Scientists are still trying to determine the health effects of e-cigarettes, and until now, they have focused their attention on the addictive properties of nicotine and the potentially cancer-causing agents in the vapors the devices emit.
But in a small new study published in the Journal of the American Heart Association, researchers document another growing health concern of e-cigs: that they may have negative effects on the heart. Scientists led by Dr. Holly Middlekauff, professor of medicine at University of California Los Angeles, and her colleagues found that devices that contain nicotine can boost adrenaline levels in the heart—essentially putting the heart under stress, which is a major risk factor for heart attack and stroke.
Middlekauff studied 33 healthy people who were not current tobacco or e-cigarette smokers and asked them to come to the lab on three different days. At each visit, they smoked a different device: a placebo with no active ingredients, an e-cig with nicotine or an e-cig without nicotine. (While e-cigs do not burn tobacco, most do contain nicotine.) For years, doctors believed that nicotine, while addictive, was not the component in cigarettes that posed the biggest health risk. Instead, they thought the tar that was more concerning. By comparing nicotine and non-nicotine e-cigs, Middlekauff wanted to determine whether the same was true for nicotine and the heart.
She found that only the nicotine e-cigs caused an increase in adrenaline levels, which raises new concerns about the dangers of nicotine. While doctors have been worried about the non-nicotine components of e-cigs because of their link to cancer, nicotine may also be contributing to heart problems. That’s especially worrisome if people are turning to e-cigarettes as replacements for tobacco cigarettes. “Long-term inhaled nicotine hasn’t been studied in terms of heart risk,” says Middlekauff. “If it leads to high adrenaline levels in the heart, which has been shown to be a risk factor in people both with and without heart disease, then that’s a problem.”
Based on the current results and her previous work, Middlekauff suggests that non-smokers should not start using e-cigarettes because they think they are a safer alternative to tobacco cigarettes. But for current smokers of tobacco cigarettes, the e-cigs might be a slightly better option. (Many smokers rely on e-cigs as a way to wean themselves off from smoking.) Her earlier imaging studies that looked at inflammation in the body due to smoking found slightly less inflammatory responses to e-cigs than to tobacco cigarettes, she says. Inflammation, which can disrupt unstable plaques in the blood vessels, can contribute to heart attack and heart disease.
“The way I think about it is that if you currently smoke tobacco cigarettes, switching to e-cigs may be a better choice, at least from the data we have,” she says. “But if you don’t smoke at all, I would strongly advise that you not start using e-cigarettes, because they are not harmless.”