A rare sugar is a

sugar Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose Glucose is a sugar with the Chemical formula#Molecular formula, molecul ...

that occurs in limited quantities in nature. Rare sugars can be made using enzymes, choosing which enzymes to use if you know the substrate can be aided by the Izumoring-strategy. Specific examples of rare sugars are: * Allulose * Allose * Sorbose * Tagatose

References

Carbohydrates {{Carbohydrate-stub