Nutrition

What Are Sugar Alcohols?

Sugar alcohol is neither a sugar nor an alcohol. It comes from fruits, trees, and other plants. It is formed when its sugar source is hydrogenated (1). An enzyme changes the linkage between glucose and fructose in sucrose (sugar) and two hydrogen atoms are added to oxygen. An alcohol group is attached to the molecule.

Sugar alcohol is considered a "nutritive sweetener". (Non-nutritive sweeteners include Equal, Sweet'n Low, and Splenda, and basically have no calories.) The FDA considers these food products safe.

Sugar alcohols or "polyols" generally have half the sweetness and half the calories of sugar, so this is why they are frequently used by the food industry to sweeten foods. They also may reduce the risk for dental caries. Sugar has 4 calories per gram and sugar alcohols have about 2 calories per gram. Sugar alcohols are low-digestible carbohydrates and are absorbed slowly and incompletely, having a smaller effect on blood glucose (1). However, consuming large amounts can add up and affect both your blood glucose and calorie intake. It is generally agreed that if a food has about 5 or less grams of sugar per serving, the effect on blood glucose is minimal. The total grams of carbohydrate on the food label include sugar and sugar alcohol. The serving size is at the top of the label. If a food contains just one sugar alcohol, then it is listed individually on the food label, but if there is more than one sugar alcohol, the label will say, "sugar alcohols".

The following are sugar alcohols:
Sorbitol
Lactitol
Xylitol
Mannitol
Maltitol
Erythritol
Dulcitol
Starch hydrolysates
Isomalt

It may be helpful to remember the following about sugar alcohols:

1. The relationship to sugar - when reading the food label, take the number of grams of sugar alcohol and divide in half. For example, if a food label has no sugar but has 18 grams of sugar alcohol, this is actually equal to about 9 grams of sugar. Go easy, the food still has about twice the recommended sugar per food serving; remember, we recommended about 5 or less grams of sugar per serving (fruit or milk will naturally have about 15 grams of sugar per serving). So in this case, if the food serving is "4 pieces of candy", you may want to only have "2 pieces of candy" so that the actual sugar equivalent is closer to the recommended 5 grams. If the food label also shows sugar, this has to be counted, too.

2. The relationship to carbohydrate - if all the grams of carbohydrate come from sugar alcohol and the grams of sugar alcohol are less than 10, it can be considered a free food. If the grams of sugar alcohol are greater than 10, subtract half of the sugar alcohol grams from the total carbohydrate grams and count the remaining grams as actual carbohydrate. For example, if the label shows 14 grams of sugar alcohol and 30 grams of total carbohydrate (14 - 7 = 7 and 30 - 7 = 23), there are 23 grams of actual carbohydrate (1).

3. Sugar alcohols are absorbed slowly and incompletely and large amounts may cause abdominal swelling, bloating, or diarrhea.

Hopefully, this will be helpful to you as you navigate the informative FDA food label!

Bon appetit!

More on Sugar Alcohols
Insulin is needed to get glucose in the blood into the liver, muscle, and fat cells. Insulin is not needed to get glucose into the nerve, eye (lens, retina), kidney, blood vessel, and islets of Langerhans (pancreas) cells. You may have heard of the "sorbitol pathway" (2). This pathway occurs when glucose in the cells (eyes and nerves) is converted to sorbitol (sugar alcohol) and then to fructose. Sorbitol and fructose are slowly metabolized and accumulate in the eyes and nerves, allowing water to enter with subsequent swelling, electrolyte imbalance, and cellular dysfunction. This can lead to diabetes complications in the eyes and nerves. This sorbitol pathway reduces intracellular levels of another sugar alcohol, myoinositol, which can result in reduced intracellular sodium and potassium activity.

However, please note that the sorbitol pathway explained above has nothing to do with foods that contain sorbitol (a sugar alcohol). The sorbitol pathway is a metabolic pathway that starts with blood glucose in the cells (eyes and nerves). Since very little sorbitol or other sugar alcohols in food are absorbed from the intestinal tract, they cannot reach levels in the blood or tissues associated with eye, nerve, or kidney damage.

Warshaw, HS & Powers , MA (1999). A Search for Answers About Foods with Polyols (Sugar Alcohols). The Diabetes Educator , 25(3), 307-321.
Powers, MA , Ed. (1996). Handbook of Diabetes Medical Nutrition Therapy MD: Aspen Publishers, Inc.