Polyols are carbohydrate (sugar) derivatives, which formally are obtained by hydrogenation of the corresponding reducing sugars.
Polyols are also referred as sugar alcohols. Chemically Polyols are polyhydric alcohols. An Aldose sugar (a group of sugars bearing formally an aldehyde group when drawn in its open chain form), like e.g. D-Glucose is hydrogenated into its corresponding polyol D-Sorbitol, whereas a Ketose sugar (a group of sugars bearing formally a keto group when drawn in its open chain form), like e.g. D-Fructose is hydrogenated into equal amounts of D-Sorbitol and D-Mannitol.
There is an unequivocal relationship of the hydrogenation product of a sugar and the corresponding Polyol(s). The same Polyol, however, can be obtained from different starting sugars as is the case for Mannitol. Mannitol can be obtained by hydrogenation of its parent aldose sugar Mannose or from Fructose. Mannose yields Mannitol as the sole hydrogenation product, whereas Fructose yields equal amounts of Sorbitol and Mannitol.