Bifidobacterium infantis is one of the most important early-life bacteria for supporting toddler gut health and immune development. In this article, we explore new clinical research on the strain B. infantis YLGB-1496 and its impact on respiratory infections, diarrhea, and microbiome stability in young children.
Content Outline
Why the Infant Gut Microbiome Matters for Immunity
Within the gastrointestinal tract lives a diverse ecosystem of trillions of microbes, from archaea to bacteria. Collectively known as the gut microbiota, this community of microorganisms is integral to your immunity, metabolism, cognition, and digestion [1]. So, the healthier your gut is, the healthier you will be. The development of the gut microbiota starts in infancy, and this is one of its most critical development stages.
In children, the development of the digestive ecosystem is fundamental for shaping immune homeostasis and digestion, including nutrient absorption [2]. One of the key nutrients broken down by gut microbes is human milk oligosaccharides (HMOs), an abundant and important sugar found in human milk that acts as a source of nourishment for beneficial bacteria, such as Bifidobacteria.
By breaking down HMOs, Bifidobacteria strains transform them into health-promoting metabolites, such as short-chain fatty acids (SCFAs), which support gut health and immunity [3]. An imbalanced gut microbiota in children can increase the chance of gastrointestinal disorders, like irritable bowel syndrome (IBS), allergic conditions, and metabolic disorders, including obesity [4].
Bifidobacteria are one of the early colonizers of the human gut. Because they are among the most abundant microbes in the colon, they play important roles in maintaining the gut ecosystem. They have also been well studied in children and have been shown to reduce the risk and duration of antibiotic-associated diarrhea and infectious diarrhea [5]. It also has other protective benefits against respiratory illnesses, atopic eczema, and infant colic.
In this article, we focus on the results of a recent trial investigating the benefits of a specific Bifidobacterium strain, B. infantis YLGB-1496, following a 12-week supplementation in children. By understanding the impact of this probiotic strain on the pediatric gut, scientists can better understand how these beneficial microbes can impact gut health.
What is Bifidobacteria infantis YLGB-1496?
Bifidobacteria infantis YLGB-1496 is a well-studied probiotic strain of Bifidobacteria that has been isolated from human breast milk and can be used to promote health in children [6]. It has recently been the focus of a study by Mageswary and colleagues to better understand how probiotic supplementation in children contributes to gut health by modulating the microbiome.
12-Week Clinical Trial: Study Design Explained
The study was a double-blind, randomized, placebo-controlled study that was made up of 119 participants, split into 2 groups, probiotic or placebo group.
At weeks 0, 6, and 12, oral and fecal samples were collected to assess for respiratory and gastrointestinal illness incidence, inflammatory biomarkers, and gut microbiota composition.
What were the main findings of the study?
The main results of the study are shown in Table 1 below. It was shown that probiotic supplementation of the B. infantis strain significantly reduced the incidence of respiratory illness over 12 weeks compared to a placebo. B. infantis also reduced the incidence of diarrhea.
Table 1. The main results of the study show the incidence of respiratory and gastrointestinal illness between placebo and probiotic groups.
|
Week 0 |
Week 6 |
Week 12 |
||||
|
Probiotic group |
Placebo group |
Probiotic group |
Placebo group |
Probiotic group |
Placebo group |
|
|
Respiratory illness = Yes |
22 |
22 |
13 |
27 |
9 |
25 |
|
Respiratory illness = No |
38 |
37 |
47 |
32 |
34 |
51 |
|
Diarrhea in past month = Yes |
32 |
28 |
11 |
26 |
13 |
19 |
|
Diarrhea in past month = No |
28 |
31 |
49 |
33 |
47 |
40 |
The study also found that daily supplementation with B. infantis YLGB-1496 resulted in:
✅ Fewer antibiotic prescriptions
✅ Fewer clinic visits
✅ Favourable anti-inflammatory profile
✅Ecological stability in the gut microbiota
✅ Preservation of SCFA-producing bacteria, which declined in the placebo group
Keep reading as we break down the main respiratory, gastrointestinal, immunological, and microbiological results.
