Xylitol is a chemical categorized as a polyalcohol or sugar alcohol. Xylitol has the formula3(CH2OH)2
and is an achiral isomer of pentane-1,2,3,4,5-pentol. Xylitol is used as a diabetic sweetener which
is roughly as sweet as sucrose with 33% fewer calories. Unlike other natural or synthetic
sweeteners, xylitol is actively beneficial for dental health by reducing caries to a
third in regular use and helpful to remineralization. Multiple studies utilizing electron microscopy
have indicated that xylitol is effective in inducing remineralization of deeper layers
of demineralized enamel. Fair evidence was found that xylitol reduced the incidence of
acute middle ear infection in healthy children. Xylitol is naturally found in low concentrations
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,
and birch. However, industrial production starts from xylan extracted from hardwoods
or corncobs, which is hydrolyzed into xylose and catalytically hydrogenated into xylitol.
A study in rats found that xylitol had reduced or nonexistent side effects compared to other
artificial sweeteners, and lower caloric value and cariogenicity than sucrose.
Production 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 that would not affect insulin levels of people with diabetes.
Xylitol is produced by hydrogenation of xylose, which converts the sugar into a primary alcohol.
It can also be extracted from natural sources, and is often harvested by tapping birch trees
to produce birch sap. Another method of producing xylitol is through microbial processes, including
fermentative and biocatalytic processes in bacteria, fungi, and yeast cells, that take
advantage of the xylose-intermediate fermentations to produce high yield of xylitol. Common yeast
cells used in effectly fermenting and producing xylitol are Candida tropicalis and Candida
guilliermondii. Its dental significance was researched in Finland in the early 1970s.
There, scientists at Turku University demonstrated dental benefits in what became known as the
"Turku sugar studies". Properties
One gram of xylitol contains 2.4 kilocalories, as compared to one gram of sugar, which has
3.87 kcal. Xylitol has virtually no aftertaste, and is advertised as "safe for diabetics and
individuals with hyperglycemia." This tolerance is attributed to the lower effect of xylitol
on a person's blood sugar, compared to that of regular sugars as it has an extremely low
glycemic index of 7. Xylitol has no known toxicity or carcinogenicity, and is considered
safe by the U.S. FDA Health benefits
Dental care Xylitol is a “tooth-friendly”, nonfermentable
sugar alcohol. It appears to have more dental health benefits than other polyalcohols. The
structure of xylitol contains a tridentate ligand,3 that can rearrange with polyvalent
cations like Ca2+. This interaction allows Ca2+ to be transported through the gut wall
barrier and through saliva may remineralize enamel before dental caries form.
Early studies from Finland in the 1970s found compared to chewing sucrose-flavored gum,
xylitol resulted in nearly two fewer cavities or missing teeth. Cavity-causing bacteria
prefer six-carbon sugars or disaccharides, while xylitol is non-fermentable and cannot
be used as an energy source - while still being taken up into the cell and leaving no
room for the six-carbon sugars, interfering with bacterial growth and reproduction. The
harmful micro-organisms are starved in the presence of xylitol, allowing the mouth to
remineralize damaged teeth with less interruption. This same property renders it unsuitable for
making bread as it interferes with the ability of yeast to digest sugars. At least six grams
of xylitol per day is thought to be needed for dental efficacy.
Xylitol also inhibits the growth of Streptococcus pneumoniae, as well as the attachment of Haemophilus
influenzae on the nasopharyngeal cells. The perception of sweetness obtained from
consuming xylitol initiates the body to secrete saliva that acts as a buffer system against
the acidic environment created by the microorganisms in the dental plaque. Increase in salivary
pH can raise the falling pH to its neutral pH within few minutes of xylitol consumption.
However, despite these promising conjectures two systematic reviews of clinical trials
could not find conclusive evidence that xylitol was indeed superior to other polyols such
as sorbitol or equal to that of topical fluoride in its anti-caries effect.
In the 33-month Xylitol for Adult Caries Trial, participants were given lozenges of either
five grams of xylitol or a sucralose-sweetened placebo. While this study initially found
no statistically significant reduction in 33-month caries increment among adults at
an elevated risk of developing caries, a further examination of data from this study revealed
a significant reduction in the incidence of root caries in the group that received xylitol.
Xylitol is categorized by the U.S. Food and Drug Administration as a food additive. Like
other sugar alcohol-sweetened products, xylitol-sweetened products are allowed to be labeled with the
claim that they do not promote dental cavities. Diabetes
Possessing approximately 33% fewer calories, xylitol is a lower-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. Xylitol is used as a sweetener in medicines, chewing gum and pastilles.
Source of energy Xylitol consumed is absorbed incompletely
and some that are unabsorbed can be used as a dietary fiber in helping to maintain gut
function that consequently uses bacterial fermentation to convert xylitol to short fatty
acid chains that can be utilized in energy pathways. Xylitol is also useful in recovery
after heavy exercise because of its ability to efficiently convert to glucose and glycogen.
Ear infection Xylitol chewing gum appears to decrease rates
of acute otitis media in children going to daycare by 25%. Xylitol nasal sprays have
also been shown to decrease incidence of acute otitis media as well as being a very effective
way of both assisting and stimulating the body’s own natural nasopharyngeal washing,
and reducing both bacterial colonization and allergenic pollution, with their accompanying
problems. Safety
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. 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. Studies have reported adaptation occurs
after several weeks of consumption. As with other sugar alcohols, with the exception
of erythritol, consumption in excess of one's laxation threshold 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. Xylitol toxicity in dogs
Xylitol is well established as a life-threatening toxin to dogs. According to the ASPCA Animal
Poison Control Center, the number of cases of xylitol toxicosis in dogs has significantly
increased since the first reports in 2002. Dogs that have ingested foods containing xylitol
have presented with low blood sugar, which can be life-threatening. Low blood sugar can
result in a loss of coordination, depression, collapse and seizures in as little as 30 minutes.
Intake of doses of xylitol has been implicated in liver failure in dogs, which can be fatal.
Possible cause of hypoglycemia experienced by dogs is the fact that the xylitol in gum
is released more slowly and absorbed over longer period than when it is consumed as
a pure form. See also
Aspartame L-xylulose reductase
Sucralose Xylonic acid
Birch sap Notes and references