Susanne Brix Pedersen, professor at DTU Bioengineering

Susanne Brix Pedersen

 Inside the Study Linking Infant Gut Bacteria to Lower Allergy Risk

Infants colonized early with specific bifidobacteria that produce aromatic lactate metabolites were significantly less likely to develop 

 and atopic dermatitis in childhood, according to new longitudinal data published in 

The findings add mechanistic clarity to the long-standing hypothesis that the infant gut microbiome helps shape immune tolerance during a narrow developmental window. In a prospective cohort of 147 children followed from birth to age 5, investigators identified a distinct microbiota–metabolite–immune axis associated with reduced food allergen–specific immunoglobulin E (IgE) and lower rates of eczema

The study, led by investigators at the Technical University of Denmark (DTU), tracked infants born between 2003 and 2005 in Sweden, with serial fecal sampling at 8 time points from birth through 5 years of age, alongside maternal samples, blood draws, and clinical data. Using genetic and metabolomic analyses, the team focused on a subset of bifidobacteria capable of converting aromatic amino acids into aromatic lactates. They wanted to see whether specific diseases could be prevented by having a certain microbiota early in life.

Infants with a high abundance of these bacteria, particularly in the first 6 months of life, had elevated gut levels of aromatic lactates and a markedly lower risk of food allergen–specific IgE through age 5. Infants with high levels of bifidobacteria that produced aromatic lactate metabolites had reduced atopic dermatitis at 2 years old. The protective association was mediated by 4-hydroxy-phenyllactate (4-OH-PLA), a bacterial metabolite that selectively inhibited IgE production in ex vivo human immune cell cultures without affecting IgG.

“Even though that we see that [4-hydroxy-phenyllactate] can reduce IGE production…in human immune cell populations, we don't know exactly why,” said investigator Susanne Brix Pedersen, professor at DTU Bioengineering, in an interview with 

. “We know that humans, but not other animals except chimpanzees…have a specific receptor that can bind to these aromatic lactates, but we haven't been able to see that it's mediated via these receptors ye, so it might be other routes for interaction with the immune cells that has just not been discovered yet, but we do see this reduction.”

Early-life exposures strongly influenced whether infants acquired these bacteria. Vaginal delivery, exclusive breastfeeding during the first two months, and exposure to older siblings were all associated with higher colonization, with vaginally delivered infants up to 14 times more likely to acquire the strains from their mothers.

If confirmed, the findings could inform new preventive strategies—ranging from targeted probiotics to metabolite-enriched formulas—aimed at reducing the growing global burden of childhood allergies and asthma. Pedersen emphasized that this current data does not yet establish causality.

“There's no causal link at this moment,” Pederson said. “As I see it, we have this prospective study where we see associations, but we don't have any studies that have been designed to actually look at the causal interaction at this moment, but we are undertaking a bigger study in 1000 Danish infants, where we are trying to…investigate this in detail.”

Myers PN, Dehli RK, Mie A, et al. Early-life colonization by aromatic-lactate-producing bifidobacteria lowers the risk of allergic sensitization. 

Videos

Longitudinal data identify aromatic lactate–producing bifidobacteria and the metabolite 4-hydroxy-phenyllactate as key factors in early immune tolerance.

Susanne Brix Pedersen

Articles