Air Pollution Effects on Oral-Gut-Brain Health Connections

Introduction to Air Pollution and Its Health Risks

Air pollution is a critical global health issue with far-reaching implications for human health and well-being. According to a report by the Lancet, air pollution is responsible for millions of deaths annually, with significant contributions to various chronic diseases, including cardiovascular, respiratory, and neurological disorders (Chen et al., 2025). The health risks associated with air pollution are particularly concerning for vulnerable populations, including children, the elderly, and those with pre-existing health conditions. The complexity of air pollution’s effects lies in its ability to influence multiple organ systems simultaneously, exacerbating existing health problems and leading to new conditions.

The bidirectional regulatory network known as the oral-gut-brain axis connects the oral cavity, intestine, and central nervous system. This network plays a vital role in maintaining homeostasis and is influenced by various environmental factors, including air pollution (Chen et al., 2025). Disruptions in this axis can lead to systemic health issues, with emerging evidence suggesting that air pollution can significantly affect oral, gastrointestinal, and neurological health.

The Role of the Oral-Gut-Brain Axis in Health

The oral-gut-brain axis is a complex communication network that regulates various physiological processes. This axis involves intricate interactions between the oral cavity, gastrointestinal tract, and the central nervous system, mediated by hormonal, neuronal, and immune pathways. The health of the oral microbiome and gut microbiota is crucial for regulating immune responses, metabolism, and overall health (Chen et al., 2025).

Recent studies have indicated that disturbances in the oral-gut-brain axis may contribute to the development of various chronic conditions, including obesity, diabetes, and neurodegenerative disorders. For instance, alterations in gut microbiota composition have been linked to inflammatory responses that can affect brain health, leading to cognitive decline and conditions such as Alzheimer’s disease (Chen et al., 2025). Therefore, understanding the mechanisms that govern this axis is essential for developing effective interventions aimed at mitigating the health impacts of air pollution.

Impact of Air Pollutants on Oral Health and Microbiota

Air pollutants, including particulate matter (PM), nitrogen dioxide (NO2), and volatile organic compounds (VOCs), can have detrimental effects on oral health and the microbiome. Research has shown that exposure to PM can lead to an increase in oral inflammation, periodontal disease, and other oral health issues (Chen et al., 2025). The oral cavity serves as a gateway for pollutants, allowing them to enter the bloodstream and potentially affect systemic health.

Table 1 summarizes the effects of various air pollutants on oral health:

Studies indicate that specific bacteria associated with periodontal disease may proliferate in response to air pollution, potentially leading to systemic inflammation and contributing to the pathogenesis of diseases like heart disease and diabetes (Chen et al., 2025).

Mechanisms of Air Pollution-Induced Gut Dysfunction

Airborne pollutants can enter the gastrointestinal tract through various routes, including ingestion and inhalation. Once in the gut, these pollutants can disrupt the delicate balance of gut microbiota, leading to increased intestinal permeability, inflammation, and altered nutrient absorption (Chen et al., 2025). The inflammatory response triggered by air pollutants can contribute to conditions such as inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS).

The mechanisms underlying these effects include:

• Oxidative Stress: Exposure to air pollutants generates reactive oxygen species (ROS), leading to cellular damage and inflammation in the gut. This oxidative stress can weaken the gut barrier, allowing toxins to enter the bloodstream and trigger systemic inflammation.
• Microbiota Dysbiosis: Air pollution has been shown to alter the composition of gut microbiota, favoring pathogenic bacteria over beneficial strains. This dysbiosis can exacerbate gut inflammation and contribute to metabolic disorders.
• Immune Response: Pollutants can activate the immune system, resulting in chronic inflammation that may affect gut health and overall well-being.

Neuroinflammation and Cognitive Impairment from Air Pollution

The effects of air pollution extend beyond the gut and can significantly impact brain health. Exposure to air pollutants has been linked to neuroinflammation, cognitive decline, and the development of neurodegenerative diseases such as Alzheimer’s and Parkinson’s (Chen et al., 2025). Inhaled pollutants can reach the brain through the olfactory bulb or enter the bloodstream and cross the blood-brain barrier, leading to inflammation and neuronal damage.

Research has demonstrated that particulate matter can activate microglia, the brain’s resident immune cells, resulting in an inflammatory response that may contribute to neurodegeneration. Increased levels of pro-inflammatory cytokines, such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), have been observed in individuals exposed to high levels of air pollution, further supporting the link between air quality and brain health (Chen et al., 2025).

Strategies for Mitigating Air Pollution Effects on Health

To address the adverse health effects of air pollution, several strategies can be implemented at both the individual and community levels:

1. Awareness and Education: Increasing public awareness about the health risks associated with air pollution and promoting protective behaviors, such as wearing masks and using air purifiers, can help mitigate exposure.

2. Policy and Regulation: Governments should enforce stricter regulations on emissions from vehicles and industrial sources to improve air quality. Implementing policies to reduce reliance on fossil fuels and promote clean energy can contribute to long-term improvements in air quality.

3. Healthcare Integration: Healthcare providers should be trained to recognize the health effects of air pollution and incorporate environmental health assessments into patient care. This includes screening for respiratory and cardiovascular diseases in populations exposed to high pollution levels.

4. Research and Innovation: Continued research is essential to understand the mechanisms by which air pollution affects health and to develop targeted interventions. Innovations in air quality monitoring and pollution reduction technologies can also play a crucial role in protecting public health.

FAQ

What are the main health effects of air pollution?

Air pollution is linked to various health issues, including respiratory diseases, cardiovascular diseases, and neurodegenerative disorders. It can exacerbate existing conditions and lead to increased mortality rates.

How does air pollution affect the oral-gut-brain axis?

Air pollution can disrupt the balance of microorganisms in the oral cavity and gut, leading to inflammation and affecting brain health. This disruption can result in chronic diseases and cognitive decline.

What measures can be taken to reduce exposure to air pollution?

Individuals can reduce their exposure by using air purifiers, wearing masks in polluted areas, and avoiding outdoor activities during high pollution days. Governments can implement stricter emissions regulations and promote clean energy sources.

Is there a link between air pollution and neurodegenerative diseases?

Yes, research has shown that exposure to air pollution is associated with an increased risk of neurodegenerative diseases, such as Alzheimer’s and Parkinson’s. Pollutants can induce neuroinflammation and cognitive impairment.

What role does the microbiome play in health?

The microbiome is crucial for maintaining health by regulating immune responses, metabolizing nutrients, and preventing pathogen colonization. Disruptions in the microbiome can lead to various health issues, including inflammatory diseases and metabolic disorders.

References

1. Chen, S., Yu, W., Shen, Y., Lu, L., Meng, X. (2025). Unraveling the mechanisms underlying air pollution-induced dysfunction of the oral–gut–brain axis: implications for human health and well-being. Asian Biomedicine: Research, Reviews and News. DOI: 10.2478/abm-2025-0002

2. Link to the article