WASHINGTON (AP) -- E-cigarettes aren't considered as risky as regular cigarettes, but new research finds a clue that their flavorings may be bad for the heart.
Longtime smokers sometimes switch to e-cigarettes in hopes of avoiding the cancer-causing chemicals in tobacco smoke. But cigarette smoking also is a leading cause of heart attacks.
There's little known about risks from chemicals inhaled in e-cigarettes' vapor, something especially important to learn as more teens take up vaping.
In a study published Monday, Stanford University researchers write about how they used lab dishes to grow cells that normally line healthy blood vessels. Exposing the cells to flavorings from e-cigarettes or blood from people who'd just vaped triggered blood vessel dysfunction that can increase the risk of heart disease.
This kind of small study can't prove harm; more research is needed.