Scientific Name(s): Pentahydroxypentane, Xylo-1,2,3,4,5-pentol
Common Name(s): Birch sugar, Xylitol
Xylitol is a 5-carbon sugar alcohol naturally found in the fibers of many fruits and vegetables, including raspberries, strawberries, yellow plum, lettuce, cauliflower, corn, and corn husks.1, 2, 3, 4 It is a natural product that may be extracted from the bark of birch trees and other hardwood species containing xylan.2, 5 The commercial chemical process for producing xylitol was developed in the 1970s in Finland.6, 7
Xylitol was first discovered in 1891 by a German chemist, Emil Fischer.2 This natural sweetener was used in the sugar shortages of World War II in the 1930s in Finland. During the 1960s, the product was marketed in Germany, Switzerland, the Soviet Union, Japan, Italy, and China.2 It was approved by the FDA in 1963 as a food additive.8, 9 It is currently approved for use in foods, pharmaceuticals, oral health products, and nutraceuticals in more than 35 countries.5, 10 Some commercially available xylitol-containing products include gums, mints, energy bars and foods, oral hygiene products, and vitamins.5
In Europe, Korea, Japan, Thailand, and China, chewing gum and lozenges containing xylitol are widely available and used by consumers. Finland implemented a national campaign and was the first country to promote xylitol to reduce tooth decay in children. Other European and Asian countries, including Japan and Korea, implemented similar programs, in which xylitol chewing gum has captured nearly 50% of the commercial chewing gum market. Even the US Army implemented an initiative to promote xylitol to improve oral health among deployed troops. Xylitol chewing gum and hard candy products are considered choking hazards in young children; therefore, initiatives addressing tooth decay in young children have not been adopted until the creation of an acceptable xylitol delivery vehicle.8
Xylitol is a natural carbohydrate and is classified as a polyhydric alcohol or sugar alcohol. All 5 carbon atoms bind to a hydroxide group; thus, the molecule has no reducing groups. A review article documents the chemical profile and clinical structural importance (ie, the pentitol-hexitol theory) of xylitol.1
Xylitol is a normal intermediate of human metabolism and the human body produces nearly 5 to 15 g daily, with nearly 80% metabolized by the liver.1, 3 Xylitol is almost identical in sweetness and bulk to sucrose, has 40% fewer calories, and an energy value of 2.4 versus 4 calories per gram of sucrose. One teaspoonful of xylitol contains approximately 10 calories, while 1 teaspoonful of sucrose contains 15 calories.
Industrially, xylitol is produced by chemical hydrogenation of D-xylose into xylitol by the presence of a nickel catalyst.2, 3, 7 Direct extraction from the birch tree bark leads to the most pure and desirable product, but the process is expensive and uneconomical.3 The xylitol yield ranges from 50% to 60% from the total xylan content of the wood hemicellulose, and annual production is estimated at 20,000 to 40,000 tons per year.7
Alternative forms of industrial production of xylitol, such as the use of metabolically engineered yeasts, have been studied.7
Uses and Pharmacology
Medical literature documents the use of xylitol in medical conditions and applications, including acute otitis media, dental caries, IV nutrition, and osteoporosis.
