Sugar alcohols are a little strange. They are not exactly a sugar, but they are certainly not alcohol either. (Alcoholic beverages contain ethanol. Sugar alcohols are vaguely related to ethanol, but do not have an intoxicating effect.)
So you won’t get drunk from eating sugar alcohols. But what exactly are they, and why are they used in foods? Here’s an ingredient list from “no sugar added” ice cream that includes 4 different sugar alcohols.
Sugar alcohols are related to sugars. The –OSE ending of a word means that it is a sugar (like sucrOSE or lactOSE). An –OL ending to a word means that it is an alcohol (like sorbitOL or lactitOL).
The chemical structure is similar. Below is the chemical structure of lactose (milk sugar) compared to the chemical structure of lactitol (the comparable sugar alcohol). The ring structure on the left is the same, but the right side of the molecule is different.
|Chemical structure of lactose||Chemical structure of lactitol|
Some sugar alcohols are natural
Some sugar alcohols occur naturally in food. Mannitol is found in some fruits and vegetables. Sorbitol is found in fruits and vegetables, or can be made from corn syrup. Xylitol is found in fruits, vegetables, and some grains.
Why are sugar alcohols used?
Sugar alcohols have less calories than sugars. They are used as “sugar substitutes” in many low sugar or sugar-free foods. Sugar alcohols are not quite sugar free, though. They contain 1.5-3 calories per gram (compared to sucrose, or table sugar, at 4 calories per gram). They are very commonly used in sugar-free gums (sorbitol and xylitol) to make the gum sweet without adding sugar.
How are sugar alcohols digested?
Sucrose, or sugar, is primarily digested in the small intestine (the part right after your stomach). It is broken down and absorbed into the blood as glucose (the simplest form of sugar). Glucose is used by all the cells in your body for energy.
Sugar alcohols, on the other hand, do not get digested in the small intestine. They don’t get digested until they get to the large intestine (the last part of your intestinal tract). The normal bacteria in your large intestine ferment the sugar alcohols into glucose. This normal fermentation causes some gas formation. If sugar alcohols are eaten in large quantities, fermentation can cause gas, bloating, and even diarrhea. (This is why the food label above carries the disclaimer about a laxative effect.) Eating large amounts of fresh fruits and vegetables can also have this effect, from the sugar alcohols and from the fructose (fruit sugar).
Sugar alcohols will cause an increase in blood sugar, but not to the same extent as sugar. If you are diabetic, be sure you know how sugar alcohols will affect your blood sugar and insulin needs.
How do I know if sugar alcohols are in a food?
If you are eating fresh fruits or vegetables, you are probably eating some sugar alcohols.
When you’re grocery shopping, check the food labels. Any food that uses a “sugar free”, “low sugar”, “no added sugar” or “reduced sugar” label (or any other version) and contains sugar alcohols must list these on the nutrition label.
Otherwise, listing the sugar alcohol content in the nutrition facts is optional. (It is still included in the “total carbohydrate” count.) Just like we have seen with calories and sugar, if there is less than 0.5 grams of sugar alcohol per serving, it can be considered to be zero. [These requirements are listed in the FDA Code of Federal Regulations title 21, in section 101.9(c)(6)(iii).]
You can also check the ingredient lists for words like sorbitol, xylitol, mannitol, and lactitol. Even if sugar alcohols are not listed in the nutrition facts, they must be included in the ingredients list if they are used.
The bottom line
Sugar alcohols are a type of sugar substitute that occur naturally in some foods. Sugar alcohols are added to other foods for a sweet taste without adding sugar. Over-eating of foods with sugar alcohols can have some side effects (just like over-eating anything else). The choice is yours if you want to try to limit sugar alcohols in your diet or not.
I’ve got some information planned for fats and cholesterol coming up soon. What other sugar or fat questions do you have about your foods?