What is already known on this topic
The gut microbiota has been linked to several diseases, including diabetes and cancer, and researchers have proposed manipulating gut microbes as a therapeutic approach. But first it’s important to understand what a healthy gut microbiota looks like and how it varies across different ethnicities.
What this research adds
The researchers analyzed the gut microbiota composition of nearly 1,700 healthy people in the United States and discovered 12 particular types of bacteria that vary in abundance by ethnicity.
The study emphasizes the need to consider ethnic diversity in microbiota research. Understanding how the gut microbiota varies across different ethnicities could help to advance microbial-based treatments.
The gut microbiota differs among ethnic groups in the United States, researchers have found. The study, led by Andrew Brooks at Vanderbilt University in Nashville, Tennessee, was published in the journal PLOS Biology.
Gut-dwelling bacteria have been linked to a range of diseases, from diabetes to cancer to inflammatory bowel disease. For this reason, researchers have proposed changing the gut microbiota as a therapeutic strategy. To do so, however, it’s key to define what a healthy gut microbiota is and how it varies across different ethnic groups.
What’s more, many common diseases are associated with microbiota composition and ethnicity, suggesting that microbiota differences between ethnicities could mediate health disparities.
To address whether ethnicity could explain the variation in gut microbiota among individuals, the researchers have examined connections between self-declared ethnicity and gut microbiota differences across 1,673 healthy people in the United States.
Twelve bacteria families vary by ethnicity
The researchers analyzed gut microbiota samples from the American Gut Project and the National Institutes of Health’s Human Microbiome Project, two research initiatives whose goal is to better understand the human microbiota. The sampled individuals had self-declared as either Asian-Pacific Islanders or Caucasians or Hispanics or African Americans.
First, the team assessed whether gut microbiota could be distinguished between ethnicities, sexes, age groups, and body mass indexes (BMI). Although the more prominent differences were observed between individuals, the researchers could distinguish gut microbes according to ethnicity, BMI, and sex, but not according to age.
Bacteria from the Firmicutes and Bacteroidetes families dominated the total gut microbiota across ethnicities, but the researchers found 12 particular bacteria families that vary in abundance by ethnicity. These bacteria families are Christensenellaceae, Clostridiales, Coriobacteriaceae, Dehalobacteriaceae, Odoribacter, Odoribacteriaceae, Peptococcaceae, RF39, Rikenellaceae, Veillonella, Verrucomicrobiaceae, and Victivallaceae.
For example, bacteria from the Clostridiales and Odoribacteriaceae families as well as the Odoribacter genus are more abundant in Caucasians and Hispanics compared to Asian-
Pacific Islanders, whereas Veillonella is more abundant in African Americans than in Caucasians and Hispanics.
The Christensenellaceae family, which has been identified as the most heritable bacterial family in the human gut, differs in abundance across ethnicities, sex, and BMI. In Asian-Pacific Islanders, for instance, bacteria from the Christensenellaceae family are significantly less abundant than in other ethnicities. In African Americans, Asian-Pacific Islanders, and Caucasians, but not Hispanics, people with Christensenellaceae also have a lower BMI than individuals without it.
Most bacterial families have been associated with genetic variations
In summary, although sex and BMI could be associated with differences in gut microbes, ethnicity more consistently explained the gut microbiota variation across individuals. The authors say that ethnicity could be moderately predicted from gut microbiota differences and that most of the 12 bacterial families that vary in abundance across ethnicities have been associated with human genetic variation. This suggests that a connection between ethnicity and genetic patterns of ancestry may shape the gut microbiota composition.
By highlighting the importance of taking into account ethnic diversity in studies on microbiota and disease, the study offers a framework for understanding microbiota differences among people and addressing health disparities.