Immigration to the United States changes a person's microbiome

November 01, 2018

Researchers at the University of Minnesota and the Somali, Latino, and Hmong Partnership for Health and Wellness have new evidence that the gut microbiota of immigrants and refugees rapidly Westernize after a person's arrival in the United States. The study of communities migrating from Southeast Asia to the U.S., published November 1 in the journal Cell, could provide insight into some of the metabolic health issues, including obesity and diabetes, affecting immigrants to the country.

"We found that immigrants begin losing their native microbes almost immediately after arriving in the U.S. and then acquire alien microbes that are more common in European-American people," says senior author Dan Knights, a computer scientist and quantitative biologist at the University of Minnesota. "But the new microbes aren't enough to compensate for the loss of the native microbes, so we see a big overall loss of diversity."

It has been shown before that people in developing nations have a much greater diversity of bacteria in their gut microbiome, the population of beneficial microbes living in humans' intestines, than people living in the U.S. "But it was striking to see this loss of diversity actually happening in people who were changing countries or migrating from a developing nation to the U.S.," he says.

The research was conducted with assistance from--and inspired by--Minnesota's large community of refugees and immigrants from Southeast Asia, particularly the Hmong and Karen peoples, ethnic minorities that originally were from China and Burma and that today have communities in Thailand. The study used a community-based participatory research approach: members of the Hmong and Karen communities in both Minnesota and Thailand were involved in designing the study, recruiting participants, and educating their communities about the findings.

"Obesity was a concern that was coming up a lot for the Hmong and Karen communities here. In other studies, the microbiome had been related to obesity, so we wanted to know if there was potentially a relationship in immigrants and make any findings relevant and available to the communities. These are vulnerable populations, so we definitely try to make all of our methods as sensitive to that as possible and make sure that they have a stake in the research," says first author Pajau Vangay.

Knights, Vangay, and their team compared the gut microbiota of Hmong and Karen people still living in Thailand; Hmong and Karen people who had immigrated to the U.S.; the children of those immigrants; and Caucasian American controls. They also were able to follow a group of 19 Karen refugees as they relocated from Thailand to the U.S., which meant they could track how the refugees' gut microbiomes changed longitudinally in their first six to nine months in the U.S.

And the researchers did find that significant changes happened that fast: in those first six to nine months, the Western strain Bacteroides began to displace the non-Western bacteria strain Prevotella. But this Westernization also continued to happen over the course of the first decade in the U.S., and overall microbiome diversity decreased the longer the immigrants had been in the U.S. The participants' food logs suggested that eating a more Western diet played a role in perturbing the microbiome but couldn't explain all the changes.

The changes were even more pronounced in their children. "We don't know for sure why this is happening. It could be that this has to do with actually being born in the USA or growing up in the context of a more typical US diet. But it was clear that the loss of diversity was compounded across generations. And that's something that has been seen in animal models before, but not in humans," says Knights.

Although the research didn't establish a cause-and-effect relationship between the microbiome changes in immigrants and the immigrant obesity epidemic, it did show a correlation: greater westernization of the microbiome was associated with greater obesity.

Knights believes that this research has a lot to tell us about our health. "When you move to a new country, you pick up a new microbiome. And that's changing not just what species of microbes you have, but also what enzymes they carry, which may affect what kinds of food you can digest and how your diet interacts with your health," he says. "This might not always be a bad thing, but we do see that Westernization of the microbiome is associated with obesity in immigrants, so this could an interesting avenue for future research into treatment of obesity, both in immigrants and potentially in the broader population."
-end-
This research was supported by the Clinical and Translational Science Institute, the Healthy Foods, Healthy Lives Institute, the Office of Diversity, and the Graduate School at the University of Minnesota.

Cell, Vangay et al.: "U.S. immigration westernizes the human gut microbiome" https://www.cell.com/cell/fulltext/S0092-8674(18)31382-5

Cell (@CellCellPress), the flagship journal of Cell Press, is a bimonthly journal that publishes findings of unusual significance in any area of experimental biology, including but not limited to cell biology, molecular biology, neuroscience, immunology, virology and microbiology, cancer, human genetics, systems biology, signaling, and disease mechanisms and therapeutics. Visit: http://www.cell.com/cell. To receive Cell Press media alerts, contact press@cell.com.

Cell Press

Related Obesity Articles from Brightsurf:

11 years of data add to the evidence for using testosterone therapy to treat obesity, including as an alternative to obesity surgery
New research covering 11 years of data presented at this year's European and International Congress on Obesity (ECOICO 2020) show that, in obese men suffering from hypogonadism (low testosterone), treatment with testosterone injections lowers their weight and improves a wide range of other metabolic parameters.

Overlap between immunology of COVID-19 and obesity could explain the increased risk of death in people living with obesity, and also older patients
Data presented in a special COVID-19 session at the European and International Congress on Obesity (ECOICO 2020) suggests that there are overlaps between the immunological disturbances found in both COVID-19 disease and patients with obesity, which could explain the increased disease severity and mortality risk faced by obese patients, and also elderly patients, who are infected by the SARS-CoV-2 virus that causes COVID-19 disease.

New obesity guideline: Address root causes as foundation of obesity management
besity management should focus on outcomes that patients consider to be important, not weight loss alone, and include a holistic approach that addresses the root causes of obesity, according to a new clinical practice guideline published in CMAJ (Canadian Medical Association Journal) http://www.cmaj.ca/lookup/doi/10.1503/cmaj.191707.

Changing the debate around obesity
The UK's National Health Service (NHS) needs to do more to address the ingrained stigma and discrimination faced by people with obesity, says a leading health psychologist.

Study links longer exposure to obesity and earlier development of obesity to increased risk of type 2 diabetes
Cumulative exposure to obesity could be at least as important as actually being obese in terms of risk of developing type 2 diabetes (T2D), concludes new research published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD]).

How much do obesity and addictions overlap?
A large analysis of personality studies has found that people with obesity behave somewhat like people with addictions to alcohol or drugs.

Should obesity be recognized as a disease?
With obesity now affecting almost a third (29%) of the population in England, and expected to rise to 35% by 2030, should we now recognize it as a disease?

Is obesity associated with risk of pediatric MS?
A single-center study of 453 children in Germany with multiple sclerosis (MS) investigated the association of obesity with pediatric MS risk and with the response of first-line therapy in children with MS.

Women with obesity prior to conception are more likely to have children with obesity
A systematic review and meta-analysis identified significantly increased odds of child obesity when mothers have obesity before conception, according to a study published June 11, 2019 in the open-access journal PLOS Medicine by Nicola Heslehurst of Newcastle University in the UK, and colleagues.

Obesity medicine association announces major updates to its adult obesity algorithm
The Obesity Medicine Association (OMA) announced the immediate availability of the 2019 OMA Adult Obesity Algorithm, with new information for clinicians including the relationship between Obesity and Cardiovascular Disease, Diabetes Mellitus, Dyslipidemia, and Cancer; information on investigational Anti-Obesity Pharmacotherapy; treatments for Lipodystrophy; and Pharmacokinetics and Obesity.

Read More: Obesity News and Obesity Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.