Early-Life Gut Bacteria Linked to Lower Risk of Allergies and Asthma in Children

Allergies and asthma are becoming more common in children globally, but a new international study led by researchers from the Technical University of Denmark (DTU) found a previously unknown mechanism that may reduce the risk of developing these conditions later in life. The study authors, who published their findings in Nature Microbiology, noted that infants colonized with certain bifidobacteria produce a gut metabolite that suppresses immune reactions to allergens, lowering the likelihood of allergies and asthma.^1,2

Bifidobacteria are healthy bacteria that are found in the intestines that help digest fiber, prevent infections, and produce compounds like B vitamins and healthy fatty acids. Low counts of bifidobacteria have been connected to many diseases, and bifidobacteria supplements have previously shown benefits in treating certain disease symptoms. Despite their importance, bifidobacteria make up less than 10% of the bacteria in the adult gut microbiome.³

"The key breakthrough is that we have now identified a specific mechanism that can suppress the development of allergic reactions in the immune system already during infancy,” Susanne Brix Pedersen, project leader and professor at DTU Bioengineering, said in a news release.²

Can Allergies and Asthma Be Prevented in Children?

Early-life exposure to microbes plays a key role in shaping immune development and the risk of allergies. The study authors noted that sensitization to food allergens, shown by the presence of food-specific immunoglobulin E (IgE), is an early sign of impaired immune tolerance. The body produces IgE antibodies that activate immune cells and trigger allergic reactions when the body encounters an allergen. These antibodies bind to allergens (eg, pollen or food proteins), causing symptoms such as itching, eczema, hay fever, and sometimes asthma, with higher IgE levels indicating a greater risk of allergy.^1,2

In the study, which included data from 3 birth cohorts based in Sweden, Germany, and Australia, researchers assessed 147 children from birth to age 5 and found that infants with high levels of certain bifidobacteria in their gut benefit from metabolites produced by these bacteria. Specifically, 1 metabolite, 4-hydroxyphenyl lactate (4-OH-PLA), helps suppress the immune system’s tendency to overreact to allergens.^1,2

“If we can translate this knowledge into a preventive strategy—for example, through probiotic supplements or enriched infant formula—it will be a major step forward in the fight against allergies and asthma, which currently affect millions of children worldwide," Brix Pedersen said.²

Researchers analyzed infant stool samples to identify gut bacteria and metabolite levels and used blood samples to measure IgE antibodies to food and airborne allergens. Experiments with human immune cells showed that the metabolite 4-OH-PLA directly inhibits IgE production, demonstrating a clear biological link between certain bifidobacteria, their metabolites, and healthy immune development in young children.^1,2

"It is remarkable that children born vaginally were 14 times more likely to acquire the bifidobacteria from their mothers. In addition, exclusive breastfeeding and contact with other young children during early life also contributed to increased abundance of these bifidobacteria in the gut. This means that natural mechanisms help to prevent the development of these diseases. However, our lifestyle has contributed to these bifidobacteria becoming much rarer, and it is therefore also important to look at other preventive measures that can help infants who are not colonized with them," Rasmus Kaae Dehli, a specialist in systems immunology at DTU Bioengineering, said in the news release.²

The findings suggest that adding 4-OH-PLA or probiotic bacteria that produce it could become a new strategy to help prevent allergies and asthma. The study authors noted that they see potential in dietary supplements or infant formula enhanced with these bifidobacteria or their metabolites to allow targeted prevention during the early months of life when the immune system is developing.^1,2

Understanding Allergies and Asthma in Children

Allergies and asthma are two of the most common chronic conditions among children, which present similar symptoms involving a child’s airway. According to the American Academy of Allergy, Asthma & Immunology, both conditions tend to run in families, making children who have one or both parents with an allergic disease more likely to develop allergies and/or asthma.^4,5

Allergies can trigger asthma attacks, particularly in children with allergic asthma, which is caused by exposure to allergens and often worsens during allergy seasons, though triggers can occur year-round. Most children with asthma have allergy-related triggers, while nonallergic asthma is triggered by factors such as infection, exercise, or stress, with infections being the most common triggers in children.^4,5

REFERENCES

1. Myers, P.N., Dehli, R.K., Mie, A. et al. Early-life colonization by aromatic-lactate-producing bifidobacteria lowers the risk of allergic sensitization. Nat Microbiol (2026). https://doi.org/10.1038/s41564-025-02244-9

2. Infant gut bacteria may be the key to preventing asthma and allergies. News release. EurerkAlert! January 14, 2026. Accessed January 23, 2026. https://www.eurekalert.org/news-releases/1112628

3. Why Bifidobacteria Are So Good for You. News release. Healthline. Updated July 13, 2023. Accessed January 23, 2026. https://www.healthline.com/nutrition/why-bifidobacteria-are-good

4. Prevention of Allergies and Asthma in Children. News release. American Academy of Allergy Asthma & Immunology. January 10, 2024. Accessed January 23, 2026. https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/prevention-of-allergies-and-asthma-in-children

5. HealthPartners staff. Asthma vs. allergies in children: How they’re different and how they’re connected. HealthPartners. Accessed January 23, 2026. https://www.healthpartners.com/blog/does-your-child-have-asthma-or-allergies/