A sugar alcohol (also known as a polyol, polyhydric alcohol, polyalcohol, or glycitol) is a hydrogenated form of carbohydrate, whose carbonyl group (aldehyde or ketone, reducing sugar) has been reduced to a primary or secondary hydroxyl group (hence the alcohol). Sugar alcohols have the general formula H(HCHO)n+1H, whereas sugars have H(HCHO)nHCO. In commercial foodstuffs sugar alcohols are commonly used in place of table sugar (sucrose), often in combination with high intensity artificial sweeteners to counter the low sweetness. Of these, xylitol is perhaps the most popular due to its similarity to sucrose in visual appearance and sweetness. Sugar alcohols do not contribute to tooth decay.
However, consumption of sugar alcohols does affect blood sugar levels, although less than that of "regular" sugar (sucrose). Sugar alcohols may also cause bloating and diarrhea when consumed in excessive amounts.
Some common sugar alcohols:
Both disaccharides and monosaccharides can form sugar alcohols; however, sugar alcohols derived from disaccharides (e.g. maltitol and lactitol) are not entirely hydrogenated because only one aldehyde group is available for reduction.
Sugar alcohols as food additives 
|Name||Sweetness relative to sucrose||Food energy
food energy, relative to sucrose
As a group, sugar alcohols are not as sweet as sucrose, and they have less food energy than sucrose. Their flavor is like sucrose, and they can be used to mask the unpleasant aftertastes of some high intensity sweeteners. Sugar alcohols are not metabolized by oral bacteria, and so they do not contribute to tooth decay. They do not brown or caramelize when heated.
In addition to their sweetness, some sugar alcohols can produce a noticeable cooling sensation in the mouth when highly concentrated, for instance in sugar-free hard candy or chewing gum. This happens, for example, with the crystalline phase of sorbitol, erythritol, xylitol, mannitol, lactitol and maltitol. The cooling sensation is due to the dissolution of the sugar alcohol being an endothermic (heat-absorbing) reaction, one with a strong heat of solution.
Sugar alcohols are usually incompletely absorbed into the blood stream from the small intestines which generally results in a smaller change in blood glucose than "regular" sugar (sucrose). This property makes them popular sweeteners among diabetics and people on low-carbohydrate diets. However, like many other incompletely digestible substances, overconsumption of sugar alcohols can lead to bloating, diarrhea and flatulence because they are not absorbed in the small intestine. Some individuals experience such symptoms even in a single-serving quantity. With continued use, most people develop a degree of tolerance to sugar alcohols and no longer experience these symptoms. As an exception, erythritol is actually absorbed in the small intestine and excreted unchanged through urine, so it has no side effects at typical levels of consumption.
The table above presents the relative sweetness and food energy of the most widely-used sugar alcohols. Despite the variance in food energy content of sugar alcohols, EU labeling requirements assign a blanket value of 2.4 kcal/g to all sugar alcohols.
People who have undergone gastric bypass surgery, specifically Roux-en-Y gastric bypass (RGB), should be careful not to eat too many sugar alcohols as doing so, with the exception of erythritol, can lead to "dumping".
See also 
- "Sugar Alcohols". The Sugar Association, Inc. 2012. Retrieved 2012-10-10.
- "Role of Sugar-Free Foods and Medications in Maintaining Good Oral Health". American Dental Assoiation. 2002-06-05. Retrieved 2010-08-01.
- Bradshaw, DJ; Marsh, PD (1994). "Effect of Sugar Alcohols on the Composition and Metabolism of a Mixed Culture of Oral Bacteria Grown in a Chemostat.". Caries Research 28 (4): 251–256. doi:10.1159/000261977. PMID 8069881
- "Eat any sugar alcohol lately?". Yale-New Haven Hospital. 2005-03-10. Retrieved 2012-06-25.
- Cammenga, HK; LO Figura, B Zielasko (1996). "Thermal behaviour of some sugar alcohols". Journal of thermal analysis 47 (2): 427–434. doi:10.1007/BF01983984.