Researchers from the University of Minnesota and the Somali, Latino, and Hmong Partnership for Health and Wellness have published a new study in the journal Cell which provides evidence that the microbiome of immigrants can make a dramatic shift after they come to the United States. More specifically, the study looked at the microbiome of Hmong and Karen immigrants. These are ethnic minorities who originated in Southeast Asia.
Essentially, the study showed that immigrants from this area may have started with diverse microbiomes but after shifting to a very American diet, this diversity all but disappeared. And with that, the researchers say that this could explain the rise in obesity rates within immigrant communities.
More specifically, the study compared the digestive bacteria in 514 Hmong and Karen women with the digestive bacteria of 36 white women who live in the US Midwest; Minnesota, to be exact. Some of these Hmong and Karen women had recently immigrated to the Twin Cities while some remained in Southeast Asia, and others were US-born children of other immigrants.
The study found that within 6 and 9 months of arriving in the US, the immigrant women saw a drop in both number and diversity of gut bacteria.
Unfortunately, the study details that native microbiomes disappeared almost immediately upon introducing American food; and then soon after, these immigrants would quickly acquire microbes which are more commonly known in European-Americans. The dominant species of gut bacteria changed from Prevotella to Bacteroides. But while these immigrants were definitely developing new microbes, the researchers found that what they developed could not compensate for the loss of the [far more diverse] native microbes.
This study is important, of course, because existing obesity surveys—most of the time, anyway—only ask if people are Asian (or other races). As such, there is little data that can prove if there is, specifically, a rising issue facing Hmong Americans. With this new study, then, they were able to more closely examine that 35 percent of Hmong high school juniors—in Minnesota—were either overweight or obese, compared with only 24 percent of white juniors.
Of course, there was never really any reason to doubt Asian immigrants would be vulnerable to obesity issues because of dietary changes. After all, Asian natives consume a diet that is heavy in vegetables and rice while the typical American eats food that is typically higher in fats and carbohydrates.