A four-carbon polyol that forms white crystals in pure form, occurring naturally in some animal and plant tissues, lichens and fermented foods. It has about 75% of the sweetness of sucrose, low hygroscopicity and a cooling effect. Used in sugar-free and low-sugar products, it is largely excreted unchanged and contributes almost no calories. Produced industrially by fermenting glucose with yeasts such as Moniliella pollinis, it is about 70% as sweet as sucrose with a pronounced cooling sensation from its negative heat of solution. It does not promote tooth decay, has a glycaemic index near zero, and is well tolerated — though very high intakes can cause digestive discomfort — making it popular in keto and diabetic products.