Inhaling the flavored liquid used in electronic cigarettes may increase your risk of heart disease, according to a new study from the Stanford University School of Medicine. Researchers found that cells exposed to the flavoring liquids exhibit significantly increased levels of DNA damage and cell death. “Until now,” said Dr. Joseph Wu, the study's senior author and the director of the Stanford Cardiovascular Institute, “we had no data about how these e-liquids affect human endothelial cells,” referring to cells that line blood and lymphatic vessels. “This study clearly shows that e-cigarettes are not a safe alternative to traditional cigarettes.” The Stanford team also found that the severity of the damage varied by flavor. Cinnamon and menthol were found to be particularly harmful, according to the researchers. The range of flavor options for e-cigarettes often attracts younger users. Experts say the flavors pose a risk of re-normalizing smoking and undoing years of progress in public health.