Acute otitis media (middle ear infections)
The mechanism of action for xylitol may involve altering the adherence surface by potentially blocking bacterial lectins.1, 11 Another mechanism may involve xylitol being metabolized to xylitol-5-phosphate, which may be toxic to bacteria.12
In-vitro and animal data
A 5% concentration of xylitol inhibited the growth of Streptococcus pneumoniae. The xylitol-induced inhibition of S. pneumoniae is mediated through a fructose phosphotransferase system.12 Xylitol also reduces the level of adherence of S. pneumoniae and Haemophilus influenzae to nasopharyngeal epithelial cells. In addition, xylitol affects the expression of the polysaccharide capsule and cell wall of pneumococci. However, xylitol does not affect nasopharyngeal colonization of pneumococci.11, 13, 14
Dietary xylitol may improve oxidative killing in neutrophilic leukocytes and prolong the survival of rats suffering from sepsis caused by S. pneumoniae.15 Parenteral xylitol has a nitrogen-sparing effect and improves the survival of rats suffering from intestinal sepsis.16
According to the results of 2 randomized, double-blind trials, the occurrence of acute otitis media was reduced by 40% in children given xylitol chewing gum. The daily dose varied from 8.4 g in chewing gum to 10 g in syrup and reduced the need for administration of antibiotics.17, 18 Xylitol oral solution at dosages of 5 g orally 3 times a day and 7.5 g orally once a day was well tolerated in young children.19 Inhalation of aerosolized iso-osmotic xylitol was well tolerated in human volunteers and did not induce any changes in electrolytes and osmolarity.20 Airway deposition and retention time of aerosolized xylitol was roughly 3 hours.21 An updated Cochrane review identified 5 randomized clinical trials and quasi-randomized clinical trials (N=3,405) that met inclusion for a systematic review and meta-analysis of xylitol for preventing acute otitis media (AOM) in children up to 12 years of age. Moderate-quality evidence supported a risk reduction in AOM of 22% to 30% with prophylactic use of any form of xylitol in healthy children attending daycare (dose, 8 to 10 g/day). However, this benefit appeared to be lost in children with an existing respiratory infection or who were prone to AOM (moderate-quality and low-quality evidence, respectively) even at doses of up to 15 g/day.50
Bowel motility restoration
Postoperative restoration of bowel motility was found to be significantly improved in patients who were given xylitol gum to chew after surgery. In a randomized controlled trial, 109 patients requiring laparoscopic surgery for benign or malignant gynecologic disease received usual postoperative care plus either mint-flavored, sugarless xylitol chewing gum 3 times daily (to be chewed for 30 minutes at each session starting 6 hours after surgery until first flatus) or no gum. First flatus and first bowel sounds were observed significantly earlier in the treatment group (P < 0.001 for each); however, no significant difference was seen in postoperative GI complications between groups.49
Xylitol inhibits the cariogenicity, adhesivity, and acidogenic potential of plaque.1
A literature review of randomized controlled trials and observational studies involving nearly 12,000 patients supports the use of polyol-containing chewing gums in reducing dental caries.22 Enamel demineralization is prevented, and plaque building bacteria do not proliferate because xylitol is not fermented by the bacteria.23 Remineralization is enhanced because xylitol does not decrease pH and, thus, helps reduce plaque accumulation on the tooth surface. Dental caries reduction results from the buffering effect on plaque from saliva stimulation throughout the chewing process.23, 24 Also, cariogenic microorganisms cannot metabolize polyols into acids because sucrose is replaced with xylitol.8, 24 Studies have explored the safety and efficacy of xylitol delivery vehicles, such as gummy bear snacks and syrups in organized caries prevention programs in schools and daycare centers for small children.8, 9, 10 A Cochrane review of xylitol-containing products for preventing dental caries in children and adults identified 10 randomized controlled trials (N = 5,903), most of which had a high risk of bias. Low-quality evidence suggested that 2.5 to 3 years use of fluoride toothpaste containing 10% xylitol may reduce caries in the permanent teeth by 13%, compared to fluoride-only toothpaste. Remaining data was of insufficient quality to make any determinations regarding other monitored parameters.48 A small non-blind pilot study in 41 adolescents and young adults undergoing fixed-appliance orthodontic treatment evaluated the long-term effect of xylitol supplementation on caries risk. Compared to the control group, supplementation with xylitol 6 g/day (as gum or mint) for 3 months was not found to provide any significant difference in the ecology of dental plaque or saliva over the 12-month follow-up period.51 Similarly, short-term chewing of 6 g/day of xylitol gum for 5 weeks did not significantly change the salivary microbial composition in Kuwait children.52
Xylitol is a low-calorie sweetening alternative and is absorbed more slowly than sugar. It contains 40% fewer calories and does not cause increased blood sugar levels, because it is metabolized independently of insulin.1, 5, 35, 36
Xylitol inhibited the major periodontopathogen Porphyromonas gingivalis, which is responsible for the initiation and progression of periodontitis by reducing inflammatory cytokine expression.37
In parenteral nutrition, xylitol is often given with amino acids and other carbohydrates. Metabolically, parenterally administered xylitol products reduce gluconeogenesis, promote fatty acid oxidation, and moderate blood glucose and insulin levels.1, 25, 26, 27 Numerous studies document how xylitol was more effective than glucose during total parenteral nutrition after trauma and sepsis. Because high plasma glucose concentrations are avoided, high hepatic glucose production is reduced and the release and oxidative use of free fatty acids is enhanced.25, 26, 27
Three primary metabolic advantages over D-glucose include:
Xylitol reduces insulin secretion and hepatic lipogenesis when compared with D-glucose;
the flow of amino acids from peripheral tissues to visceral organs remains undisturbed;
xylitol enters the pentose phosphate cycle directly, without insulin.
