Sweetened compositions comprising at least one sweetener and rebaudioside X are provided herein. Rebaudioside X is present in the sweetened compositions in a concentration at or below the sweetness recognition threshold, while the at least one sweetener is present in a concentration above its sweetness recognition threshold. Rebaudioside X acts to enhance the sweetness of the sweetened compositions, e.g. beverages and concentrate compositions, thereby allowing for preparation of sweetened compositions with reduced calorie content. Methods of enhancing the sweetness of a sweetened composition with rebaudioside X are also provided herein.