Xylitol

A natural sugar found in plums, strawberries, and raspberries, xylitol is used as a sweetener in some sugarless gums and candies. Not only does xylitol replace sugars that can lead to tooth decay, it also appears to help prevent cavities by inhibiting the growth of bacteria that cause cavities, such as Streptococcus mutans. Xylitol also inhibits the growth of a related species, Streptococcus pneumoniae, which is a cause of ear infections. Gums, toothpaste and candy containing high levels of xylitol are beginning to become available in the United States.

Many studies, including several under the auspices of the World Health Organization, have evaluated xylitol for preventing dental cavities, with good results. In all cases, xylitol users had fewer cavities than those receiving either placebo or no treatment. In children, another sugar substitute called sorbitol generally had effects similar to xylitol, but xylitol may work better in preventing cavities in permanent teeth. Most studies have used xylitol gum; however, xylitol toothpaste also seems to prevent cavities, although not to the same degree as the gum. Xylitol is thought to prevent cavities by inhibiting the growth of the Streptococcus mutans bacteria. Since a related bacteria, Streptococcus pneumoniae, can cause ear infections, xylitol has been investigated as a preventive treatment for middle ear infections, with some success. Researchers discovered that xylitol does indeed inhibit Streptococcus pneumoniae, and might also work against Haemophilus influenza (another bacteria that causes ear infections). Two well-designed studies enrolling a total of 1,163 children found that chewing gum and syrup sweetened with xylitol helped prevent middle ear infections and decreased the need for antibiotics in treating these infections. Although xylitol did not absolutely prevent ear infections, it significantly decreased the rate at which they occurred.

Preventing Cavities
  Double-blind studies of almost 4,000 people, mostly children, have found that xylitol significantly reduces cavities as compared to individuals given placebo or no treatment. These trials used xylitol-sweetened gum, candies, or toothpaste.
In one of the largest of these trials, researchers tested gum sweetened with various concentrations of xylitol and/or sorbitol against gum sweetened with sucrose and a control receiving no gum.20 This 40-month trial was completed by 861 children. Gum containing 100% xylitol reduced cavities the most. However, all of the xylitol and sorbitol gum groups showed significant reductions in cavities as compared to the control group. In contrast, the children receiving sucrose-sweetened gum had a slight increase in cavities compared to the control group.
A double-blind placebo-controlled study of 1,677 children compared a standard fluoride toothpaste with a similar toothpaste that also contained 10% xylitol. Over the 3-year study period, children given the xylitol-enriched toothpaste developed significantly fewer cavities than those in the fluoride-only group.
Studies in adults and children have shown similar results for xylitol gum and candy.
Another series of studies suggests that children acquire cavity-causing bacteria from their mothers; regular use of xylitol by a mother of a newborn child may provide some protection to the child, as well.
In addition, preliminary evidence suggests that use of xylitol may offer some protection against periodontal disease (gum disease). Ear Infections
  One large double-blind placebo-controlled trial of 857 children investigated how well xylitol (in chewing gum, syrup, and lozenges) could prevent ear infections. The gum was most effective, reducing the risk of developing ear infections by a full 40%. Xylitol syrup was also effective, but less so. The lozenges weren't effective; researchers speculated that children got tired of sucking on the large candies and didn't get the proper dose of xylitol. (In addition, the children were able to distinguish between the xylitol and placebo lozenges by taste, making that portion of the study single-blind.)
Similarly positive results had been seen in an earlier double-blind study by the same researchers, evaluating about 300 children. However, these studies were of short duration and did not test the long-term effect of xylitol in young children and infants, who are most at risk of contracting ear infections.

In the studies described above, dosages for cavity prevention ranged from 4.3 to 10 g per day. The doses were divided throughout the day, usually after meals. For ear infections, children given xylitol-sweetened gum received 8.4 g of xylitol daily, also in divided doses. Those who took syrup received 10 g daily.

Xylitol is believed to be safe, but doses higher than 30 g per day can cause stomach discomfort and possibly diarrhea. In studies, children taking xylitol syrup tended to have more such side effects than those using other forms of xylitol, possibly because it reached the stomach in a more concentrated dose.