The structure of diacetyl is similar to that of a substance that makes beta-amyloid proteins. When too much of this protein clumps together in the brain and forms plaque, it’s a surefire sign of Alzheimer’s. The scientists found that diacetyl leads to an increase of the clumping of these proteins, which has toxic effects on nerve cells. Not only that, but diacetyl also breaks down a barrier in the brain that keeps out hazardous materials.

Don’t hurry and toss your popcorn in the trash just yet. These results have only been shown in test tubes and haven’t been replicated in people yet. Before ya nosh, though, check the ingredients label on the back of your box o’ microwave popcorn. Even though some major brands have already removed diacetyl, there are other icky ingredients you might want to avoid.

Always a safe choice? Grabbing a jar of corn kernels at the grocery and popping them in oil in a heavy-bottomed pan on the stove, or in an air popper. Yum!