In each human gut, a community of trillions of bacteria help digest food and make certain nutrients. Some of these bacteria are associated with disease such as diabetes and Crohn’s, while some prevent disease. The composition of bacteria varies from one person to another, with diet and geographical location contributing to the diversity. In modern times, where millions of people migrate around the globe, their gut bacteria migrate with them. What happens to their bacteria when they move to a different country with a drastically different diet and lifestyle? Can their microbiome assimilate to the new culture?

Researchers analyzed gut bacteria of Hmong and Karen refugees from Thailand before and after they immigrated to the US. In as little as nine months after they moved, the refugees’ gut bacteria became Westernized. Bacteroides strains, prevalent among US residents, rapidly displace Prevotella strains prevalent among Thailand residents. This new gut microbiome is less capable of digesting fiber and less diverse, containing fewer species of bacteria. Low bacterial diversity has also previously been associated with a high rate of obesity.

This research looked at correlation and did not directly show that immigration cause the change in bacterial diversity or whether the change directly causes obesity. Nevertheless, the research shows that immigration may not only take a toll on people but also on their gut bacteria, which can in turn influence the body’s overall health. Gaining a better understanding of how our microbiome changes as we relocate might allow us to improve the health of immigrants and refugees, preventing them from becoming obese in a new country. It could also help us design a better Western diet to maintain ‘good’ bacteria species and a more diverse gut microbiome.

Managing Correspondent: Veerasak (Jeep) Srisuknimit

Original Paper: Cell

Press Article: Cell Metabolism

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Image Credit: Wikimedia

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