Electronic cigarettes may be the lesser of two evils, but they may also be capable of doing their own damage – through the nicotine they contain.

The safety of nicotine is widely controversial, and possibly not fully understood or researched – with advocates of e-cigarettes arguing that nicotine is safe, and others claiming that it’s actually quite harmful. A new study out of Brown University states that nicotine in particular, rather than other chemicals found in regular cigarettes, may damage arteries. And though e-cigarettes don’t contain as many carcinogens or chemicals as tobacco smoke does, they do maintain levels of nicotine, aimed for helping people quit traditional cigarettes.

A physiologist at Brown University, Chi-Ming Hai, announced these results at the American Society for Cell Biology (ASCB) annual meeting. The study was focused on vascular smooth muscle cells, which can be affected by nicotine, he says. Normally, vascular muscle cells place themselves around blood vessels to help keep blood flow and blood pressure under control. Inflammation, chemicals, and nicotine, however, can cause these cells to transform into drills that chew through tissue. These cells then push into the arteries and end up accumulating into plaque, blocking blood flow, and creating an “atherosclerotic” artery.

“In my opinion, if taking nicotine for a short time can lead to complete cessation of smoking, e-cigarette included, then it will be beneficial to take nicotine for a short time as a bridge to smoking cessation,” Hai told Healthline. “However, our data suggest that long-term consumption of nicotine by e-cigarette smoking is likely to increase the risk of developing atherosclerosis by stimulating invasion of vascular smooth muscles cells.”

Nicotine’s Effect On Heart Disease?

Others, advocates of tobacco alternatives in particular, believe that nicotine's adverse health effects are so low that it doesn't matter. Researchers found in 2012 that nicotine replacement therapy (NRT) was not linked to any cardiovascular risks. Likewise, another study showed that Swedes who chewed tobacco did not have an increased risk of heart attacks compared to people who did not chew tobacco.

Carl Phillips, Scientific Director of the Consumer Advocates for Smoke-free Alternatives Association (CASAA), in particular has voiced his argument that Hai’s study should not deter people from using e-cigarettes as a reliable way to quit smoking. “What Hai discovered is that … cigarette smoke, smoke without nicotine, and nicotine alone all caused vascular tissue damage,” Phillips writes on his “Anti-THR” (tobacco harm reduction) blog. “[There is no] reason to believe that nicotine use, ex smoking, causes heart disease to any consequential degree.” Phillip claims that nicotine does not cause a “measurable” heart disease risk; he notes that Hai’s study is a toxicological one – it’s been done in a lab – rather than an epidemiological one, completed in the real world and in humans. Cardiovascular disease has indeed been linked to nicotine and tobacco smoke in the past, but Phillips says the risk is “too low to measure.”

Scientists have mostly believed in the past that it’s the other chemicals in smoke, not nicotine, that are the cause of adverse health effects. Because of this, many have assumed that e-cigarettes are safer than regular cigarettes. Though they are to a significant extent, consumers should also be aware that research regarding e-cigarettes is still preliminary.

Further research will need to be completed before e-cigarettes can be either labeled “harmful” or “safe.” Overall, nicotine replacement therapy such as nicotine patches, nicotine gum or lozenges, has been considered a safe substitute for smoking tobacco, which contains hundreds to thousands of carcinogens in just one cigarette. “We’re really at the beginning stages of understanding what the potential health impact [of e-cigarettes] might be,” Dorothy Hatsukami, a psychiatry professor at the University of Minnesota who is recruiting volunteers to study e-cigarette effects, told Healthline. “There could be public health benefits, certainly they are less toxic than cigarettes, but they may lead to other public health harms.”