Are the 8 principal sugars in glycoproteins "essential sugars"? Are there "essential sugars"? Some have suggested that the 8 principal sugars found in glycoproteins are "essential sugars": 1. Galactose 2. Glucose 3. Mannose 4. N-Acetylneuraminic acid 5. Fucose 6. N-Acetylgalactosamine 7. N-Acetylglucosamine 8. Xylose I realize the liver can convert glucose to many different sugars, so by "essential sugar" I mean a sugar that is difficult to obtain from diet or that the liver requires much energy to convert from glucose. How difficult is it for the liver to convert glucose to the other sugars listed above?

**There are no essential sugars.**

In the context of nutrition "essential" usually means "must be obtained from the diet". So for example the amino acid methionine is an essential amino acid (for humans).

Within this definition there are **zero** essential sugars. A Google search for _essential sugars_ reveals lots of sites like this one. The site lists glucose as the first "essential sugar". In fact we can make glucose from a range of other nutrients including amino acids, lactic acid and glycerol. The second sugar on the list is galactose - we can make that from glucose. And so on...