Myoadenylate deaminase deficiency
Dietary xylitol increases the intestinal absorption of calcium and when added to calcium supplements, accelerates bone repair and improves the bioavailability of calcium salts in calcium-deficient rats.28 In streptozotocin diabetic rats, dietary xylitol reduced loss of bone mineral and trabecular bone volume, and improved bone biomechanical properties.29 A 10% (wt/wt) dietary xylitol supplement has been used in most animal studies, corresponding to a daily intake of approximately 2 g of xylitol or 40 g total daily intake in humans.30, 31 The metabolism of xylitol also improves collagen synthesis and glycosylation.32 Xylitol also protects against ethanol-induced bone resorption33 decreased trabecular bone volume, and the early phase of collagen type II–induced arthritis.34
Dosage regimens vary in clinical studies. In one study to prevent ear infections in children, the daily dose varied from 8.4 g in chewing gum to 10 g in syrup.17, 18 Xylitol oral solution at dosages of 5 g orally 3 times a day and 7.5 g orally once a day was well tolerated in young children.19 Xylitol chewing gum was effective in reducing dental caries when divided into at least 3 consumption periods per day for a total dose of 6 to 10 g.9 Numerous foods and pharmaceutical and commercial products contain xylitol. Research has shown that xylitol lozenges (1 g xylitol, 5 times daily) reduced the caries increment 10 percent. This reduction, representing less than one-third of a surface per year, was not statistically significant.47
Pregnancy / Lactation
Pregnancy: Category B. Xylitol is considered safe in pregnancy and during breast-feeding, according to the FDA.39 The use of xylitol chewing gum in mothers lowered maternal oral bacterial load and reduced transmission of mutans streptococci to infants late in pregnancy and during the postpartum period.40, 41 The optimal dose of xylitol for prevention is not known.1, 39, 40, 41
Patients should be counseled if taking laxative products, because most sugar alcohols may have an additive laxative effect; sugar alcohols are not fully broken down during digestion. Xylitol appears to protect against ethanol-induced bone resorption and trabecular bone mineral density changes.33
Avoid use in individuals allergic to xylitol. Hypersensitivity reactions are documented in the medical literature.42
The main adverse effects reported from oral xylitol use at a dosage exceeding 40 to 50 g/day included nausea, bloating, borborygmi (rumbling sounds of gas moving through intestine), colic, diarrhea, and increased total bowel movement frequency.43 Oral erosive eczema from xylitol is also documented.34 No major changes in serum electrolytes were documented with a xylitol infusion, and parenteral xylitol resulted in minimal hyperuricemia without any pathophysiological consequences in human patients.20
Xylitol is generally nontoxic, considering the data from various clinical studies and its historical use in foods, pharmaceuticals, and nutraceuticals. Animal studies also confirm its overall safety profile.44 Renocerebral oxalosis with renal failure is documented with large doses of IV-administered xylitol.20, 45 A dog suffered vomiting, mild hypoglycemia, and fulminant hepatic failure after ingesting half of a loaf of bread containing xylitol.46
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