Study finds flavors in e-cigs can damage cells that are critical for a healthy heart; cinnamon and menthol flavors were the most toxic

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Flavors used in electronic cigarettes damage the cells that line the inside walls of blood vessels, which ultimately increases the risk of heart disease, a study has concluded.

The study, published in the Journal of the American College of Cardiology, exposed lab-grown endothelial cells, which normally line healthy blood vessels, to six different flavored e-liquids with varying nicotine concentrations.

The researchers found that following exposure, the cells were more likely to die early, showed increased levels of DNA damage, were less able to help form new blood vessels and were less able to participate in wound healing, Dennis Thompson reports for HealthDay News.

The study found that the cinnamon and menthol liquids were the most damaging to the cells, while the caramel and vanilla flavors were also damaging, but not as severely.

Senior researcher Dr. Joseph Wu told Thompson that if this same effect occurs in the human body, it could potentially increase the long-term risk of heart disease and stroke. Wu is director of the Stanford Cardiovascular Institute in California.

"If you're a chronic e-cigarette [user], you're probably going to be prone to more vascular disease in the future," Wu told Thompson. "It doesn't have the carcinogens associated with smoking, but don't use e-cigarettes with the assumption that if I switch to e-cigarettes it will be good for my cardiovascular health."

Wu added that endothelial cells, which line the heart and blood vessels, are critical to heart health and need to remain flexible to help manage blood pressure. Further, he said that when they are damaged they attract more cholesterol plaques and contribute to narrowing of the arteries, and stroke.

"The remarkable thing was there were very strong effects, both in terms of the specific mechanisms they looked at and that the effects were not very different between cells from e-cigarette smokers and cigarette smokers," Dr. Rose Marie Robertson,deputy chief medical officer of the American Heart Association, told Thompson.

Robertson also warned that the e-cigarette companies are using flavorings that have been approved by the U.S. Food and Drug Administration for ingestion, but not necessarily for inhalation.

Much of the concern about e-cigarettes is centered around the growing use of these products by teens, largely because they are attracted to the flavors.

"There's so many kids who are smoking e-cigarettes. And these kids are going to become adults. And these adults can become elderly patients that I as a cardiologist will take care of later on, " Wu told Michael Nedelman of CNN.

According to the Kentucky Incentives for Prevention survey, teen use of e-cigarettes in the state nearly doubled from 2016 to 2018. It found that 26.7% of high-school seniors reported using e-cigs in the month before they were surveyed, up from 12.2% in 2016. Among 10th graders, it increased to 23.2% from 11.3%; eighth graders to 14.2% from 7.3%; and sixth-graders to 4.2% from 2.3%.

A national study found that vaping increased nearly 80% among high schoolers and 50% among middle schoolers from 2017 to 2018.

Wu told Thompson that the researchers suspect that different components of e-cigarette vapor might harm blood vessel cells in different ways.

Environmental Health News calls this study the latest linking e-cigarettes to heart problems and points to two other bodies of research that link e-cig use and heart disease.

In March, it reported that researchers presented a study of nearly 100,000 Americans that found e-cigarette users are more likely to suffer heart attacks and strokes compared to non-users. In January, it reported on a big national study of 400,000 Americans that found e-cigarette users have a 70% higher risk of stroke and a 60% higher risk of heart attack, compared to non-users.