiotic supplementation on breast milk microbiome and infant gut microbiome and health: A systematic review and meta-analysis of randomized controlled trials. American Journal of Obstetrics & Gynecology MFM, 5(11), 101148. https://doi.org/10.1016/j.ajogmf.2023.101148
- Meng, L., Xie, H., et al. (2024). Gut-mammary pathway: Breast milk microbiota as a mediator of maternal gut microbiota transfer to the infant gut. Journal of Functional Foods, 123, 106236. https://doi.org/10.1016/j.jff.2024.106236
- Chichlowski, M., Shah, N., Wampler, J. L., Wu, S. S., & Vanderhoof, J. A. (2020). Bifidobacterium longum subspecies infantis (B. infantis) in pediatric nutrition: Current state of knowledge. Nutrients, 12(6), 1581. https://doi.org/10.3390/nu12061581
- Yu, Q., Xu, C., Wang, M., Zhu, J., Yu, L., Yang, Z., ... & Fang, S. (2022). The preventive and therapeutic effects of probiotics on mastitis: A systematic review and meta-analysis. PLoS ONE, 17(9), e0274467. https://doi.org/10.1371/journal.pone.0274467
- Wickens, K., Barthow, C., Mitchell, E. A., Kang, J., van Zyl, N., Abels, P., ... & Crane, J. (2018). Effects of Lactobacillus rhamnosus HN001 in early life on the cumulative prevalence of allergic disease to 11 years. Pediatric Allergy and Immunology, 29(8), 808–814. https://doi.org/10.1111/pai.12977
- Martín, R., Olivares, M., Marín, M. L., Fernández, L., Xaus, J., & Rodríguez, J. M. (2005). Probiotic potential of 3 Lactobacilli strains isolated from breast milk. Journal of Human Lactation, 21(1), 8–17. https://doi.org/10.1177/0890334404272393
- Hasavira, A. H., Muthukumaraswamy, S. D., Slykerman, R. F., & D'Souza, M. (2024). Maternal oral probiotic use is associated with decreased breastmilk inflammatory markers, infant fecal microbiome variation, and altered recognition memory responses in infants—a pilot observational study. Frontiers in Nutrition, 11, 1456111. https://doi.org/10.3389/fnut.2024.1456111
- Elias, J., Bozzo, P., & Einarson, A. (2011). Are probiotics safe for use during pregnancy and lactation? Canadian Family Physician, 57(3), 299–301. https://pmc.ncbi.nlm.nih.gov/articles/PMC3056676/
- Zaidi, A. Z., Moore, S. E., & Okala, S. G. (2021). Impact of maternal nutritional supplementation during pregnancy and lactation on the infant gut or breastmilk microbiota: A systematic review. Nutrients, 13(4), 1137. https://doi.org/10.3390/nu13041137


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