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Breastfed Babies’ Immune Cells Mature Faster in Farm Environments

    Two children smiling as they touch a baby lamb in a grassy field against a wooden fence to illustrate the findings of a new study correlating the maturing rate of B cells for children from urban versus rural environments.

    Written by: Jyoti Madhusoodanan, Ph.D. | Issue # 132 | 2026

    • Families who live farming lifestyles have lower risk of asthma and food allergies.
    • B cell maturity and infants’ antibody response may play a protective role against developing allergies.
    • IgA and IgG responses to dairy, egg and other common allergens were stronger in rural residents raised on mother’s milk.
    • Living a farming or rural lifestyle appears to accelerate immune development in breastfed babies compared to an urban or suburban lifestyle.

    Asthma and other allergic conditions are a growing public health concern globally. Within the U.S., estimates suggest that 8 percent of school-aged children live with food allergies and must avoid milk, eggs, peanuts or other common triggers. 

    The environment is thought to play a significant role in the development of allergies. Researchers have found that children who live in industrial or urban environments have higher rates of asthma and allergies than those who live a rural or farming lifestyle. Exposure to a farming lifestyle and close proximity to animals alters the composition of mother’s milk,  which in turn modulates the development of an infant’s gut microbiome and innate immune system and  influences the risk of allergies. 

    But little is known about how antibodies—another key immune regulator in maternal milk—can influence the risk of food allergies in babies. Some studies have suggested that IgA, the major antibody in breastmilk, may have a protective effect, while others have reported higher IgA levels in infants with allergies. “It’s been conflicting evidence,” said immunologist Kirsi Järvinen of the University of Rochester. “It hasn’t been a straightforward story.” 

    As part of her doctoral research, Järvinen  found that breastmilk IgA might protect against cow’s milk allergies. In a new study, Jarvinen and her colleagues set out to explore the relation between antibodies in milk and food allergies in infants [1]. 

    The researchers recruited participants from urban and suburban communities in Rochester, New York, and from an Old Order Mennonite community in the region, who live a traditional farm lifestyle. The team collected cord blood and peripheral blood samples as well as stool, saliva and maternal milk during pregnancy and the first year after birth to gauge antibody responses and the development of antibody-producing B cells. 

    The researchers found no significant difference in the levels of B cells measured in infants from farming environments and those from urban settings. But the proportions of different types of B cells differed: at 12 months of age, infants from the rural community had higher proportions of memory B cells and lower levels of naïve B cells, indicating a more mature immune system compared to infants from urban homes. 

    The researchers also tested levels of circulating antibodies and found that infants living on farms had significantly higher levels of circulating IgA and IgG compared with urban infants at 6 months and 12 months of age. Infants also differed in the antibodies’ reactivity – rural infants had higher levels of antibodies against house dust mites and horse allergens, while urban babies had stronger antibody reactions to peanuts and cats. Children from farming communities had higher levels of IgG antibodies against egg proteins by the age of 6 months and at 12 months. These antibodies may be protective against egg allergies—which are the most common food allergy in urban children by the age of two, the researchers said. 

    The researchers also looked for differences in mucosal immunity, measured by the levels of IgA antigens in saliva and stool samples. They found that the farming lifestyle was correlated with higher levels of IgA early in life. Maternal milk is a major source of IgA for newborns, and at 6 weeks postpartum, mothers from rural communities had higher levels of milk IgA than those who lived in urban areas. Although B cells matured and antibodies developed in all participants, the process “took longer” in urban babies, Järvinen said. “We concluded that the farming lifestyle is associated with an accelerated development of immunity.”

    The researchers also compared the immune profile of urban participants who developed allergies with those who did not, finding  that children who developed allergies were more likely to have lower levels of antibodies. Overall, the cohort appeared to cluster into three groups – with the highest antibody levels and lowest rates of allergies in the farm-dwelling children, and the lowest antibody levels in urban infants who developed allergies, Jarvinen said. 

    Allergies occur due to many factors, including the microbiome and environmental exposures, so antibody levels alone cannot predict whether an infant is at risk of developing allergies, Järvinen said. However, she added, data such as these could inform future studies that reveal ways to boost maternal immunity – and reduce a baby’s odds of food allergies — during pregnancy or lactation with dietary changes. “Prevention is where this is going to have the biggest impact,” Järvinen said. 

    References

    1. Jackson CM, Ponko E, Vance NM, Davis EC, Mahmood MM, Valderrama-Hincapié C, Diaz NS, Vanasse L, Looney RJ, Thakar J, Seppo AE. Farm exposure in infancy is associated with elevated systemic IgG4, mucosal IgA responses, and lower incidence of food allergy.. Sci Transl Med. 2025 Dec 10;17(828):eads1892.