Many vaping products are designed to feel cool and refreshing when they are inhaled. This cooling sensation is one reason why some people find e-cigarettes appealing.
In recent years, manufacturers have increasingly used synthetic cooling ingredients instead of traditional flavors such as mint or fruit. These chemicals can create a cold feeling in the throat and mouth without adding a strong taste.
At the same time, scientists have been trying to understand whether these newer ingredients are truly harmless.
Although e-cigarettes are often marketed as alternatives to traditional cigarettes, they still contain nicotine and many other chemicals that can enter the body through the lungs. Researchers are discovering that some of these substances may affect the heart, blood vessels, and lungs in ways that are not yet fully understood.
A new study published in Circulation: Arrhythmia and Electrophysiology has raised fresh concerns.
The research, led by scientists at the University of Louisville School of Medicine, found that synthetic cooling ingredients commonly used in e-cigarettes triggered changes linked to abnormal heart rhythms in both mice and human heart cells grown in the laboratory.
The investigators focused on two popular cooling compounds called WS-3 and WS-23. These substances have become increasingly common because they make inhaling vapor feel smoother and reduce the harsh sensation sometimes caused by nicotine.
Because they do not have a strong flavor, they often fall outside rules that target flavored vaping products aimed at reducing youth appeal.
To explore whether these chemicals could influence heart health, the researchers conducted carefully controlled experiments. Male mice were exposed to aerosols from e-cigarettes containing nicotine and different cooling agents.
The scientists continuously measured heart rate, electrical activity, and the appearance of irregular heartbeats. They also collected blood samples to examine nicotine levels.
The team performed a second experiment using human heart cells that had been grown in the laboratory. These cells allowed the researchers to observe how cooling ingredients directly influenced heart tissue. The scientists also exposed the cells to a stress hormone that resembles the body’s response during excitement, anxiety, or nicotine stimulation.
The results suggested that cooling ingredients may make the heart’s electrical system less stable. All of the cooling agents altered heart rate variability, a measure that reflects how the heart responds to signals from the nervous system.
Changes in this measure are associated with increased cardiovascular stress and a greater chance of irregular heartbeats.
The chemical called WS-23 produced particularly strong effects. Mice exposed to e-cigarettes containing WS-23 experienced many more premature heartbeats than mice exposed to nicotine alone.
The animals also showed signs that the heart’s electrical system was preparing for the next heartbeat either too early or too late, changes that may raise the risk of dangerous arrhythmias.
The human heart cells showed another interesting pattern. Under normal conditions, the cooling chemicals did not dramatically alter heart activity. However, once the cells were exposed to stress-related hormones, the cooling agents changed the timing of electrical recovery between beats.
This finding suggests that the ingredients may be particularly problematic when the heart is under stress.
The researchers did not find clear evidence that the cooling agents increased nicotine absorption. Instead, the results suggest that the chemicals themselves may directly influence heart function.
The study has limitations. Animal studies cannot fully predict what happens in humans, and only male mice were examined.
The human heart cells used in the laboratory also cannot reproduce all the complicated interactions that occur inside a living person. Furthermore, commercial vaping products often contain many additional ingredients that were not included in this study.
Even with these limitations, the findings are important because they identify a previously underappreciated source of potential harm. Sales of products containing synthetic cooling agents have grown rapidly, yet very little has been known about their cardiovascular effects.
The study suggests that ingredients added mainly to improve the vaping experience may carry biological risks that deserve closer attention.
Overall, the research does not prove that synthetic cooling ingredients cause heart rhythm disorders in people who vape. Long-term studies in humans are still needed. However, the findings provide a strong reason for scientists, doctors, and regulators to investigate these additives further.
They also serve as a reminder that FDA authorization of certain vaping products does not mean they are risk-free. As researchers continue to study e-cigarettes, understanding the effects of every ingredient will be essential for protecting public health.
If you care about heart health, please read studies about how vitamin D influences cholesterol levels, and what we know about egg intake and heart disease.
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Source: University of Louisville.
