Missing beneficial bacteria in infant guts linked to rising asthma and allergy cases

Nearly one in four infants lacks enough healthy gut bacteria essential for training their immune systems, putting them at greater risk of developing non-communicable diseases (NCDs) such as allergies, asthma, and eczema by age 2.

Bifidobacteria are among the first group of good bacteria to colonize the human gut, and their presence has been linked to positive health outcomes for the host, including protection against metabolic diseases, gastrointestinal tract infections, and inflammation.

A recent study published in Communications Biology analyzed the gut microbiomes of 412 infants, selected to represent the diverse demographics of the U.S, and found a widespread deficit of Bifidobacteria in infants. Long-term health data from the infants suggested that a lack of detectable Bifidobacteria in infants may contribute to the development of atopy, a genetic predisposition to developing allergic diseases.

Global estimates suggest that up to 40% of the population has some form of allergy to substances present in the environment—pollen, dust, mites, or animal dander. The last few decades have also witnessed a growing prevalence of allergic conditions among children, ranging from seasonal allergies with mild symptoms, such as a runny nose, sneezing, and itchy eyes, to severe eczema and life-threatening food allergies that can send someone into an anaphylactic shock.

Emerging data suggests that the rise in such NCDs actually begins during the first 1,000 days of a child’s life—inside the mother’s womb and through the first two years of life. Scientists believe that while environmental and lifestyle changes play a role, a key factor may be disruptions in the gut microbiome. In infants, this disruption includes the widespread loss of certain beneficial strains of Bifidobacterium that are essential for early immune development and long-term health.

A baby’s mode of delivery (C-section or vaginal birth), whether they were breastfed or formula-fed, and exposure to antibiotics can shape the diversity of their gut microbiome, a factor that has been linked to health issues later in life, including allergies, autoimmune diseases, obesity. Previous studies in the U.S. looking at gut bacteria in babies were mostly small and didn’t include data representative of the diverse infant demographic.

To fill in the gap, the researchers designed the My Baby Biome study, a seven-year longitudinal investigation that involved nationally representative data of both the infant gut microbiome and the compounds produced by the metabolic activities of the microbes.

Data analysis revealed that 25% of U.S. infants between 1 and 3 months of age were deficient in Bifidobacterium, and the deficiency was more pronounced in C-section births (35%) than in vaginal births (19%). In C-section infants, the beneficial bacteria were often replaced by potentially pathogenic bacteria that are known to use up human milk oligosaccharides, components in breast milk that shape the infant gut microbiome.

They also found that microbiomes rich in Bifidobacterium had fewer antimicrobial-resistant and disease-causing genes, along with more beneficial metabolic profiles.

The researchers highlight that while the term dysbiosis or imbalance in the microbiome is still up for debate, the strong correlation between microbiome composition and infant health suggests that the absence of these key Bifidobacterium strains represents a true dysbiosis in early life.

© 2025 Science X Network

Nearly one in four infants lacks enough healthy gut bacteria essential for training their immune systems, putting them at greater risk of developing non-communicable diseases (NCDs) such as allergies, asthma, and eczema by age 2.

Bifidobacteria are among the first group of good bacteria to colonize the human gut, and their presence has been linked to positive health outcomes for the host, including protection against metabolic diseases, gastrointestinal tract infections, and inflammation.

A recent study published in Communications Biology analyzed the gut microbiomes of 412 infants, selected to represent the diverse demographics of the U.S, and found a widespread deficit of Bifidobacteria in infants. Long-term health data from the infants suggested that a lack of detectable Bifidobacteria in infants may contribute to the development of atopy, a genetic predisposition to developing allergic diseases.

Global estimates suggest that up to 40% of the population has some form of allergy to substances present in the environment—pollen, dust, mites, or animal dander. The last few decades have also witnessed a growing prevalence of allergic conditions among children, ranging from seasonal allergies with mild symptoms, such as a runny nose, sneezing, and itchy eyes, to severe eczema and life-threatening food allergies that can send someone into an anaphylactic shock.

Emerging data suggests that the rise in such NCDs actually begins during the first 1,000 days of a child’s life—inside the mother’s womb and through the first two years of life. Scientists believe that while environmental and lifestyle changes play a role, a key factor may be disruptions in the gut microbiome. In infants, this disruption includes the widespread loss of certain beneficial strains of Bifidobacterium that are essential for early immune development and long-term health.

A baby’s mode of delivery (C-section or vaginal birth), whether they were breastfed or formula-fed, and exposure to antibiotics can shape the diversity of their gut microbiome, a factor that has been linked to health issues later in life, including allergies, autoimmune diseases, obesity. Previous studies in the U.S. looking at gut bacteria in babies were mostly small and didn’t include data representative of the diverse infant demographic.

To fill in the gap, the researchers designed the My Baby Biome study, a seven-year longitudinal investigation that involved nationally representative data of both the infant gut microbiome and the compounds produced by the metabolic activities of the microbes.

Data analysis revealed that 25% of U.S. infants between 1 and 3 months of age were deficient in Bifidobacterium, and the deficiency was more pronounced in C-section births (35%) than in vaginal births (19%). In C-section infants, the beneficial bacteria were often replaced by potentially pathogenic bacteria that are known to use up human milk oligosaccharides, components in breast milk that shape the infant gut microbiome.

They also found that microbiomes rich in Bifidobacterium had fewer antimicrobial-resistant and disease-causing genes, along with more beneficial metabolic profiles.

The researchers highlight that while the term dysbiosis or imbalance in the microbiome is still up for debate, the strong correlation between microbiome composition and infant health suggests that the absence of these key Bifidobacterium strains represents a true dysbiosis in early life.

© 2025 Science X Network