| Xylitol[1] | |
|---|---|
Xylitol crystals
|
|
|
(2R,3r,4S)-Pentane-1,2,3,4,5-pentol |
|
|
Other names
1,2,3,4,5-Pentahydroxypentane; |
|
| Identifiers | |
| CAS number | 87-99-0 |
| UNII | VCQ006KQ1E |
| ChEMBL | CHEMBL96783 |
| Properties | |
| Molecular formula | C5H12O5 |
| Molar mass | 152.15 g mol−1 |
| Density | 1.52 g/cm³ |
| Melting point |
92–96 °C |
| Boiling point |
216 °C |
| Solubility in water | ~ 1.5 g/mL |
| Related compounds | |
| Related alkanes | Pentane |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
Xylitol ( /ˈzaɪlɪtɒl/; Greek: ξύλον, xyl[on], "wood" + suffix -itol, used to denote sugar alcohols) is a sugar alcohol sweetener used as a naturally occurring sugar substitute. It is found in the fibers of many fruits and vegetables, and can be extracted from various berries, oats, and mushrooms, as well as fibrous material such as corn husks and sugar cane bagasse,[2][3] and birch. Xylitol is roughly as sweet as sucrose with only two-thirds the food energy.
As with other sugar alcohols, with the exception of erythritol, consumption in excess of one's laxation threshold (the amount of sweetener that can be consumed before abdominal discomfort sets in) can result in temporary gastrointestinal side effects, such as bloating, flatulence, and diarrhea. Adaptation, an increase of the laxation threshold, occurs with regular intake. Xylitol has a lower laxation threshold than some sugar alcohols, but is more easily tolerated than others such as mannitol and sorbitol.[4][5]
Xylitol is an organic compound with the formula (CHOH)3(CH2OH)2. This achiral species is one of four isomers of pentane-1,2,3,4,5-pentol.
Contents |
Xylitol was discovered almost simultaneously by German and French chemists in the late 19th century, and was first popularized in Europe as a safe sweetener for people with diabetes that would not impact insulin levels.[6] Its dental significance was researched in Finland in the early 1970s, when scientists at Turku University showed it had significant dental benefits.[6] Today, using hardwood or maize sources, the largest manufacturer globally is the Danish company Danisco, with several other suppliers from China.[7] Xylitol is produced by hydrogenation of xylose, which converts the sugar (an aldehyde) into a primary alcohol.
100 grams of xylitol contain 1405 kilojoules. One teaspoon (5 g) of xylitol contains 9.6 kilocalories (Cal), as compared to one teaspoon of sugar, which has 15 Cal. Xylitol has virtually no aftertaste, and is advertised as "safe for diabetics and individuals with hyperglycemia." This tolerance is attributed to the lower impact of xylitol on a person's blood sugar, compared to that of regular sugars and also has a very low glycemic index of 13 (glucose has a GI of 100).[8]
Xylitol is used around the world, mainly as a sweetener in chewing gums and pastilles. Other applications include oral hygiene products, such as toothpaste, fluoride tablets and mouthwashes. The pharmaceutical industry uses xylitol as a sweetener in its products.[9]
Xylitol is a “tooth-friendly”, nonfermentable sugar alcohol.[10][11] A systematic review study[12] on the efficacy of xylitol has indicated dental health benefits in caries prevention, showing superior performance to other polyols (polyalcohols). This is because the structure of xylitol contains a tridentate ligand, (H-C-OH)3 that can rearrange with polyvalent cations like Ca++. This interaction allows for Ca++ to be transported through the gut wall barrier and through saliva may remineralize enamel before dental caries forms.[13]
Early studies from Finland in the 1970s found that a group chewing sucrose gum had 2.92 decayed, missing, or filled (dmf) teeth compared to 1.04 in the group chewing xylitol gums.[14] Recent research[15] confirms a plaque-reducing effect and suggests the compound, having some chemical properties similar to sucrose, attracts and then "starves" harmful micro-organisms, allowing the mouth to remineralize damaged teeth with less interruption. (However, this same effect also interferes with yeast micro-organisms and others, so xylitol is inappropriate for making yeast-based bread, for instance.) This is because cariogenic bacteria prefer fermentable six-carbon sugars, or disacharrides such as sucrose, as opposed to the nonfermentable xylitol, whose antimicrobial properties then "starve" the bacteria, reducing their growth and reproduction.[16] Most of these studies suggest that at least 6 grams of xylitol per day is needed for dental efficacy; for most chewing gum or breath mints this would require 12 pieces per day (op cit).
