Doctors from the University of Massachusetts Medical School conducted a study and proved that the flavors in vapes are harmful to the cells in the vessels of the heart. As it turns out, the flavors cause inflammation and even the death of certain heart cells. 6 flavors were tested and the most dangerous one was the cinnamon-flavored liquid.By the way, last year, experts also found a link between vapes and a higher risk of having a heart attack.