Xylitol
A naturally occurring sugar alcohol used as a reduced-calorie sweetener. Causes digestive upset in larger amounts.
At higher intakes xylitol draws water into the gut and acts as a laxative, causing bloating, cramps and diarrhoea. UK law requires a laxative-effect warning on foods where polyols exceed 10% of the product.
What is it?
Xylitol is a five-carbon sugar alcohol (polyol) found naturally in small amounts in many fruits and vegetables, and produced commercially by hydrogenating xylose derived from hardwood or corncob hemicellulose. It looks and tastes like sugar but has about 40% fewer calories (2.4 kcal per gram versus 4 kcal for sugar).
What does it do?
Xylitol sweetens food without causing the sharp blood-glucose spike that sucrose does, because it is absorbed slowly and only partly metabolised through a non-insulin-dependent pathway in the liver. It also inhibits the acid production of Streptococcus mutans bacteria in the mouth, which is the basis for its dental-health claims in chewing gum. As a polyol it also holds moisture, functioning as a humectant in confectionery and baked goods.
Where you will see it
Most commonly found in sugar-free chewing gum, mints, and throat lozenges. Also appears in diabetic confectionery, low-sugar sweets, sugar-free chocolate, some toothpaste and mouthwash, protein bars, and low-carbohydrate baked goods. On a UK label it appears as 'xylitol' or 'E967'. Products where polyols exceed 10% must carry the warning 'excessive consumption may cause laxative effects'.
What the science says
Laxative effect at higher doses
Like all polyols, xylitol is not fully absorbed in the small intestine. Unabsorbed xylitol passes to the large intestine where it draws water osmotically and is fermented by gut bacteria, producing gas and loose stools. The threshold at which this occurs varies between individuals, but clinical studies have documented diarrhoea at single intakes of roughly 40 to 50 grams in adults. Lower amounts, around 15 to 30 grams spread through the day, commonly cause bloating and discomfort. Regular small intakes can increase tolerance as gut bacteria adapt.
Single oral doses of xylitol above approximately 40 to 50 grams caused diarrhoea in adult volunteers in dose-escalation studies; lower doses produced bloating and flatulence.
EU Regulation 1169/2011 (food information to consumers) requires foods containing more than 10% added polyols to carry the on-pack statement: 'excessive consumption may cause laxative effects'.
Dental health benefit
EFSA evaluated xylitol in chewing gum and concluded that it contributes to maintaining tooth mineralisation by reducing the acid-producing activity of decay-causing bacteria in dental plaque. This is one of the few additive-related health claims that has survived EU scrutiny and is permitted on product labels. The effect requires meaningful frequency of use (several pieces of gum per day after meals), not trace dietary exposure.
EFSA's Panel on Dietetic Products, Nutrition and Allergies authorised the claim that xylitol in chewing gum 'contributes to the maintenance of tooth mineralisation' under Regulation (EC) No 1924/2006.
Blood glucose and insulin response
Xylitol has a glycaemic index of around 7 to 13, compared with approximately 65 for sucrose, meaning it produces a much smaller rise in blood glucose after eating. Insulin response is also substantially lower. This was the original reason it was introduced as a sweetener for diabetic foods in the mid-twentieth century. However, it still provides calories and still raises blood glucose to some degree; it is not calorie-free or glucose-neutral.
Xylitol consumed in place of sucrose produced a significantly lower postprandial blood glucose and insulin response in human trials.
Severe toxicity in dogs
Xylitol is acutely toxic to dogs. Even small amounts (a piece or two of gum) can trigger a rapid, life-threatening drop in blood glucose (hypoglycaemia) and, at higher doses, acute liver failure. The mechanism differs from human metabolism: in dogs, xylitol triggers a large insulin release from the pancreas. This is not a human health concern but is directly relevant to households where gum, mints, or low-sugar baked goods containing xylitol are accessible to pets.
Xylitol ingestion in dogs causes dose-dependent hypoglycaemia and hepatic necrosis; cases of fatal acute liver failure have been reported following ingestion of xylitol-containing food products.
Where it stands with the regulators
Who should be careful
People with irritable bowel syndrome (IBS) or other functional gut conditions are particularly sensitive to polyols and may experience symptoms at lower doses than the general population; xylitol is one of the fermentable carbohydrates targeted by the low-FODMAP diet. Anyone with fructose malabsorption should also be cautious. Dog owners should treat any xylitol-containing product as a serious pet hazard and store it out of reach. Look for 'xylitol' or 'E967' in the ingredients list.
The honest read
Xylitol's main real-world issue for people is straightforward: eat enough of it and you will get diarrhoea. The dose at which this happens varies between individuals, and regular low-level exposure can increase tolerance, but the effect is well established and is the reason UK law mandates the on-pack warning. There is no IARC carcinogen classification, no EU or UK ban, and no endocrine-disruption signal. The dental benefit claim is one of the few additive-related health claims to survive EU regulatory scrutiny. The science here is not unsettled so much as dose-dependent: small amounts in a piece of gum are handled differently from several pieces of a protein bar.
Related additives
Common questions
Is E967 banned in the UK?
No. Xylitol (E967) is an approved food additive in the UK and EU, listed on the UK FSA's approved-additives register. It is widely used in sugar-free chewing gum, mints, and confectionery.
Does xylitol cause diarrhoea?
Yes, at higher doses. Xylitol is only partially absorbed in the gut; the portion that reaches the large intestine draws in water and is fermented by bacteria, producing gas and loose stools. Adults typically notice effects above roughly 15 to 30 grams spread through a day, with more pronounced diarrhoea at 40 grams or more. UK law requires products where polyols exceed 10% of the product to carry the warning 'excessive consumption may cause laxative effects'.
What foods contain E967?
Sugar-free chewing gum and mints are the most common sources. Xylitol also appears in diabetic sweets and chocolate, some protein bars and snack products, throat lozenges, low-carbohydrate baked goods, and some toothpastes and mouthwashes. Check the ingredients list for 'xylitol' or 'E967'.
Is E967 vegan?
Yes. Xylitol is produced from plant material, typically hardwood (birch) or corncob fibre, through a hydrogenation process that does not use any animal-derived ingredients. It is considered vegan by mainstream vegan standards.
Sources
- UK FSA regulated products register: E-967 Xylitol
- EU Regulation 1333/2008 on food additives (Annex II, sweeteners)
- Commission Regulation (EU) No 1129/2011 establishing Annex II of Regulation 1333/2008 (food additive Union list including polyols Group IV)
- EU Regulation 1169/2011 on food information to consumers (Annex III, polyol warning)
- EFSA NDA Panel opinion: authorisation of the health claim for xylitol in chewing gum and tooth mineralisation
- Makinen KK, Dietary prevention of dental caries and associated polyol-induced diarrhoea, Digestive Diseases and Sciences
- Dunayer EK & Gwaltney-Brant SM, Acute hepatic failure and hypoglycaemia in dogs following xylitol ingestion, Veterinary and Human Toxicology
- Ly KA et al., The case for xylitol as a preventive agent in dental caries: an overview, Journal of the American Dental Association
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