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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?

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closed as too broad by Chris, MattDMo, jonsca, WYSIWYG, leonardo Feb 27 at 2:38

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

    
Your main question can be answered by simply copy/pasting it into google. Did you try to research this before posting? I assume you did, so what is it that was unclear to you? –  terdon Feb 25 at 15:43
    
that wasn't so classy changing the question when we tried to answer your original one. oh well. –  shigeta Feb 25 at 22:29
    
@shigeta: Well, the question was about to be deleted anyways… –  Geremia Feb 26 at 1:12
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2 Answers 2

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...

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To put it in hard words: Its pseudoscientific bullsh*t. –  Chris Feb 25 at 16:50
    
By "essential" I mean "difficult to synthesize of not obtained from the diet." –  Geremia Feb 25 at 20:36
    
I think you will have to define "difficult". But really, now that you have edited your question, you are asking for an entire chapter from a biochemistry textbook. –  Alan Boyd Feb 25 at 21:31
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@AlanBoyd is right that the term 'essential sugar' is not a scientific or biologically defined term and is not true given the meaning of the word essential that is in use in biology.

In alternative health and diet circles, the term 'essential sugars' refers to a set of simple carbohydrates which are hypothesized to be important for good health and nutrition in people.

Even if this were a valid approach in humans its very unlikely to be the same specific sugars and proportions for other animals and living things.

So given all these caveats the reference I found for 'essential sugars' lists these 8: glucose, galactose, fucose, mannose, glucosamine, galactosamine, neuraminic acid, and xylose.

As far as whether this really helps us, I personally don't think this is the key to good health in and of itself. It really oversimplifies all of the biomachinery we have to break down and utilize carbohydrates.

As the diet recommends the eating of vegetables which aren't too green, avoiding fructose, it doesn't seem to hurt. Carbohydrates from food are often the product of breaking down complex carbohydrates. I feel as if watching the glycemic index of your food and avoiding soft drinks and too much fruit juice will get you further in terms of health. Avoiding simple carbohydrates entirely in your diet also has advocates and there is some medical research that backs it up.

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I don't even see reason to avoid frucose, since the body can make frucose-6-phosphate from glucose-6-phosphate. Frucose, which the cells take up also get phosphorylated, so this doesn't make any difference. –  Chris Feb 25 at 17:35
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thanks for mentioning. I take it you mean fructose? That part about not taking in high fructose has some pretty good science behind it. In humans (and rats etc) fructose is only metabolized in the liver so when you have a large ingestion of fructose the local concentration in the liver becomes very high and it manufactures fat as opposed to breaking down to other carbohydrates. sciencedirect.com/science/article/pii/S0168827808001645 –  shigeta Feb 25 at 18:16
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Yeah, I mean fructose, damn typos. But it doesn't make too much sense to worry only about one carbohydrate. Nutrition has to be balanced, so if we avoid fructose, but live otherwise unhealthy (meaning too much fat and so on) this will change nothing. –  Chris Feb 25 at 18:24
    
hey @Chris - that's biochemistry for ya - the devil's in the details :) in general engineered foods are suspect as far as i'm concerned and probably aren't healthy as they are not a product of the environment we evolved from - my soapbox... –  shigeta Feb 25 at 18:54
    
I am a biochemist :-) And I don't worry too much about food - but I try to avoid a few things. –  Chris Feb 25 at 19:29
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