News
When it comes to brain health, is microbiome science missing much of the world?
For more than two decades, scientists have uncovered remarkable links between the trillions of microbes living in our gut and the health of our brains. This research has transformed our understanding of stress, depression, anxiety and neurodevelopment, opening new possibilities for preventing and treating mental illness. What if much of this science is based on studying only a narrow slice of global diversity?
Published today in Nature Mental Health, a new international perspective led by researchers at APC Microbiome Ireland in University College Cork (UCC) argues that one of the biggest obstacles facing microbiome and mental health research is not a lack of technology or data, but a lack of global diversity in the people being studied. The authors contend that the field has become overwhelmingly concentrated in wealthy, industrialised nations, limiting scientific discovery.
Led by Chilean bioinformatician Dr. Benjamin Valderrama and neuroscientist Professor John F. Cryan, both based at APC Microbiome Ireland, the international team of researchers argue that expanding microbiome-gut-brain research across Latin America, Africa, Asia and other underrepresented regions is not simply an issue of equity, it is essential if scientists are to uncover universal biological principles that can improve mental health worldwide.
"We often think about diversity in research as an ethical issue. Our argument is that it is also a scientific necessity. If we only study one part of the world, we risk misunderstanding how the microbiome shapes brain health,” said Dr. Benjamin Valderrama.
A new scientific frontier
The microbiome-gut-brain axis describes the constant communication between the microorganisms living in our intestines and the brain through immune, neural, endocrine and metabolic pathways. It has emerged as one of the most exciting areas of biomedical science, with implications for depression, anxiety, neurodevelopmental conditions, neurodegenerative disease and healthy ageing. Yet this publication argues that most of this knowledge comes from populations living in wealthy, highly urbanised, industrialised societies.
Because the microbiome is shaped by diet, environmental exposures, urbanisation, pollution, socioeconomic conditions and cultural practices, discoveries made in one part of the world may not always translate universally. Rather than representing background "noise", these differences may hold the key to understanding why mental health varies across populations and to identifying entirely new biological pathways.
Professor John F. Cryan added: "The remarkable progress we've made has largely come from studies in industrialised societies. The next breakthroughs will come from complementing that work with equally rigorous research across much more diverse populations."
Nature's own experiments
One of the publication’s central ideas is that many countries in the Global South offer unique opportunities to understand how environment shapes mental health. Rapid urbanisation, changing food systems, environmental transitions and socioeconomic gradients often exist within relatively small geographical regions, creating what the authors describe as ‘natural experiments’ that cannot easily be reproduced in laboratories. Studying these populations could help scientists disentangle the complex interactions between microbes, diet, environment and the brain in ways that are simply not possible when research is confined to wealthy countries.
Learning from the Global South
The perspective also challenges long-held assumptions about where innovation originates. Traditional diets rich in fibre, fermented foods and minimally processed ingredients, still common in many parts of Africa, Asia and Latin America, may contain important clues for protecting brain health. Instead of viewing lower-income countries solely as places where health problems occur, the authors argue that they should also be recognised as sources of scientific insight capable of informing future microbiome-based therapies and public health strategies worldwide.
Dr Valderrama said: "Many of the world's most informative microbiome studies have yet to be done. By studying populations experiencing different diets, environments and lifestyles, we may answer questions about the microbiome-gut-brain axis that simply cannot be answered in highly industrialised settings alone.”
A call for global collaboration
The authors stress that expanding microbiome research must be built upon equitable international partnerships. They call for greater investment in research infrastructure, leadership opportunities for researchers in low- and middle-income countries, equitable data sharing and long-term collaborations that benefit all partners. The ultimate goal, they argue, is not simply to make research more representative, but to build a stronger scientific foundation for the next generation of microbiome discoveries.
"The microbiome-gut-brain axis has fundamentally changed how we think about mental health over the past twenty years," Professor Cryan concluded. "The next twenty years will depend on thinking globally. The greatest discoveries may come not from studying more of the same populations, but from embracing the remarkable diversity of people, environments and cultures that shape the human microbiome."
The authors hope the article will encourage funders, policymakers and researchers to build more equitable international partnerships and to recognise that understanding the biology of mental health requires studying the full diversity of human populations.
About the study
The Perspective was led by Dr Benjamin Valderrama, a Chilean PhD student and bioinformatician based in APC Microbiome Ireland at University College Cork and brings together an international team of researchers from Brazil, South Africa, Kenya, the United Kingdom and Ireland. The collaboration reflects the paper's central message that understanding the microbiome-gut-brain axis requires genuinely global scientific partnerships.