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Does B. infantis Reduce Respiratory Illness in Toddlers?
At the start of the trial, there were no significant differences between the probiotic and placebo groups in relation to respiratory outcomes. However, after 6 weeks, the probiotic group had fewer respiratory issues than the placebo group, with just 21.7% reporting an issue, compared to 45.8% in the placebo group. At 12 weeks, just 15% of the probiotic group had a respiratory illness compared to 42.4% of participants given a placebo.
Antibiotic use was also markedly lower in the probiotic group. More than double the number of people in the placebo group had taken antibiotics at 12 weeks compared to the probiotic group.
These results demonstrate that daily supplementation with B. infantis YLGB-1496 had a protective benefit against respiratory tract illness in children.
Can B. infantis Improve Diarrhea and Gut Health?
As well as reducing the incidence of diarrhea in participants, the probiotic also significantly improved bowel regularity (Table 2). Therefore, demonstrating that probiotic consumption can normalize bowel habits and improve overall gastrointestinal comfort.
Table 2. Rate of defecation per week, probiotic vs placebo group.
|
Week 0 |
Week 6 |
Week 12 |
||||
|
Probiotic group |
Placebo group |
Probiotic group |
Placebo group |
Probiotic group |
Placebo group |
|
|
Defecation rate per week |
7.58土0.63 |
7.71土0.69 |
12.76土0.84 |
7.6土0.62 |
11.61土0.85 |
7.9土0.75 |
Overall, these results suggest that B. infantis can reduce diarrhea and it’s associated symptoms, with 18.3% of the children given the probiotic getting diarrhea compared to 44.1% of the placebo group.
How Does B. infantis Affect Immune Biomarkers?
Common fecal biomarkers relating to gut inflammation and immunity were tested at week 0, 6, and 12. Although the levels were similar for both the probiotic and placebo groups, there were distinct baseline differences:
-
The probiotic group had lower fecal IgA at the start of the trial.
-
The probiotic group had higher feval calprotectin levels at week 0.
The changes in fecal biomarkers are shown in Figure 1.
Figure 1. Fecal biomarker concentrations in children given a probiotic or placebo supplement for 12 weeks. Figure 1A shows that fecal biomarkers are relatively similar between the 2 groups at the start of the trial, with lower fecal IgA levels and higher calprotectin in the probiotic group. At week 6 (Figure 1B), pro-inflammatory cytokines in the probiotic group are reduced, as is the inflammation marker calprotectin. Figure 1C shows that at week 12, the beneficial effects in the gut are maintained with a significant reduction in calprotectin being sustained, while an increase in IgA suggests that the mucosal immunity within the gut was harnessed over the trial period.
Oral biomarkers showed that, over 12 weeks, cortisol levels were reduced in the probiotic group. This suggests a clear link between the gut-brain axis and a potential beneficial, systemic effect on stress in the probiotic group (Figure 2).
Figure 2. Immune and stress biomarker concentrations from oral samples of children given a probiotic or placebo supplement for 12 weeks. No significant differences were observed between the 2 groups over the trial period, but cortisol levels fell significantly in the probiotic group compared with the placebo group.
Does This Probiotic Change the Gut Microbiome?
The trial found that the supplementation of a probiotic strain did not result in a broad compositional restructuring of the gut microbiome, but instead stabilized the gut ecosystem against common shifts. Some of the observations recorded included:
-
Alpha diversity: Microbial richness increased at week 6 in the placebo group but returned to baseline by week 12. The probiotic group maintained diversity across the trial period, suggesting that it supported microbial resilience.
-
Beta diversity: No major changes in beta diversity, similar to the previous finding that probiotic supplementation does not produce significant changes, especially in adults who have a stable and resilient microbiota [7].
