# Lactitol
**Lactitol** (4-O-β-D-galactopyranosyl-D-glucitol) is a disaccharide sugar alcohol, or polyol, produced by the catalytic hydrogenation of lactose and used as a bulk sweetener in reduced-calorie foods and as an osmotic laxative.[1](https://pubchem.ncbi.nlm.nih.gov/compound/Lactitol) It is not found in nature.[2](https://www.sciencedirect.com/science/article/pii/S0924224418306940) In the European Union it is the food additive E 966, and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) lists it under INS 966 with an acceptable daily intake of "not specified", a designation reserved for substances of very low toxicity.[3](https://www.efsa.europa.eu/en/topics/topic/sweeteners) • [4](https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/3084) In the United States, the oral lactitol product Pizensy was approved by the FDA in February 2020 for chronic idiopathic constipation in adults.[1](https://pubchem.ncbi.nlm.nih.gov/compound/Lactitol)
| Key fact | Detail |
|---|---|
| Chemical identity | 4-O-β-D-galactopyranosyl-D-glucitol; formula C12H24O11; molecular weight 344.31 g/mol; CAS 585-86-4[1](https://pubchem.ncbi.nlm.nih.gov/compound/Lactitol) |
| Production | Catalytic hydrogenation of lactose over Raney nickel; industrial runs use 30–50 wt% lactose solution at 70–130 °C and 30–75 bar hydrogen[5](https://pubchem.ncbi.nlm.nih.gov/compound/585-86-4) |
| Sweetness and calories | 30–40% as sweet as sucrose; 2.0 kcal/g for US nutrition labeling[6](https://www.law.cornell.edu/cfr/text/21/101.9) • [7](https://link.springer.com/article/10.1007/s00217-015-2437-7) |
| Digestion | Not hydrolyzed or absorbed in the small intestine for lack of a suitable β-galactosidase; fermented by colonic bacteria[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC6363527/) |
| Drug use | Pizensy, an osmotic laxative for chronic idiopathic constipation in adults, 20 g once daily, FDA-approved 2020[9](https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/211281s001lbl.pdf) |
| Safety evaluation | JECFA ADI "not specified" (1983 evaluation); EFSA re-evaluation of E 966 ongoing[4](https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/3084) • [3](https://www.efsa.europa.eu/en/topics/topic/sweeteners) |
| Physical form | White crystalline powder (anhydrous, monohydrate, or dihydrate); melting point 146 °C; non-hygroscopic[1](https://pubchem.ncbi.nlm.nih.gov/compound/Lactitol) • [7](https://link.springer.com/article/10.1007/s00217-015-2437-7) |
## Chemistry and production
Lactitol consists of a galactose unit glycosidically linked to sorbitol (D-glucitol), the glucose portion of lactose having been reduced during hydrogenation.[10](https://ewpa.euromilk.org/wp-content/uploads/2024/05/Lactose_Dairy_Ingredient_Application_Guide.pdf) The industrial process hydrogenates an aqueous lactose solution over a [Raney nickel](https://www.edgepedia.org/raney-nickel) catalyst; after filtration, ion exchange, and concentration, crystallization conditions determine whether the anhydrous, monohydrate, or dihydrate form is obtained, with the anhydrous form favored at higher temperatures.[5](https://pubchem.ncbi.nlm.nih.gov/compound/585-86-4) In laboratory studies over molybdenum-promoted sponge nickel catalysts, lactitol selectivity ranged from 90 to 99%, improving with higher hydrogen pressure and lower temperature.[11](https://doi.org/10.1021/ie0601899)
The compound was discovered in 1920 by a French food chemist but was not used commercially until the 1980s.[7](https://link.springer.com/article/10.1007/s00217-015-2437-7) JECFA specifications prepared in 1996 require an assay of 95.0–102.0% on the anhydrous basis and limit nickel residue to 2 mg/kg, reflecting the catalyst used in manufacture.[12](https://www.fao.org/fileadmin/user_upload/jecfa_additives/docs/Monograph1/Additive-249.pdf)
## Sweetener properties
Lactitol tastes clean and sweet at 30–40% of the sweetness of sucrose, so it is usually combined with intense sweeteners such as acesulfame K, aspartame, or sucralose when used in foods.[7](https://link.springer.com/article/10.1007/s00217-015-2437-7) • [8](https://pmc.ncbi.nlm.nih.gov/articles/PMC6363527/) For US nutrition labeling, FDA regulations assign it a caloric value of 2.0 calories per gram, compared with 4 kcal/g for conventional carbohydrate.[6](https://www.law.cornell.edu/cfr/text/21/101.9) It has a negligible effect on blood glucose and can be metabolized without insulin, and it does not take part in Maillard browning reactions, which supports long storage.[7](https://link.springer.com/article/10.1007/s00217-015-2437-7)
