The Ecosystem in Immigrants’ Guts Is Shaped by the Place They Call Home

Bodies that migrate across borders undergo tremendous change.

Immediately, feet alight on alien terrain, ears channel novel sounds, and noses inhale unfamiliar scents.

More gradually, daily routines fall under new rhythms, cultural norms hybridize and dreams evolve.

Another transformation occurs deep within the body two recent studies from the Netherlands and we find because the trillions of microbes that sleep in the human gastrointestinal system shift in composition.

While many factors may influence how this alteration occurs, the studies suggest that scientists should consider individuals’ migration status and ethnic origin as they aim for clinical interventions supported the gut microbiome.

Researchers try to know what governs gut microbial composition, partially due to increasing evidence that the trillions of microorganisms teeming in our guts influence health in myriad ways.

Most chronic diseases are tied to deviations within the gut microbiome, though the specifics of cause and effect still got to be parsed out.

The first study, published in Nature Medicine in August, compared the gut microbiomes of adults from Amsterdam’s six largest ethnic groups.

The team led by Mélanie Deschasaux, an epidemiologist at the tutorial center in Amsterdam, assessed stool samples from 2,084 individuals who were ethnically Dutch, Ghanaian, Moroccan, Turkish, African Surinamese or South Asian Surinamese.

Most of the non-Dutch participants had immigrated to the Netherlands as adults.

Between ethnic groups, the researchers discovered significant differences in overall gut microbe composition. Of the varied factors studied, ethnicity was the strongest

the determinant of gut microbial makeup.

Across the Atlantic, Pajau Vangay and Dan Knights, of the University of Minnesota, worked with two local communities to review how migration alters the human gut microbiome. They published their leads to Cell last week.

One community, the Hmong, began arriving in Minnesota within the 1970s as refugees from the CIA-backed Secret War and Vietnam War, which ravaged their communities in Laos.

The second group, the Karen, arrived in Minnesota in larger numbers within the past decade, fleeing human rights abuses in Myanmar.

Stool samples and other data from quite 500 women revealed that immigrants from these groups began losing their native microbes soon after resettling.

They picked up American microbes, but “not enough to catch up on the loss of native strains, in order that they find yourself losing a considerable amount of diversity overall,” Dr. Knights said.

Furthermore, losses were greater in obese individuals and youngsters of immigrants.

Dr. Vangay, a second-generation Hmong immigrant, partnered with Kathie Culhane- Pera, a general practitioner, to involve Hmong and Karen community researchers.

Together with the teachers, the community researchers developed the study’s design, recruitment methods, and methods for sharing results.

Separately, advisory boards of Hmong and Karen health professionals and community leaders gave input, leading to a project conducted largely by and for the communities it studied, said Houa Vue-Her, a Hmong planning board member.

The study wouldn't have worked otherwise, she added. Some Hmong with traditional spiritual beliefs might resist giving samples for laboratory testing, as an example, out of fear that it might interfere with reincarnation.

Lingering trauma from the wars and therefore the federal government’s secrecy might prevent many others from trusting outsiders.

The most obvious culprit behind the loss of native gut microbes is diet.

Alongside native gut flora, immigrants lost enzymes linked to digesting tamarind, palm, coconuts and other plants are commonly eaten in Southeast Asia, the study found.

The longer immigrants lived in Minnesota, the more their gut microbiomes shifted to at least one reflective of a typical American diet high in sugars, fats, and protein.

But diet alone couldn't explain all of the changes, Dr. Knights said. Other factors might include antibiotic medications, different birthing practices, and other lifestyle changes.

What Does Your Microbiome Say About You?

There are many, many microbial species living in or on your body?

What secrets can they tell? Dr. Deschasaux noted that her study and Dr. Vangay’s reach somewhat contrasting findings.

While she found that immigrants maintained ethnic-specific microbiome profiles, even after decades in Amsterdam, Dr. Vangay found that the gut microbiomes of Hmong and Karen immigrants steadily assimilated to their new locale.

The divergence might relate to differences in typical Dutch and American diets with

perhaps less sugar, fat and meat, and more raw vegetables in Dutch diets — and possibly lower rates of acculturation by the Dutch immigrants compared with Hmong and Karen refugees, Dr. Deschasaux speculated.

Yet both studies have implications for health disparities. Obesity, diabetes, and metabolic syndrome all are linked to the gut microbiome, and therefore the ethnic groups Dr. Deschasaux studied in Amsterdam experience varying degrees of those conditions.

Compared to the ethnic Dutch, as an example, Dutch Moroccans in her study had a better prevalence of obesity, and therefore the South-Asian Surinamese had a better prevalence of type 2 diabetes and metabolic syndrome.

Similarly, research has shown that living within us increases the danger of obesity among immigrants and Southeast Asian refugees are particularly vulnerable.

“It was actually a challenge finding participants who fell within the normal range of body mass index for the study,” said Mary Xiong, a second-generation Hmong American and a community researcher within the Minnesota project.

“That opened my eyes about what proportion of a priority this is often .”

That urgency partially motivated Dr. Vangay and her collaborators to relay their results back to community members.

“Many of those communities aren't even aware that the gut microbiome exists,” Dr. Vangay said.

In some ways, she added, “our best recommendation to community members was to carry onto their roots.”

As an example, the researchers partnered with Yia Vang, co-founder of Union Kitchen, a Minnesota-based Hmong pop-up restaurant, to hold cooking workshops for the Hmong community.

One of the dishes that participants made was zaub qaub, or fermented mustard.

In addition to being full of probiotics, zaub qaub “is one among the foremost iconic Hmong dishes,” as kimchi is to Koreans, Mr. Vang said.

“When I eat it, I’m partaking within the history of our people. the flavor I’m eating is that the same flavor my great-great-grandmother ate on the hills of Laos.”