Nutritional yeast is a deactivated yeast that is commonly used in vegan and vegetarian cuisine. It is a good source of B vitamins, including B1, B2, B3, and B6. This ingredient has a cheesy, nutty flavor that can add depth and richness to dishes like popcorn, pasta, and sauces. It is also used in vegan cheese and vegan parmesan recipes. Some people use it as a substitute for cheese or as a seasoning. Overall, nutritional yeast is a versatile and healthy ingredient that can be used in many different ways.