According to researchers at Ohio State University, being around farm animals helps boost immunity, especially for babies and children. The researchers found that bacteria and other microbes from rural Amish babies was far more diverse—in a beneficial way—than what was found in the guts of urban babies. And, in a first-of-its-kind experiment, they found evidence of how a healthier gut microbiome might lead to more robust development of the respiratory immune system.
Study co-author Zhongtang Yu noted that although good hygiene is important, too much sanitization after some time can rob “our immune systems of the opportunity to be educated by microbes. Too clean is not necessarily a good thing.”
The research team collected fecal samples from 10 Ohio babies aged 6 months to a year old— five Amish babies all lived in rural homes with farm animals and five babies lived in a mid-size Ohio city, and had no known contact with livestock.
According to the researchers, the samples revealed important differences, such as a wide variation in microbes and an abundance of beneficial bacteria in the Amish babies’ guts that wasn’t found in their city-dwelling babies. “The priming of the early immune system is much different in Amish babies, compared to city dwellers,” said study co-author Renukaradhya Gourapura.
What they really wanted to know was how these differences might affect development of the immune system, setting the groundwork for a body’s ability to identify and attack diseases and its resistance to allergies and other immune-system problems. Previous studies in the U.S. Amish population and to comparable populations throughout the world have drawn a clear connection between rural life and a decrease in allergies and asthma, Gourapura said.
This connection has led to a theory called the “hygiene hypothesis,” which is built on the idea that hyper-clean modern life—eg, antibacterial soaps and ever-present hand sanitizers along with immaculately cleansed homes and workplaces—has led to an increase in autoimmune and allergic diseases.
In addition, the team of researchers wanted to explore how different gut microbiomes might contribute to immune system development. To do this, they used fecal transplants from the babies in the study to colonize the guts of newborn pigs.
“We wanted to see what happens in early immune system development when newborn pigs with ‘germ-free’ guts are given the gut microbes from human babies raised in different environments,” Gourapura said. “From the day of their birth, these Amish babies were exposed to various microbial species inside and outside of their homes.”
The researchers saw a connection between the diverse Amish gut microbes and a more-robust development of immune cells, particularly lymphoid and myeloid cells in the intestines. “Indeed, there was a big difference in the generation of critical immune cells,” Gourapura said.
Though the primary difference between the babies in the study was their exposure to a farming environment, another important difference that could contribute to gut microbiome differences between the groups is that the Amish families grew and routinely ate their own produce.
Reference:
Dhakal, et al. “Amish (Rural) vs. non-Amish (Urban) Infant Fecal Microbiotas Are Highly Diverse and Their Transplantation Lead to Differences in Mucosal Immune Maturation in a Humanized Germfree Piglet Model.” Frontiers in Immunology, 2019; 10 DOI: 10.3389/fimmu.2019.01509