**Food applications.** Because it is non-hygroscopic and dissolves readily, lactitol is used as a sucrose replacer in sugar-free chocolate, candies, baked goods, ice cream, chewing gum, and reduced-sugar preserves.[7](https://link.springer.com/article/10.1007/s00217-015-2437-7) Under 21 CFR 101.80, foods sweetened with lactitol are eligible for a US health claim that they do not promote tooth decay, because oral bacteria cannot readily ferment it; a 1989 review found its enamel-demineralizing potential and plaque formation in humans substantially lower than sucrose's.[13](https://www.law.cornell.edu/cfr/text/21/101.80) • [14](https://pubmed.ncbi.nlm.nih.gov/2649439/)
## Fate in the gut
Human digestive enzymes do not hydrolyze lactitol, and it is normally not absorbed in the small intestine because no suitable β-galactosidase is present; it therefore reaches the colon, where bacteria ferment it.[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC6363527/) A radiolabel study in six volunteers given 20 g daily found 62.9% of the isotope recovered as breath 14CO2, indicating extensive colonic metabolism, with about 54.5% of the theoretical energy content utilized.[15](https://pmc.ncbi.nlm.nih.gov/articles/PMC1434111/?page=0) [Fermentation](https://www.edgepedia.org/fermentation) lowers colonic pH, promotes bifidobacteria and lactobacilli, and decreases counts of proteolytic bacteria such as [Bacteroides](https://www.edgepedia.org/bacteroides), coliforms, and Enterococci, which underlies its description as a prebiotic.[8](https://pmc.ncbi.nlm.nih.gov/articles/PMC6363527/)
The same fermentation and osmotic activity produce its side effects. Higher intakes cause flatulence, osmotic diarrhea, and gastrointestinal discomfort; a meta-analysis found lactitol generally well tolerated up to 40 g per day, with only 5% of constipation patients discontinuing because of gastrointestinal symptoms.[16](https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/lactitol) • [17](https://pmc.ncbi.nlm.nih.gov/articles/PMC4103919/) As a disaccharide polyol it is generally better tolerated than the monosaccharide polyol sorbitol, which exerts a greater osmotic load in the colon.[18](https://pmc.ncbi.nlm.nih.gov/articles/PMC5508768/)
## Laxative use
Lactitol acts as an osmotic laxative, drawing water into the small intestine and increasing fecal volume and peristalsis.[19](https://www.drugs.com/pro/pizensy.html) • [17](https://pmc.ncbi.nlm.nih.gov/articles/PMC4103919/) A 2014 systematic review and meta-analysis of adult constipation included eleven studies with 663 patients; lactitol significantly increased weekly stool frequency over baseline (standardized mean difference 1.56, P<0.001) and improved stool consistency, and in randomized trials against lactulose it was slightly more effective on stool frequency (SMD 0.19, P=0.06) with no significant differences in tolerance outcomes.[17](https://pmc.ncbi.nlm.nih.gov/articles/PMC4103919/)
The FDA approved Pizensy (lactitol) for chronic idiopathic constipation in adults in February 2020, at a recommended dose of 20 grams orally once daily, preferably with meals, reducible to 10 grams for persistent loose stools.[1](https://pubchem.ncbi.nlm.nih.gov/compound/Lactitol) • [9](https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/211281s001lbl.pdf) In the pivotal six-month placebo-controlled trial, 25% of lactitol patients met the responder definition versus 13% on placebo, and the lactitol group had a mean increase of 0.8 complete spontaneous bowel movements per week over placebo.[20](https://www.accessdata.fda.gov/drugsatfda_docs/nda/2020/211281Orig1s000MultidisciplineR.pdf) The label lists contraindication in mechanical gastrointestinal obstruction and galactosemia, and advises taking other oral medications at least 2 hours before or after Pizensy because luminal lactitol can reduce their absorption.[9](https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/211281s001lbl.pdf)
