Sugar(s) can provide a lot of calories and contribute to tooth decay. Thus there are many other compounds that are used as alternatives to sugar that have been developed or discovered. We will first consider sugar alcohols and then the alternative sweeteners in subsequent sections.
Below you can see the structure of three common sugar alcohols: xylitol, sorbitol, and mannitol.
Figure 2.121 Structure of three commonly used sugar alcohols: xylitol, sorbitol, and mannitol1-3
Remember that alcohol subgroups are (OH), and you can see many of them in these structures.
Sugar alcohols are also known as "sugar replacers", because some in the public might get confused by the name sugar alcohol. Some might think a sugar alcohol is a sweet alcoholic beverage. Another name for them is nutritive sweeteners, which indicates that they do provide calories. Sugar alcohols are nearly as sweet as sucrose but only provide approximately half the calories as shown below. The name polyols also seems to be increasingly used to describe these compounds.
Table 2.121 Relative sweetness of monosaccharides, disaccharides, and sugar alcohols4,5
|Sweetener||Relative Sweetness||Energy (kcal/g)|
*Differs based on a person’s lactase activity
Sugars are fermented by bacteria on the surfaces of teeth. This results in a decreased pH (higher acidity) that leads to tooth decay and, potentially, cavity formation. The major advantage of sugar alcohols over sugars is that sugar alcohols are not fermented by bacteria on the tooth surface. There is a nice picture of this process in the link below as well as a video explaining the process of tooth decay.
While not a sugar alcohol, tagatose is very similar to sugar alcohols. Tagatose is an isomer of fructose, that provides a small amount of energy (1.5 kcal/g). 80% of tagatose reaches the large intestine, where it is fermented by bacteria, meaning it has a prebiotic-type effect3. Notice the similarity in structure of tagatose to sugar alcohols, the only difference being a ketone (=O) instead of an alcohol (OH) group.
Figure 2.122 Structure of tagatose11
References & Links
- Wardlaw GM, Hampl J. (2006) Perspectives in nutrition. New York, NY: McGraw-Hill.
- Whitney E, Rolfes SR. (2008) Understanding nutrition. Belmont, CA: Thomson Wadsworth.
Sugar and Dental Caries - http://www.asu.edu/courses/css335/caries.htm
Tooth Decay - http://www.youtube.com/watch?v=_oIlv59bTL4