Sugar isomers

[genovese]

The human body utilizes glucose and other sugars in the D-isomer form.
Is the L isomer form sweet tasting and could the L form be used as a food sweetner or is it dangerous for human consumption?

[mith]

http://en.wikipedia.org/wiki/Tagatose
Not quite

[genovese]

Thanks - that's really interesting. I can't imagine why they cannot find a commercial market for it! If it doesn't require insulin and doesn't affect blood glucose levels I would have thought that it could be used for diabetics.

I assume from the article that no sweetening effect has been found to occur with the L-isomers of the standard sugars since Tagatose is still in the D form.

[Cat]

L-isomers taste the same as regular. They are expensive to produce and like all other sugar substitutes that are not metabolized properly, have a tendency to cause diarrhea. Diabetics that need insulin cannot avoid glucose intake from other carbohydrates (cereals, vegis, fruits, etc.), so while sugar substitutes are used by diabetics in place of sucrose, they are not substitutes for insulin or other "sugar pills".

[genovese]

Yes, thank you Cat. I do realize that unabsorbed sugars cause diarrhea via osmosis in the gut; not too bad a way of reducing absorption of glucose and reducing blood glucose levels and therefore reducing need for so much insulin. Also most type II diabetics tend to be overweight, so a little malabsorption might not be such a bad thing if you just want the taste of sweetness without nutrition and lose a bit of weight at the same time.

I suspect, as you say, it is the price of producing the L-isomers that is prohibitive.

[mith]

There's lots of natural sweeteners other than sugar

[genovese]

Yes - how safe are they for long term use?
I was hoping that a "natural sugar" in the unabsorbable L configuration might be without dangerous side effects.

[mith]

The chinese use this fruit called "lo han guo" which I guess is safe since we've been using it for thousands of years.

I think left-handedness of regular chemicals doesn't necessarily make it safe. For example, thalidomide the commonly used drug for morning sickness also causes birth defects. One enantiomer is the drug, the other is a poison.

[MichaelXY]

I thought they banned the use of thalidomide for morning sickness in the sixties due to all the birth defects.

[canalon]

Yes they did, because they cannot separate the 2 enantiomers.

[MrMistery]

By the way, most sweets for diabetics are based on fructose...