COLUMBUS, Ohio — Looking to expand your family with some pets? Consider taking on chickens or goats. A study of gut microbes collected from Amish babies, who are raised around a variety of livestock, showed they are much more diverse — in a good way — than the gut microbes of urban babies. This suggests, according to researchers at Ohio State University, that early exposure to a wider variety of environmental bacteria, including those found in and on livestock, leads to health and immune system benefits later in life.
Furthermore, in a first-of-its-kind experiment, the research team was able to gather evidence that a healthy, diverse gut microbiome might lead to better development of the respiratory immune system. If you’re one of those parents quick to squirt a dollop of hand sanitizer on your children’s palms after visiting a petting zoo, experts suggest considering the other side of the coin.
“Good hygiene is important, but from the perspective of our immune systems, a sanitized environment robs our immune systems of the opportunity to be educated by microbes. Too clean is not necessarily a good thing,” says co-lead author Zhongtang Yu in a release. Yu is a professor of microbiology in Ohio State’s Department of Animal Sciences.
Researchers collected fecal samples from 10 babies in Ohio, all between six months to a year old. Five were Amish babies living in rural homes with farm animals. The other five lived in or near the mid-sized city of Wooster and had no known contact with livestock.
Upon analyzation, the stool samples revealed many important differences. There was a big variation in microbes between the urban and rural babies. More specifically, there was a large amount of beneficial bacteria present in the Amish babies’ intestines that wasn’t found in the urban babies’ samples.
Yu and his team say they expected to see these differences, due to the plain-to-see fact that Amish live beside livestock and just live a less sanitary lifestyle in general than most other people. However, what they were really after was how these microbiome differences affect immune system development and help prepare the body to identify and attack diseases, and protect itself against allergies and other problems later on in life. Prior research has already found Amish population samples to exhibit lower allergy and asthma rates.
All of this data indicating that it is actually a good thing to get dirty every now and then has led to the formulation of the “hygiene hypothesis,” which states autoimmune and allergic diseases are currently on the rise because more and more people are living a hyper-clean lifestyle.
There are trillions of microbes in the human gut known to play a role in one’s overall health and protection from disease. So, with this in mind, researchers wanted to investigate how different gut microbiomes individually contribute to immune system health and development. To accomplish this, they took the stool samples taken from babies and colonized 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,” says professor Renukaradhya Gourapura, co-lead author on the study. “From the day of their birth, these Amish babies were exposed to various microbial species inside and outside of their homes.”
Gourapura and his team observed a connection between the arrival of Amish gut microbiomes and enhanced immune cell development in the pigs, specifically lymphoid and myeloid intestinal cells.
“Indeed, there was a big difference in the generation of critical immune cells,” Gourapura comments.
There had already been previous research conducted on the connection between immunity and the microbiome in mice, but this study showed that pigs can be used for research purposes as well. This is especially noteworthy because pigs have a similar anatomy, genetics, immune system, and physiology to humans.
“Researchers know that the gut microbiome likely plays a significant role in development of the immune system and in the onset of various metabolic processes and infectious diseases, but we need better models to discover the details of that process so that we can use that information to improve human health,” Gourapura says.
For example, future research performed on pigs may be able to identify specific probiotics that can improve gut health and immune development.
As far as other explanations for the gut microbiome differences among the two groups of babies, researchers did note that Amish families typically growing and eating their own produce may have played a role. Additionally, two of the babies in the urban group had only been formula-fed, while all the babies in the amish group had been breast fed.
The study is published in the journal Frontiers in Immunology.