Microplastics and human health: unveiling the gut microbiome disruption and chronic disease risks

Abstract

Microplastics (MPs), defined as plastic particles smaller than 5 mm, are increasingly recognized as environmental contaminants with potential health risks. These emerge as breakdown products of larger plastics and are omnipresent in marine, freshwater, and terrestrial ecosystems. They are primarily composed of polymers such as polyethylene, polypropylene, polystyrene, and additives that enhance their performance. MPs also adsorb harmful environmental chemicals like persistent organic pollutants and heavy metals, posing risks to human and environmental health. Human exposure to MPs occurs mainly through ingestion and inhalation, with MPs detected in food products, water, and even the air. MPs have been shown to accumulate in the gastrointestinal tract, disrupting the gut microbiome, and causing dysbiosis-a harmful imbalance between beneficial and harmful bacteria. This disruption has been linked to various health issues, including gastrointestinal disorders, systemic inflammation, and chronic diseases. Furthermore, the gut-brain axis may be affected, with potential neuroinflammatory consequences. As research continues to unravel the health impacts of MP exposure, understanding the mechanisms of accumulation and the broader implications on human health is crucial. This review highlights the effects of MPs on human health, emphasizing their impact on the gut microbiome. We discuss the potential connections between MP exposure and cardiometabolic and inflammatory diseases, and disorders related to the Gut-Brain Axis. By synthesizing the latest research, this work sheds light on the silent yet pervasive threat posed by MPs and underscores the importance of further studies to understand their health impacts fully.

Keywords: chronic diseases; dysbiosis; gut microbiota; human health; inflammation; microplastic.

Figure 1

Representative schematic showing the annual intake of microplastics (MPs) by humans through various routes, categorized into breathing (airborne exposure) and eating/drinking (dietary exposure). It gives a comprehensive overview of how different environmental sources contribute to the ingestion or inhalation of MPs yearly (Yang et al., 2023). It shows the pervasive presence of MPs in the environment and their inevitable incorporation into human life through daily activities.

Figure 2

Pathways of microplastic (MP) exposure and its impact on human gut microbiota. The figure illustrates the sources of plastic waste and their transformation into MPs which enter the human body through ingestion, inhalation, and dermal absorption. It also depicts the possible impacts of MPs on gut microbiota, including reduced microbial diversity, increased pathogenic bacteria, altered mucus secretion, metabolic changes, impaired intestinal barrier function, and increased inflammation (Covello et al., 2024; Demarquoy, 2024).

Figure 3

The complex interactions between microplastics (MPs) and the human gut, emphasizing the inflammatory response, alterations in gut microbiota, and potential downstream effects on health through oxidative stress and tissue damage. (A) Microplastic exposure (the entry of MPs into the human body); (B) MP-induced inflammatory response in the gut focusing on the gut’s immune response to MP-exposure. It shows how dendritic cells and macrophages recognize MPs and release pro-inflammatory cytokines (like TNF-α and IL-6). The presence of these cytokines leads to increased oxidative stress, and disrupts the intestinal barrier function. Healthy Paneth cells are involved in maintaining gut health, but MP-exposure can impair their function. (C) Pathways of oxidative stress and damage outlining the cellular pathways activated by MP-induced inflammation (Bahadur et al., 2023; Wallaeys et al., 2023; Sofield et al., 2024).