Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was reviewed?
This scoping review synthesized the existing literature published between 2010 and 2025 on the impact of various air pollutants, including heavy metals, on the human gut microbiota and the subsequent health consequences. The review aimed to map the evidence connecting air pollution exposure to microbial dysbiosis and to elucidate the biological pathways, such as the gut-lung and gut-brain axes, through which these effects are mediated. The analysis encompassed a wide range of pollutants, with a specific focus on the role of heavy metals in disrupting gut microbial homeostasis and contributing to systemic inflammation and disease.
Who was reviewed?
The review analyzed 158 studies, which included 82 original research articles, 68 review papers, and other publication types like book chapters and conference papers. The research subjects from the original studies spanned human populations across various age groups and geographic regions, animal models such as mice, rats, and Drosophila, and in vitro analyses. A significant geographic bias was noted, with a predominance of studies from China and the United States, while research from low- and middle-income countries, where heavy metal exposure is often higher, was limited.
Most important findings
| Finding Category | Specific Details Relevant to Heavy Metals |
|---|---|
| Microbial Shifts | Exposure to heavy metals reduces alpha-diversity and alters taxonomic composition, such as decreasing beneficial bacteria like Bifidobacterium and increasing pro-inflammatory phyla like Proteobacteria. |
| Health Consequences | Heavy metal-induced dysbiosis is linked to intestinal barrier damage (“leaky gut”), systemic inflammation, insulin resistance, neurological impairments (e.g., cognitive decline), and exacerbation of conditions like IBD. |
| Mechanisms | Heavy metals disrupt gut health by activating inflammatory pathways (e.g., TLR4-NF-κB), reducing production of beneficial short-chain fatty acids (SCFAs), and increasing oxidative stress. |
| Detoxification & Mitigation | Specific probiotic strains, such as Bacillus megaterium (Renuspore®), demonstrated an ability to detoxify heavy metals, degrade other pollutants, and produce beneficial SCFAs, thereby restoring microbial balance. |
| Vulnerable Populations | Infants and children are particularly vulnerable to heavy metal exposure, which can lead to long-lasting alterations in gut microbiota composition and an increased risk of metabolic and neurodevelopmental disorders. |
Key implications
The primary regulatory impact is the need to recognize gut dysbiosis as a biomarker for heavy metal exposure, informing stricter air quality standards. Certification requirements should validate products that mitigate heavy metal bioavailability or support gut resilience, such as specific probiotics. Industry applications include developing microbiome-supportive supplements and functional foods for at-risk populations. Critical research gaps involve long-term human studies and the effects of heavy metal mixtures. Practical recommendations include integrating gut health protection into public health advisories for polluted areas.
Citation
Thomas T, Nashwan AJ. Air Pollution and Disrupted Microbiomes: Tracing the Impact on Human Health. Cureus. 2025;17(8):e89267. DOI: 10.7759/cureus.89267
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
