Polyols such as sorbitol and xylitol, also known as sugar alcohols, are low-digestible sugar replacers that can replace sugar spoon for spoon. Most polyols are not as sweet as sugar, and since they are incompletely digested, they have fewer calories. Because polyols are only partially digested and absorbed in the small intestine, they travel to the large intestine where they may be fermented by bacteria. The fermentation of non-digested carbohydrates leads to the production of compounds that, for example, serve as nutrients for colon cells and result in the formation of gas which leaves the body in form of flatulence. Additionally, water follows the undigested and unabsorbed polyols into the large intestine, and is re-absorbed. The extent of this water absorption is dependent upon the individual’s capacity to do so. Non-absorbed water softens the feces and is eliminated in the feces. Thus, consumption of polyols may lead to a slight increase in the frequency of bowel movements and a softer consistency of the feces. These fermentation and laxative effects are common for all non-digestible carbohydrates and foods rich in them, such as beans, cabbage, onions, grapes, prunes, and other high-fiber foods.
The perception of the effects of polyols may be varied, as people respond differently. For example, some people may be troubled while others perceive them as signs of a “fiber-working” effect. On the other hand, effects can vary for different persons or on different occasions depending on an individual’s sensitivity as well as the amount of polyol eaten at one time, the type of polyol consumed, and other foods eaten with the polyol-containing product. When a polyol-containing food is eaten as part of a meal, the transit time through the gastrointestinal (GI) tract is lengthened, allowing more water to be absorbed and more of the polyol to be fermented in the large intestine. This means that GI effects are reduced or may not be perceived at all. Likewise, if the polyol-containing food is consumed slowly over time, this would be beneficial in a similar way. Consuming polyol-containing products frequently increases tolerance and decreases gastrointestinal side effects because of a preferential increase in bacteria capable of metabolizing the polyol.
The characteristics of polyols leading to their benefits (i.e. toothfriendly properties, very low rise in blood glucose levels, fewer calories) as well as gastrointestinal effects are essentially the same for all polyols, thus all may induce laxation when eaten in large quantities (physiological overload). “Normal” bowel function varies widely between individuals, and so too does the perception of digestion. Any GI effects from consuming foods with polyols, if they occur at all, are usually mild and temporary. If a person believes she/he is negatively affected, the amount eaten on a single occasion should be reduced. Most people will adapt to polyols after a few days, the same way they do to other high fiber foods. Many people have learned to eat only a small amount of sugar-free products at first and then to gradually increase these foods in the diet. As with any other food, consume foods containing polyols in moderate amounts.