Poorer socioeconomic conditions are linked to worse health outcomes, but the biological reasons are not fully understood. New research now shows that breastfeeding helps shape a healthy infant gut microbiota and can partly offset the negative effects of lower socioeconomic status on children’s long-term health.

The findings, published in Cell Reports Medicine, suggest that improving access to breastfeeding and supporting healthy infant gut microbes could be a way to reduce health inequalities linked to socioeconomic disadvantage.

Modern lifestyles, such as antibiotics, diet, and sanitation, have changed our microbiotas. Since early-life gut bacteria are shaped partly by the environment—which is influenced by a person’s socioeconomic status, the microbiota may be the missing link connecting social inequality to health differences.

To better understand how socioeconomic status affects child health, Darlene Dai at the University of British Columbia in Vancouver, Canada, and her colleagues examined early-life conditions, infant gut bacteria, breastfeeding, and health outcomes at age five in a group of about 3,400 children.

Breastfeeding benefits

Children from families of higher socioeconomic status generally had lower risks of conditions such as obesity, asthma, and behavioral problems. Some factors—including longer breastfeeding—were associated with better outcomes, whereas early antibiotic use or maternal stress were linked to worse outcomes.

Babies from different socioeconomic backgrounds have different gut bacteria patterns, especially in the first months of life. Breastfeeding, which shapes the infant gut microbiota, was found to be the main factor linking socioeconomic status to gut bacteria differences. Families of higher socioeconomic status breastfeed more than families of lower socioeconomic status, and exclusive breastfeeding lowered the risk of obesity, asthma, or behavioral issues. 

One key species, Bifidobacterium infantis, was more common in breastfed infants and was associated with better health outcomes. However, this beneficial bacterium is relatively rare in industrialized societies, the authors note.

Beneficial bacteria

In general, higher levels of beneficial bacteria—especially B. infantis and certain Bacteroides species—were linked to reduced risks of obesity, asthma, and behavioral problems, while lower levels of these beneficial microbes and higher levels of species such as Clostridium innocuum were associated with increased risks.

To confirm these findings, the researchers repeated the analysis in a separate group of families in Denmark and found similar patterns. Higher socioeconomic status was linked to better child health, and breastfeeding played a key role in shaping the microbiota and reducing risks. 

“Together, these findings suggest that supplementation with key beneficial bacteria, alongside efforts to reduce breastfeeding barriers, may offer scalable strategies to improve child health and reduce socioeconomic health disparities,” the authors say.