The flavorant, diacetyl, that a adds buttery taste to foods and a smooth feel to beverages may also trigger Alzheimer’s disease, new studies suggest. The flavorant already is linked to lung damage in people who work in microwave popcorn factories. This led many microwave popcorn makers to stop using diacetyl in their products. But now other workers exposed to diacetyl - and possibly consumers as well - face this new risk.