Also known as galactosyl-glucitol
Lactitol is a polyol that is produced by hydrogenation of lactose.
Lactitol is not efficiently absorbed by the body, and it is only partly metabolized. Its caloric value depends on several factors, as discussed in my essay "Polyols and Calories." In the USA, lactitol provides 2 calories per gram for labeling purposes. In the European Union, it is listed at 2.4 calories per gram.
Lactitol is not hygroscopic (does not absorb moisture from the air), so it is useful in products where crispness is desirable. It also performs well in chocolate. It has very good stability and solubility.
Lactitol has GRAS status in the USA. It is approved for use in the European Union (EU),
Canada, Japan, and several other countries.
The Joint FAO/WHO Expert Committee on Food Additives has determined the "Laxative Threshold Value" (LTV) for a number of polyols, and lactitol has an LTV of 24-50 grams per meal.