Recent evidence from the University of Minnesota in conjunction with the Somali, Latino, and Hmong Partnership for Health and Wellness suggested that immigrants and refugees moving to the United States were likely to experience a rapid change in their gut microbes. Described as “westernizing” to their environment, immigrants tended to lose their diverse, native microbes in favor of microbes that are common to European Americans.

The participants of this study originated from Southeast Asia, specifically the ethnic minorities of Hmong and Karen from China, Burma, and Thailand. The study used ethnic minority communities from both Southeast Asia as well as those living in Minnesota as a comparison, analyzing the gut microbes in these participants and using Caucasian American people as controls. The researchers also looked into the first generation children of these immigrants. Additionally, the study was able to follow a group of nineteen Karen refugees, tracking the changes in their gut microbes as they traveled to the United States.

The study discovered that the gut microbes in these participants changed rapidly. Particularly, in the group of Karen refugees, the Western strain of Bacteriodes replaced the non-Western strain of Prevotella in the matter of less than a year. Furthermore, the overall gut microbe diversity continued to decrease in all participants in the United States in relation to the length of their stay. Likewise, the children of immigrants had a more profound decrease in diversity. Researchers in this study suggested that this decrease in microbe diversity may have been a result of a Western diet, or for the children, growing up in the United States.

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Closeup of Bacteroides biacutis(Image Credit: CDC/Dr. V.R. Dowell)


So why does this matter? Well, the study established a correlation: the greater the “westernization” of gut microbes, the greater obesity in immigrants. This obesity problem appeared to be more prevalent in immigrants, and the study had discovered a key piece of evidence for why.

“When you move to a new country, you pick up a new microbiome.” Dan Knights, one of the key authors of the study as well as a quantitative biologist at the University of Minnesota, says. “…What enzymes they carry…may affect the kinds of food you can digest and how your diet affects your health. This may not be a bad thing, but we do see that Westernization of the microbiome is associated with obesity in immigrants.”


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