A new study, led by researchers from the Stanford School of Medicine, has found e-cigarettes can damage human blood vessel cells and potentially increase the risk for cardiovascular disease. The study revealed some e-cigarette flavoring liquids are more damaging than others, regardless of nicotine concentrations.
The research focused on six different flavoring liquids, with varying levels of nicotine. The goal was to explore what effect these liquids had on human endothelial cells generated from induced pluripotent stem cells. Endothelial cells line the interior of our blood vessels and play a major role in maintaining good cardiovascular health.
"Until now, we had no data about how these e-liquids affect human endothelial cells," explains Joesph Wu, senior author on the new study. "When we exposed the cells to six different flavors of e-liquid with varying levels of nicotine, we saw significant damage. The cells were less viable in culture, and they began to exhibit multiple symptoms of dysfunction."
Six different flavoring liquids were investigated, across three different nicotine concentrations. Cytotoxicity varied notably from flavor to flavor but the cinnamon e-liquid significantly stood out as the most toxic product. Cellular migration and decreases in cell viability were prominent when endothelial cells were exposed to all the e-liquids, however, the damage was most significant with the cinnamon flavor, and importantly, damage was identified even in samples without nicotine.
Of course, it is important to note that these experiments were conducted on cells in laboratory conditions. Nevertheless, the researchers do suggest the association between endothelial cell dysfunction and exposure to these e-cigarette flavoring liquids reasonably affirm the liquids as potentially harmful, and the changes seen in the research do resemble what is seen in humans developing cardiovascular disease.
Another strand of the study examined nicotine levels in the blood of e-cigarette users compared to traditional cigarette smokers. Nicotine levels were tracked after 10 minutes of constant smoking and the researchers found both groups generated similar blood serum levels of nicotine. The concern this raises, says Wu, is that e-cigarette users can easily consume more nicotine in a single sitting due to the abstract nature of vaping, compared to smoking a single cigarette.
"When you're smoking a traditional cigarette, you have a sense of how many cigarettes you're smoking," says Wu. "But e-cigarettes can be deceptive. It's much easier to expose yourself to a much higher level of nicotine over a shorter time period."
Alongside this newly published Stanford research, the European Respiratory Society Tobacco Control Committee delivered a strongly worded statement suggesting e-cigarettes should not be widely recommended in smoking cessation strategies. The international coalition of respiratory doctors and scientists claims there is a lack of evidence as to whether e-cigarettes help stop people smoking for good, and these alternative nicotine delivery systems may be hooking a new generation on nicotine.
"Although exposure to potentially harmful ingredients from e-cigarettes and heated tobacco devices may be lower than cigarettes, this does not mean that they are harmless," says Tobias Welte, President of the European Respiratory Society. "Until we know more about the long-term effects of their use on human health, it is irresponsible to recommend that they be used in population-wide tobacco control strategies."
The new study was published in the Journal of the American College of Cardiology.
Source: Stanford Medicine