Xylitol is specific in its inhibition of the mutans streptococci group, bacteria that are significant contributors to tooth decay.[17] Xylitol inhibits mutans streptococci in the presence of other sugars, with the exception of fructose.[18] Daily doses of xylitol below 3.44 grams are ineffective, and doses above 10.32 grams show no additional benefit.[17]
Saliva containing xylitol is more alkaline than saliva which contains other sugar products. After taking xylitol products, the concentration of basic amino acids in saliva may rise. When saliva is alkaline (i.e., its pH is above 7), calcium and phosphate salts in saliva start to precipitate into those parts of enamel where they are lacking.[19][20]
Xylitol also inhibits the growth of Streptococcus pneumoniae, as well as the attachment of Haemophilus influenzae on the nasopharyngeal cells, making xylitol nose spray a very marketable product.[13]
Xylitol-based products are allowed by the U.S. Food and Drug Administration to make the medical claim that they do not promote dental cavities.[21]
A recent study demonstrated, as a water additive for cats, xylitol was effective in reducing plaque and calculus accumulation.[22] However, there is evidence xylitol may be dangerous to dogs.
Possessing approximately 40% less food energy,[23] xylitol is a low-calorie alternative to table sugar. Absorbed more slowly than sugar, it does not contribute to high blood sugar levels or the resulting hyperglycemia caused by insufficient insulin response. This characteristic has also proven beneficial for people suffering from metabolic syndrome, a common disorder that includes insulin resistance, hypertension, hypercholesterolemia, and an increased risk for blood clots.[24]
Xylitol also has potential as a treatment for osteoporosis. A group of Finnish researchers has found dietary xylitol prevents weakening of bones in laboratory rats, and actually improves bone density.[25][26]
Studies have shown xylitol chewing gum can help prevent ear infections[27] (acute otitis media); the act of chewing and swallowing assists with the disposal of earwax and clearing the middle ear, while the presence of xylitol prevents the growth of bacteria in the eustachian tubes (auditory or pharyngotympanic tubes) which connect the nose and ear.[28] When bacteria enter the body, they adhere to the tissues using a variety of sugar complexes. The open nature of xylitol and its ability to form many different sugar-like structures appears to interfere with the ability of many bacteria to adhere.[29] In a double-blind, randomized, controlled trial, saline solutions of xylitol significantly reduced the number of nasal coagulase-negative Staphylococcus bacteria. The researchers attributed the benefits to the increased effectiveness of endogenous (naturally present in the body) antimicrobial factors.[30] In a small clinical trial nasally administered xylitol reduced ear complaints in children previously having chronic complaints, on the order of almost one a month, by more than 92%. The author also reported beneficial effects on asthma with nasal administration.[31]
In rats, xylitol has been found to increase the activity of neutrophils, the white blood cells involved in fighting many bacteria. This effect seems to be quite broad, acting even in cases such as general sepsis.[32]
A recent report suggests consumption of xylitol may help control oral infections of Candida yeast; in contrast, galactose, glucose, and sucrose may increase proliferation.[33]
Xylitol has no known toxicity in humans. In one study, the participants consumed a diet containing a monthly average of 1.5 kg of xylitol with a maximum daily intake of 430 g with no apparent ill effects.[34] Like most sugar alcohols, it has a laxative effect because sugar alcohols are not fully broken down during digestion; albeit one-tenth the strength of sorbitol. The effect depends upon the individual. In one study of 13 children, four experienced diarrhea when consuming over 65 grams per day.[5] Studies have reported adaptation occurs after several weeks of consumption.[5]
Dogs that have ingested foods containing high levels of xylitol (greater than 100 milligrams of xylitol consumed per kilogram of bodyweight) have presented with low blood sugar (hypoglycemia), which can be life-threatening.[35] Low blood sugar can result in a loss of coordination, depression, collapse and seizures in as soon as 30 minutes.[36][37] Intake of very high doses of xylitol (greater than 500 – 1000 mg/kg bwt) has also been implicated in liver failure in dogs, which can be fatal.[38] These are points of controversy, however, as earlier World Health Organization studies using much higher doses on dogs for long periods showed no ill effect.[39] A study published in the Journal of Veterinary Pharmacology and Therapeutics involved two groups of eight Pekingese dogs fed either 1 or 4 g/kg of xylitol. In addition to developing hypoglycemia, all of the dogs developed elevated levels of liver enzymes associated with liver damage. The dogs also developed reduced serum phosphorus and potassium, and increased serum calcium.[40]
|
|||||