Polydextrose (PDX) is a synthetic low-calorie carbohydrate, a polysaccharide composed of D-glucose (dextrose) and sorbitol , which are derived from cornstarch, and citric or phosphoric acid. Polydextrose is commonly used as a replacement for sugar , starch , and fat in commercial beverages, cakes , candies , dessert mixes, breakfast cereals, gelatins , frozen desserts, puddings , and salad dressings . Polydextrose is frequently used as an ingredient in low-carb , sugar-free, and diabetic cooking recipes. It is also used as a humectant , stabiliser , and thickening agent .