Embracing the Paleo lifestyle? Mannitol Powder is a plant-derived sweetener that tastes like sucrose but with a much lower glycemic index and it contains only 1.6 calories per gram. You likely know it best as the sweetener coating each raisin in your morning raisin bran cereal. It is a white, odourless, crystalline powder that used as a sweetener in sugar-free chewing gum and doesn't cause tooth decay.