All About
Sweeteners
by D. Eric Walters, Ph.D.
by D. Eric Walters, Ph.D.
Artice of the week:
Xylitol
Other names:
Birch sugar
Pentane- 1,2,3,4,5-pentanol
Xylite
Eutrit
Kannit
Klinit
Kylit
Newtol
Torch
Xyliton
Taste:
Xylitol is about equal in sweetness to sucrose. It also produces a cooling feeling in the mouth. It is used primarily in chewing gums and confections.
Calories:
Xylitol could, in principle, provide about 4 calories per gram, just like sugars. But it is only partially absorbed and metabolized, as discussed in the "Safety" section below. The amount that is absorbed may vary depending on the amount consumed and depending on individual differences. For labeling purposes, xylitol is considered to provide 2.4 calories per gram.
Safety:
Xylitol is absorbed by passive diffusion (most sugars are actively transported into the body). It is therefore absorbed more slowly, and absorption is usually incomplete. This can be an advantage in terms of calorie reduction, but it can cause adverse effects if large quantities (over 50 grams) are consumed. First, bacteria in the colon may ferment xylitol, producing gas and acids. Second, the acids and the undigested xylitol can osmotically draw water into the colon, leading to diarrhea. Over time, people who consume large quantities of xylitol may develop different populations of bacteria and adapt to these effects.
Xylitol has been shown to reduce incidence of dental caries[1,2]. Bacteria in the mouth normally utilize sugars to make insoluble glucan, which adheres to teeth. They also produce acids, which can dissolve calcium and phosphate in tooth enamel. Xylitol is not efficiently used by bacteria, so it slows their growth and inhibits acid production. It also appears to prevent adhesion, either by decreasing production of insoluble glycan, or by preventing the adhesion of the glycan. Finally, when used in chewing gum, xylitol stimulates saliva flow, and increased saliva flow also inhibits carie formation.
Recent studies suggest that xylitol may facilitate remineralization of teeth[3]. Combining a calcium source with xylitol in a chewing gum provided better effects than the xylitol alone.
Xylitol seems to be particularly toxic for dogs--it rapidly raises insulin levels and causes liver damage[4]. So keep xylitol-sweetened gum and candy out of reach of your pets!
Chemistry:
Molecular formula: C5H12O5
Molecular weight: 152.15
Xylitol is a sugar alcohol (or polyol)--a substance that has many hydoxyl (alcohol) groups, as carbohydrates do.
Properties:
Xylitol is stable over the range of pH found in foods. It is also heat-stable. It is highly soluble in water (64.2 g/100 mL).
Sources:
Xylitol is present naturally at low levels in raspberries, plums, and some other fruits. It was first produced for food use in Finland from birch trees. It is now produced commercially from additional sources such as corn and sugar cane stalks.
References:
1. Maguire, A.; Rugg-Gunn, A.J. Xylitol and caries prevention - is it a magic bullet? Brit. Dental J. 194:429-436 (2003). PubMed link
2. Burt, B.A. The use of sorbitol- and xylitol-sweetened chewing gum in caries control. J. Amer. Dental Assoc. 137:190-196 (2006). PubMed link
3. Suda, R.; Suzuki, T.; Takiguchi, R.; Egawa, K.; Sano, T.; Hasegawa, K. The effect of adding calcium lactate to xylitol chewing gum on remineralization of enamel lesions. Caries Res. 40:43-46 (2006). PubMed link
4. Dunayer, E.K.; Gwaltney-Brant, S.M. Acute hepatic failure and coagulopathy associated with xylitol ingestion in eight dogs. J. Amer. Vet. Med Assoc. 229:1113-1117 (2006). PubMed link
Other links:
Xylitol on Wikipedia
SweetenerBook.com
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