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, transforming our understanding of stress, depression, anxiety and neurodevelopment. A new international perspective published in Nature Mental Health, led by researchers at APC Microbiome Ireland in University College Cork, 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, industrialized 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 argues 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.

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, with implications for depression, anxiety, neurodevelopmental conditions, neurodegenerative disease and healthy aging. Yet most of this knowledge comes from populations living in wealthy, highly urbanized, industrialized societies. Because the microbiome is shaped by diet, environmental exposures, urbanization, pollution, socioeconomic conditions and cultural practices, discoveries made in one part of the world may not always translate universally — and these differences may hold the key to understanding why mental health varies across populations.

“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,” said Professor John F. Cryan.

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 urbanization, 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. 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.

“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,” Valderrama said.

The authors stress that expanding microbiome research must be built on equitable international partnerships, calling 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 microbiome-gut-brain axis has fundamentally changed how we think about mental health over the past twenty years,” Cryan said. “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 Perspective brings together an international team of researchers from Brazil, South Africa, Kenya, the United Kingdom and Ireland, reflecting its central message that understanding the microbiome-gut-brain axis requires genuinely global scientific partnerships.

Journal: Nature Mental Health
DOI: 10.1038/s44220-026-00690-w
Article Title: Global mental health benefits from expanding microbiome–gut–brain axis research to the global south
Publication Date: 20-Jul-2026

Source: EurekAlert