From heat-related illnesses to the geographic expansion of infectious diseases, the effects of climate change on human health are complex. And indeed, dimensions of this interaction, such as the impact of climate change on gut health, remain overlooked. 

Emerging research shows this global phenomenon may make you sick to your stomach — literally.  

Author Elena Litchman, an ecologist and a Michigan State University Research Foundation Professor, calls for interdisciplinary collaborations to solve this complex problem. A new review article appearing in The Lancet Planetary Health outlines how the compounding effects of climate change could weaken human gut microbiomes, with the most severe impacts expected across middle- and low-income countries. 

These regions face enhanced risks due to food insecurity, malnutrition and exposure to disease-causing pathogens. These challenges could have a cascading effect on the composition of gut microbial ecosystems worldwide. 

Heat stress can induce complex changes in the gut, including shifts in microbiota composition, increased oxygen levels and overproduction of stress hormones — changes that could make people more susceptible to harmful organisms. 

These changes could alter health at the molecular level, including disruptions to important digestive and immune functions. One consequence, Litchman says, is a diminished ability of the body to absorb vital nutrients: a problem made exponentially worse when nutritious food is in short supply. 

Additionally, the body’s gastrointestinal lining becomes more permeable under heat stress, allowing toxins and pathogens in the digestive tract to more readily enter the bloodstream. 

In middle- and low-income countries, especially those along the tropics, a surge in gastrointestinal diseases presents a multifaceted threat. Environmental changes promote the growth and spread of pathogens, while heat stress and food insecurity reduce the efficacy of humans’ natural immune functions. These countries are also less equipped to adapt to food shortages than high-income countries, resulting in a disproportionate impact in countries already inequitably affected by heat stress, illness and food insecurity.  

Examining how the availability and nutritional quality of food in at-risk areas affects the composition of the gut microbiome is a crucial first step toward mitigating worsened health outcomes, Litchman says.  

Rather than trying to solve the emerging health problems one by one, Litchman advises an approach that incorporates more interdisciplinary collaborations to look for solutions through a cross-disciplinary lens. She points to the World Health Organization’s One Health Initiative as a model for projects with potential to overcome disciplinary barriers.  

Without concerted, interdisciplinary efforts to mitigate risk among vulnerable populations, these compounding effects could place hundreds of millions of people at risk of illness and poor health outcomes.