Microplastics and heart disease: Emerging evidence of a hidden cardiovascular threat

A recent study led by researchers at the University of California, Riverside, and published in Environment International suggests that everyday exposure to microplastics may directly contribute to the development of heart disease.

Using a mouse model naturally prone to atherosclerosis, the researchers found that environmentally realistic doses of microplastics dramatically accelerated the buildup of plaque in major arteries.

The effect was particularly pronounced in male mice, which developed significantly more arterial plaque than their unexposed counterparts, while female mice showed little to no increase. This indicates a possible sex-specific vulnerability.

Atherosclerosis is a condition in which the arteries become narrowed and hardened due to the buildup of plaque—a sticky mix of fat, cholesterol, calcium, and other substances—on the inner walls of blood vessels.

Restrict blood flow

Over time, plaque can restrict blood flow, reduce oxygen supply to organs and tissues, and increase the risk of serious cardiovascular problems such as heart attacks, strokes, and peripheral artery disease. In simple terms, atherosclerosis is often called "hardening of the arteries," and it usually develops gradually over many years.

What makes these findings particularly concerning is that microplastics caused these harmful changes without affecting traditional cardiovascular risk factors such as body weight or cholesterol levels.

This suggests that microplastics may harm the cardiovascular system through a direct biological mechanism rather than through conventional metabolic pathways.

Further analysis revealed that endothelial cells—the cells lining blood vessels—were especially affected, with gene activity shifting toward inflammation and plaque formation. This points to a direct irritation or injury of blood vessel walls by microplastic particles.

Additional concerns

The study also found microplastics embedded within developing arterial plaques, confirming observations from previous human studies. Their physical presence in vascular tissue raises additional concerns about the potential depth and severity of biological disruption caused by these particles.

The researchers warn that because microplastics are pervasive in food, water, and even the air we breathe, these findings have important implications for human health.

While further research is needed to understand why males appear more susceptible and how different types or sizes of microplastics affect the body, the study provides some of the strongest evidence to date that everyday exposure to microplastics could be an overlooked contributor to cardiovascular disease.

Based on the study, male mice were more affected by microplastic exposure, developing significantly more arterial plaque than female mice. While the exact reason is not fully understood, researchers suggest that the difference is likely due to a combination of hormonal and genetic factors.

"Oestrogen, the primary female sex hormone, has protective effects on blood vessels: it helps maintain healthy endothelial function, reduces inflammation, and can slow the buildup of arterial plaque," the researchers noted.

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Male mice, lacking this protective effect, may therefore be more susceptible to damage from microplastics.

Triggered inflammation

Genetic differences related to sex chromosomes may also play a role, influencing how endothelial cells respond to stress or toxins. Additionally, the study indicated that microplastics triggered inflammation in the cells lining blood vessels, and males may experience a stronger or more damaging inflammatory response, which accelerates atherosclerosis compared to females.

In essence, male biology may make them more vulnerable to the artery-damaging effects of microplastics, though further studies are needed to fully clarify the mechanisms.

Microplastics are dangerous to humans because they can enter the body through food, water, and even the air we breathe, and once inside, they have the potential to harm health in multiple ways.

These tiny plastic particles can irritate cells and tissues, triggering chronic inflammation linked to diseases such as heart disease, diabetes, and certain cancers. They can also interfere with normal cell function, particularly in the lining of blood vessels, the gut, and the lungs, leading to tissue damage or impaired organ performance.

Harmful chemicals

In addition, microplastics often carry harmful chemicals, such as phthalates and bisphenol A (BPA), which can leach into the body and disrupt hormones or metabolism, potentially increasing the risk of chronic illnesses.

They can also act as carriers for bacteria and other harmful microorganisms, introducing pathogens into the body. Because microplastics are non-biodegradable, they can accumulate over time in organs and tissues, including the gut, liver, kidneys, lungs, and even the bloodstream.

Microplastics are concerning because they are pervasive, persistent, and capable of causing inflammation, cellular damage, and chemical disruption, all of which can have serious implications for human health.

Adding to the growing research on microplastics, a study in Italy examined artery plaques removed from over 250 patients and found tiny plastic particles—mostly polyethene and some polyvinyl chloride—embedded in more than half of the samples.

Significantly higher risk

Patients whose plaques contained microplastics faced a significantly higher risk of cardiovascular events. Over a three-year follow-up, these individuals were about 4.5 times more likely to experience a heart attack, stroke, or death compared to those without plastic in their arteries. The affected plaques also showed increased signs of inflammation, suggesting that microplastics may actively contribute to vascular damage and the progression of cardiovascular disease.

Similarly, another study focused on patients with acute coronary syndrome, including those who had suffered heart attacks. Researchers measured microplastic levels in the blood and found that patients with higher microplastic burdens also exhibited elevated markers of immune activation and inflammation, such as IL‑6 and IL‑12, as well as increased counts of B lymphocytes and natural killer cells.

These findings indicate that microplastics in the bloodstream may trigger harmful immune and inflammatory responses, potentially promoting vascular injury and worsening heart disease.

Not just environmental contaminants

Together, these studies strengthen the evidence that microplastics are not just environmental contaminants but may also play a direct role in human cardiovascular disease, supporting concerns raised by recent experimental research in animal models.

Cardiovascular disease (CVD) is a leading cause of death both globally and in Kenya. Worldwide, an estimated 19.8 million people died from cardiovascular diseases in 2022, accounting for roughly 32 per cent of all deaths. Of these deaths, about 85 per cent were due to heart attacks and strokes. The burden of cardiovascular disease is disproportionately high in low- and middle-income countries, which account for more than three-quarters of all CVD deaths.

In Kenya, cardiovascular disease contributes to approximately 13.8 per cent of all deaths. Stroke alone accounts for around 6.1 per cent of total deaths, while ischemic heart disease, or heart attacks, represents about 4.6 per cent. In 2024, Kenyan health facilities recorded 7,478 deaths directly attributed to cardiovascular diseases.