-
Compositional differences: The placebo group showed significant reductions in important health-promoting microbes, including prominent butyrate producers and mucin degraders. In the probiotic group, the relative abundance of some butyrate-producers decreased, suggesting that B. infantis worked to rebalance the microbial ecosystem, and supported the increase in mucin-degrading species.
What This Means for Probiotic Use in Young Children
Overall, these results demonstrate that childhood supplementation of a probiotic bacterial strain, B. infantis YLGB-1496 has many significant health benefits for children aged 1 to 3 years. The strain helps balance the gut microbial community, reducing the incidence of respiratory and gastrointestinal illnesses, which in turn results in fewer clinic visits and reduced antibiotic use.
These results also coincided with reduced pro-inflammatory biomarkers and salivary cortisol, suggesting a gut-brain axis benefit. While the placebo group had a gut microbiome composition closely related to dysbiosis, or an imbalance in the microbiota, the probiotic group maintained stability. The results of this study highlight that probiotic supplementation with B. infantis YLGB-1496 is a safe and effective intervention in children that can support gut health and immunity and reduce the burden of common childhood ailments.
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Summary
The results of this study provide valuable insights into the benefits of a specific probiotic strain, B. infantis YLGB-1496, for children's health. From lower rates of common illnesses to enhancing the resilience of the colonic ecosystem, the study demonstrates that probiotic supplementation could be an important intervention in promoting children’s health.
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Frequently Asked Questions About Bifidobacterium infantis in Toddlers
1. Is Bifidobacterium infantis safe for toddlers?
Yes. Bifidobacterium infantis is considered safe for healthy toddlers when used in age-appropriate doses. It is a naturally occurring bacterium found in breastfed infants and is one of the earliest colonisers of the infant gut. As with any supplement, parents should consult a healthcare professional before starting a probiotic.
2. What does Bifidobacterium infantis do for a child’s immune system?
Bifidobacterium infantis supports immune health through several mechanisms. In clinical research, supplementation with B. infantis YLGB-1496 was associated with reduced respiratory infections, lower inflammatory markers such as calprotectin, and increased fecal IgA.
3. Can B. infantis help prevent respiratory infections in toddlers?
Yes. In a 12-week randomized controlled trial, toddlers who received B. infantis YLGB-1496 experienced significantly fewer respiratory illnesses compared to those given a placebo.
4. Does Bifidobacterium infantis help with diarrhea?
Yes, strain-specific evidence suggests that B. infantis may reduce the incidence of diarrhea in young children. In the current clinical trial, children receiving B. infantis supplementation had lower rates of diarrhea and improved bowel regularity compared to the placebo group.
5. How long does it take for probiotics to work in toddlers?
Some benefits, such as improvements in bowel habits, may be observed within a few weeks. In the 12-week study of B. infantis YLGB-1496, reductions in respiratory symptoms and inflammatory markers were evident by week 6 and sustained through week 12. However, individual responses vary depending on the child’s existing gut microbiome, diet, and health status.
6. Does B. infantis change the gut microbiome composition?
Rather than dramatically reshaping the gut microbiome, B. infantis appears to promote ecological stability. In the clinical trial, children taking the probiotic maintained microbial diversity and preserved beneficial SCFA-producing bacteria, while the placebo group showed declines in some health-promoting microbes. This suggests that B. infantis may help protect against microbiome imbalances, especially during early childhood.
7. What makes Bifidobacterium infantis different from other probiotics?
Not all probiotics are the same. Benefits are strain-specific, meaning results seen with B. infantis YLGB-1496 cannot automatically be applied to other probiotic strains. B. infantis is uniquely adapted to digest human milk oligosaccharides (HMOs), allowing it to thrive in the infant gut and produce immune-supporting metabolites.
Original article source: Mageswary et al., (2026). Clinical benefits of Bifidobacterium infantis YLGB-1496 in modulating gut microbiota and immunity in young children.
Author details
Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome. She has written extensively on inflammatory bowel disease, prebiotics, and microbiome research.
Her work focuses on translating complex medical science into evidence-based, practical health guidance.
Last updated: February 2026