## Hepatic encephalopathy
Like lactulose, lactitol is a non-absorbable disaccharide used to reduce intestinal production and absorption of ammonia in hepatic encephalopathy, a neuropsychiatric complication of cirrhosis.[21](https://www.cochrane.org/evidence/CD003044_are-non-absorbable-disaccharides-associated-beneficial-or-harmful-effects-people-cirrhosis-and) A 2016 Cochrane review of 38 randomized trials (1828 participants) found that non-absorbable disaccharides reduced mortality versus placebo or no intervention (RR 0.59, 95% CI 0.40–0.87) and improved hepatic encephalopathy (RR 0.58, 95% CI 0.50–0.69), with moderate-quality evidence, and found no differences between lactulose and lactitol for the remaining outcomes.[22](https://pmc.ncbi.nlm.nih.gov/articles/PMC7004252/) Lactitol was introduced for this indication in the mid-1980s as a second-generation alternative to lactulose, which had entered clinical practice in 1966.[23](https://pmc.ncbi.nlm.nih.gov/articles/PMC5145904/)
## References
1. [Lactitol, PubChem CID 157355](https://pubchem.ncbi.nlm.nih.gov/compound/Lactitol)
2. [Lactitol: Production, properties, and applications, Trends in Food Science & Technology (2019)](https://www.sciencedirect.com/science/article/pii/S0924224418306940)
3. [Sweeteners, EFSA](https://www.efsa.europa.eu/en/topics/topic/sweeteners)
4. [LACTITOL, JECFA database, WHO](https://apps.who.int/food-additives-contaminants-jecfa-database/Home/Chemical/3084)
5. [Lactitol, PubChem CID 157355 (methods of manufacturing section)](https://pubchem.ncbi.nlm.nih.gov/compound/585-86-4)
6. [21 CFR § 101.9, Nutrition labeling of food, Legal Information Institute](https://www.law.cornell.edu/cfr/text/21/101.9)
7. [Sugar alcohols—their role in the modern world of sweeteners: a review, European Food Research and Technology (2016)](https://link.springer.com/article/10.1007/s00217-015-2437-7)
8. [Effects of Sweeteners on the Gut Microbiota: A Review of Experimental Studies and Clinical Trials, Advances in Nutrition (2019)](https://pmc.ncbi.nlm.nih.gov/articles/PMC6363527/)
9. [PIZENSY (lactitol) prescribing information, FDA](https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/211281s001lbl.pdf)
10. [Lactose Derivatives, European Milk Forum ingredient application guide](https://ewpa.euromilk.org/wp-content/uploads/2024/05/Lactose_Dairy_Ingredient_Application_Guide.pdf)
11. [Hydrogenation of Lactose over Sponge Nickel Catalysts: Kinetics and Modeling, Industrial & Engineering Chemistry Research (2006)](https://doi.org/10.1021/ie0601899)
12. [LACTITOL, JECFA monograph, FAO](https://www.fao.org/fileadmin/user_upload/jecfa_additives/docs/Monograph1/Additive-249.pdf)
13. [21 CFR § 101.80, Health claims: dietary noncariogenic carbohydrate sweeteners and dental caries, Legal Information Institute](https://www.law.cornell.edu/cfr/text/21/101.80)
14. [Latest state of research on lactitol and dental caries, International Dental Journal (1989)](https://pubmed.ncbi.nlm.nih.gov/2649439/)
15. [Assimilation of lactitol, an 'unabsorbed' disaccharide in the normal human colon, Gut (1988)](https://pmc.ncbi.nlm.nih.gov/articles/PMC1434111/?page=0)
16. [Lactitol, ScienceDirect Topics overview](https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/lactitol)
17. [Efficacy and tolerance of lactitol supplementation for adult constipation: a systematic review and meta-analysis (2014)](https://pmc.ncbi.nlm.nih.gov/articles/PMC4103919/)
18. [A Systematic Review of the Effects of Polyols on Gastrointestinal Health and Irritable Bowel Syndrome (2017)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5508768/)
19. [Pizensy: Package Insert / Prescribing Information, Drugs.com](https://www.drugs.com/pro/pizensy.html)
20. [NDA Multi-Disciplinary Review and Evaluation, NDA 211281, Pizensy (lactitol), FDA](https://www.accessdata.fda.gov/drugsatfda_docs/nda/2020/211281Orig1s000MultidisciplineR.pdf)
21. [Are non-absorbable disaccharides associated with beneficial or harmful effects in people with cirrhosis and hepatic encephalopathy? Cochrane](https://www.cochrane.org/evidence/CD003044_are-non-absorbable-disaccharides-associated-beneficial-or-harmful-effects-people-cirrhosis-and)
22. [Non-absorbable disaccharides versus placebo/no intervention and lactulose versus lactitol for hepatic encephalopathy, Cochrane Database of Systematic Reviews (2016)](https://pmc.ncbi.nlm.nih.gov/articles/PMC7004252/)
23. [Current state of knowledge of hepatic encephalopathy (part III): non-absorbable disaccharides (2016)](https://pmc.ncbi.nlm.nih.gov/articles/PMC5145904/)
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*Topic: Encyclopedia › Physical world and mathematics › Chemistry › Organic substances › Alcohols, ethers, and organooxygen groups › Alcohols and polyols › Diols and polyols › Sugar alcohols (alditols) › Lactitol*
*Initially written Sep 17, 2026 · Reviewed: Sep 30, 2026; Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
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