Human microbiome could shed light on higher morbidity rate in minoritized populations

Study into environment and health calls for equal health opportunities

Differences in socio-economic backgrounds and living environments can lead to different disease pathologies and unequal health opportunities. That is the conclusion published by an international group of scientists in this week’s issue of the journal PNAS. The team calls for further research into the issue by examining the composition of microorganisms in the intestines. The group included scientists from Radboudumc and Utrecht University.

In their publication, the researchers explain how minority groups are structurally exposed to unhealthy factors in the environment. Some examples include unhealthy eating habits, more pollution in the vicinity, differences in sanitary facilities and lack of access to green spaces outdoors. All of these aspects can affect the composition of microorganisms in the intestines, collectively known as the ‘gut microbiota’.

The environment's influence on the microbiome can eventually have major consequences for the health of the entire body.

Important role for microbiome

The influence on the microbiome can eventually have major consequences for the health of the entire body. The microbiome plays a vital role in protecting against pathogens, nutrition and metabolism, our immune system, and the development of our brain and behaviour.

Countless other studies support the idea that the living environment exerts an influence on the microbiome, and that the microbiome influences our health. The new study builds on previous research indicating that the living environment plays a major role in the composition of bacteria that nestle in our microbiome. In fact, the living environment plays an even greater role than genetic factors. And it does so from a very early age in children.

“Changes to the microbiome are related to a large number of pathologies, which are not just limited to the intestines”, says Carlijn Bruggeling, affiliated with Radboudumc. “Via metabolites, toxins and the immune system, the microbiome can also have an impact on things like a healthy pregnancy or mental health and depression.”

Minoritized populations living in neighborhoods with little access to outdoor green space are more likely to have lower microbial diversity

Living environment and health risks

Previous studies have already proven the influence of differences in socio-economic background and the living environment on health. A study from 2020, for example, showed that children who are exposed to plants and soil every day at school have better immunological markers, which is linked to greater microbial diversity.

The study also found a negative correlation between the living environments of minority groups and the microbial diversity of the microbiome. Minority groups that live in neighbourhoods with little access to green spaces outdoors are more likely to have a limited microbial diversity, and the health risks that are associated with that

“We’ve known for a while that there are inequalities in many chronic diseases, and that minority groups are more likely to suffer more severe symptoms and even death”, says Katharine Amato, who led the study from Northwestern University in the United States.

Equal health opportunities

Nevertheless, the correlations between income, structural discrimination, changes in the environment and differences in health outcomes have not yet been thoroughly studied and summarised. The new research published in PNAS has changed that.

An interdisciplinary approach is needed because many factors can influence our health and condition

In response to the recent publication, the team has also called for more interdisciplinary research to find out which environmental factors should be addressed first in order to allow the microbiome to quickly recover and improve, and therefore give everyone equal health opportunities.

An interdisciplinary approach is needed because many factors can influence our health and condition, explains Bas Dutilh, biologist at Utrecht University and co-author of the PNAS publication. “This is sometimes described using the word ‘exposome’; or all of the things we are exposed to. Using new technologies like DNA sequencing, we can now measure all of those factors and identify how they work. The microbiome is one of the most important parts of the exposome, but there are more factors that play a role as well.”


The human gut microbiome and health inequities

Proceedings of the National Academy of Sciences, 22 juni 2021, DOI: 10.1073/pnas.2017947118

Katherine R. Amatoa, Marie-Claire Arrieta, Meghan B. Azad, Michael T. Bailey, Josiane L. Broussard, Carlijn E. Bruggeling, Erika C. Claudj, Elizabeth K. Costello, Emily R. Davenport, Bas E. Dutilh*, Holly A. Swain Ewald, Paul Ewald, Erin C. Hanlon, Wrenetha Julion, Ali Keshavarzian, Corinne F. Maurice, Gregory E. Miller, Geoffrey A. Preidis, Laure Segurel, Burton Singer, Sathish Subramanian, Liping Zhao and Christopher W. Kuzawa

*: Researcher at Utrecht University