Two new studies will be presented at the American Heart Association’s Scientific Sessions, giving insight into possible cardiovascular effects of vaping, including the risk of e-cigarette heart disease.

Though vaping is often advertised as a smoking cessation tool, MarketWatch reports it is not FDA approved for this purpose. Among its documented negative effects, people who use e-cigarettes tended to have a higher rate of bad cholesterol than those who don’t smoke at all, according to one of the studies presented.

The author of one study, Sana Majid, a postdoctoral fellow in vascular biology at the Boston University School of Medicine, says that “the best option is to use the FDA-approved methods to aid in smoking cessation, along with behavioral counseling.” 

Experts worry that multiple elements of e-cigarettes could be dangerous to human health, but research is still emerging about the causes behind the possible dangers of vaping. Reportedly, the Centers for Disease Control and Prevention explained that vitamin E acetate, a chemical in vaping fluid may be linked to e-cigarette lung injury.

Earlier this year, a study from Stanford Medicine and published in the Journal of the American College of Cardiology indicated that the flavored vaping liquid could also be linked to e-cigarette heart disease — not just lung injury. Stanford Medicine explains that endothelial cells are the cells on the cells lining the inside of blood vessels. Reportedly, endothelial cells that have been exposed to e-liquid were subjected to damage and malfunctioned in multiple ways.

The Stanford study reported that the exposed endothelial cells had more molecules related to DNA damage and cell death, and were impaired in their function to help heal wounds, form vascular tubes, and to migrate.

Reportedly, different flavors of e-liquid affected endothelial cells to varying degrees. Researchers found that cinnamon and menthol-flavored e-liquids posed the most danger to the viability of endothelial cells.

In an effort to curb the attraction of e-cigarettes to young people, the FDA is in the process of attempting to restrict the sale of flavored e-cigarette liquid, other than menthol and tobacco flavored, says the Wall Street Journal. However, a significant danger could still be posed by menthol-flavored e-liquid, if menthol is among the most dangerous flavors, as the Stanford study suggests.

Nicotine itself may also be linked to e-cigarette heart disease, given its possible effects on the cardiovascular system. The American Heart Association says that nicotine can increases blood pressure, heart rate, and the flow of blood to the heart. Additionally, nicotine can narrow the arteries and can harden the arteries. The combination of these elements may lead to a heart attack.

Though e-cigarettes are often sold as a smoking cessation tool, they can contain more nicotine than traditional cigarettes. Part of the risk associated with vaping is that the user may not know how much nicotine they are ingesting with the use of an e-cigarette.

Senior author of the Stanford study summarized the e-cigarette heart disease risk linked to nicotine, saying that when a person uses an e-cigarette, “it’s much easier to expose yourself to a much higher level nicotine over a shorter time period.” He goes on to say that in general, the new research indicates that “e-cigarettes are likely to have other significantly toxic effects on vascular function as well.”