A recent study by University of Minnesota researchers discovered immigration to the U.S. can rapidly change the bacteria found in a person’s gut — findings that may shed light on the causes of high obesity rates in immigrant communities.

The study, published on Nov. 1, looked at Southeast Asian immigrant communities in Minnesota, including Hmong and Karen communities from Thailand. The researchers were aided by the Somali, Latino and Hmong Partnership for Health and Wellness and advisors from in the community.

“The Hmong community and Karen community don’t get enough attention to study what is impacting our health and what’s causing obesity, which leads to diabetes,” said Houa Vue-Her, a diabetes initiative program director at Blue Cross and Blue Shield of Minnesota, who served as a community advisor to researchers.

The results of the study show a rapid Westernization of immigrants’ gut microbiomes — the environment of microbes like bacteria and fungi in an individual’s stomach — when they migrated to the U.S.

“The strains of bacteria that used to dominate their gut were going missing and they were acquiring American strains,” said Dan Knights, an author of the study and a computational microbiologist at the University. “When they lost those native strains, they were losing genes that seemed to be involved in digesting certain foods that are more commonly eaten in Southeast Asia.”

Stool samples were taken and analyzed from over 500 Hmong and Karen individuals, including those who immigrated to the U.S., as well as children born in the U.S., people still living in Thailand and Caucasians, which served as the control group. Six individuals were also sampled before and after immigrating to the U.S, said Pajau Vangay, a research specialist in the University’s Biomedical Informatics and Computational Biology program and a co-author of the study. 

Vangay worked with community members to recruit individuals who would take part in the study and traveled to Thailand to collect samples from native Hmong and Karen people.

The research could help to explain health issues affecting immigrant communities, including obesity and diabetes.

“We realized that obesity was a really big concern,” Vangay said. “From a scientific perspective, there are a lot of associations with, and some causal inferences between, the gut microbiome and obesity.”

But researchers cautioned the correlation between a Westernized microbiome in the gut and rates of obesity in the immigrant community does not necessarily reflect a cause-and-effect relationship. 

“This is really the first chapter in the story,” Knights said. “The next step is finding out which of these changes are actually bad for you and, if they are, how we can use the microbiome to treat or prevent obesity.”