Digestion and Absorption of Monosaccharides

[Amy L. Marion]

I am teaching a nutrition course and am looking for information about 
a plant-derived dietary supplement.  The manufacturer claims that 
this combination of monosaccharides is crucial to cellular 
communication since these are the most common sugar components of 
glycoproteins.  The list includes
           galactose        xylose
           glucose          N-acetylneuramic acid
           mannose          N-acetlygalactosamine
           fucose           N-acetlyglucosamine
           
I know about glucose and galactose.           
My questions are:

    1. Are the the other 6 sugars digested and absorbed?
    2. Once absorbed, are they converted to glucose the way 
       galactose and fructose are?
    3. Are these sugars (besides glucose and galactose, of course)
       used directly for glycoprotein synthesis or are they 
       metabolized for energy?

Any assistance would be greatly appreciated.

Dr. Marion
amarion at charity.trinityvt.edu