Mar 022012
 

Sugar alcohols are formed when the carboxyl (ketone) group of a sugar is changed to a hydroxyl (alcohol) group. There are many sugar alcohols. Here I will the discuss the common ones used in foods and those which may be useful sugar substitutes. Here is a list of the sugar alcohols of interest.

Sugar Alcohol

No. of Carbons

Sweetness

Calories/gr

Glycerol

3

0.6

4.3

Erythritol

4

 0.7

0.2

Xylitol

5

1.6

2.4

Sorbitol

6

0.9

2.6

Maltitol – disaccharide

12

1.7

2.1

Glucose (for comparison)

6

1.0

4.5

All of these are sweet to varying degrees. None of these promote dental decay, as they can not be metabolized by the bacteria that cause it. The simplest sugar alcohol is glycol with two carbons. It is commonly used as antifreeze. It is sweet but is very toxic. All the other sugar alcohols are non toxic. They are of interest because they often behave like sugar in recipes and  they generally taste like sugar. They are natural substances that are for the most part non-toxic. Yet they have low caloric and glycemic characteristics.

For the most part they are absorbed from the intestines poorly. Because of this with excess consumption some sugar alcohols can cause gas pains and diarrhea. Sensitivity varies and with regular exposure some tolerance usually develops. Some of them can be metabolized by humans and some cannot. In the U.S. all sugar alcohols are labeled as having 2.4 Calories per gram. This is absurd as some are absorbed or metabolized significantly at all. The characteristics of each are listed below.

 

 Useful Sugar Alcohols

 

Glycerol

chemical structure of glycerol-3-phosphate

Glycerol


Is not low calorie, but has a low glycemic index. In small quantities it can facilitate energy production and improve hydration of the body. I use it to sweeten my tea. A healthful dose is about 4 Tblsp. Per day.

 Erythritol

Is found in small quantities in some fruits and fermented foods. It is very poorly metabolized making it essentially non-caloric. It is less likely to cause GI upset than some sugar alcohols, as it is 90% absorbed. Most of it is then excreted unchanged in the urine. Like other sugar alcohols it does not promote tooth decay and it exhibits some of the bacteria starving properties of xylitol (see below).

Erythritol is also available as a blend mixed with the herbal sweetener stevia. This minimizes the bitterness often associated with stevia. The blend I use has about twice the sweetness of sucrose for a given measure.

 Xylitol

 

English: Xylitol, structural formula Svenska: ...

Xylitol

Is another naturally occurring sugar alcohol found in small quantities in many fruits and vegetables. It is poorly absorbed so can cause GI upset. It is tolerated less well than erythritol but better than maltitol. It dissolves well in water and does not crystallize back out easily and so works well for sugar-free jams. It has less than half the calories of glucose or sucrose and like other sugar alcohols it has a low glycemic index.

Xylitol is considered a “tooth friendly” sugar alcohol because it inhibits decay causing bacteria and helps re-mineralize the enamel. About 3-6 grams of xylitol per day are needed for dental benefits. Xylitol may also help prevent osteoporosis. Its anti-microbial effects also help prevent ear infections, Candida, and many other infections, and asthma. Some studies show that high does may be toxic in dogs.

 

Sugar Alcohols best avoided

 

Sorbitol

Sorbitol is a sugar alcohol found in small amounts naturally in apples, pears, peaches and prunes. It is used in mouthwashes and toothpastes. It is sometimes used as a sweetener in foods. It is converted to fructose in the liver and probably has all the negative effects of fructose. But it also has a strong laxative effect, so little can be tolerated.

Maltitol

English: A warning sign with an exclamation mark

Maltitol is a disaccharide sugar alcohol made from maltose (two glucose molecules). Its properties make it well suited for sugar free candies, chocolates, chocolates, ice cream, and protein bars. Like sorbitol it has a pronounced laxative effect. BEWARE! Even small quantities can cause bloating and pain in some individuals. In many countries products containing maltitol have a government warning regarding its laxative effects. It contains about 2 Calories per gram and has a lower glycemic index than glucose.

Enhanced by ZemantaThe next article will be on the non-nutritive sweeteners including stevia.

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