Microplastics and gut health: First evidence of effects on human microbiome

The human gut microbiome plays a crucial role in digestion, nutrient production, and immune system regulation, yet its interactions with emerging environmental factors, such as microplastics, remain poorly understood. In this interview, Christian Pacher-Deutsch (Medical University of Graz and CBmed, Graz, Austria) explains how microplastics can alter gut bacterial composition and metabolism, the novel experimental approach of his study analysing interactions between real-world plastic particles and the human microbiome, and the potential implications of the findings for human health.

The abstract “‘Microplastics found to change gut microbiome in first human-sample study” was presented at UEG Week, 4–7 October, Berlin, Germany.

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My name is Christian Pacher-Deutsch. I’m a PhD student at the Medical University of Graz and CBmed, which is a biomarker company.

Why is the gut microbiome so central to human health, and what was the rationale for your study?

We live in close connection with our microbiome. The interplay already starts at birth, and it remains extremely important throughout our lives. It helps us to digest our food, and it produces essential nutrients and signalling molecules for us. It’s very closely connected to our immune system. A lot of these interactions are still little researched, and microplastics are a rather new factor coming into this complex system. Our aim basically was to uncover the influence that microplastics can have on this network.

How did you expose gut microbiome cultures to different microplastics, and what makes this approach novel?

Instead of using lab-produced microplastic particles, we implemented particles that resembled what we could actually ingest. This included particles produced from ground-up coffee cups or even PET bottles, but also spherical particles that are used in the cosmetics industry, for example in lipstick. The particles were then added to our bioreactors in an anaerobic way to keep the conditions for our cultures stable all the time.

What key microbiome or metabolic changes did you observe?

We were able to show that microplastics can influence the metabolism of bacteria. In our bioreactor experiments, several metabolites and bacterial taxa changed significantly in the presence of microplastics. The change in pH was rather uniform, reflected in overlapping outcomes in the impact of metabolites. On the other hand, changed bacterial taxa were diverse between plastic types, highlighting the complexity of microplastics. The impact on the microbiome is definitely given, but the overall health implications still need to be explored further, especially in combination with human host factors like the immune system.

How should healthcare professionals interpret the links to conditions like colorectal cancer or depression?

Well, plastics cannot be completely banned from daily life, but we must recognize its risks and take steps to protect people, just as we do with other environmental hazards. Health authorities should support biomonitoring and epidemiological studies to better understand exposure and defects. Evidence-based regulations and recommendations will only be possible with more data.

Given microplastics’ ubiquity, what do these findings mean for patients and clinicians today?

We know from a plastic fasting study that we conducted that avoiding plastics is basically impossible. We know microplastics have been found in different parts of the human body, but to which extent is still unclear. Before we can introduce targeted protective measures, we need to better understand the biological implications of microplastic exposure. That’s why research and biomonitoring are the most important steps right now.