Quest Nutrition, which uses allulose in some of its protein bars, was the first major adopter. (Quest on Thursday announced it is being acquired by the parent of the Atkins brand for $1 billion.) Know Better baked goods and IQ Bar, also health-focused food companies, use it in their products. Coca-Cola has quietly tested it in the sweetener blend in a few flavors of its Fuze antioxidant teas.