Tagatose (D-tagatose)

Q: What is tagatose?

A rare sugar related to fructose that is only partly absorbed. It is used as a low-calorie sweetener, about 75 to 92% as sweet as table sugar.

Q: Does tagatose lower blood sugar?

After one 5 g drink it lowered 2-hour glucose in adults with raised fasting glucose or type 2 diabetes, not in adults with normal glucose. The evidence is a single small crossover trial.

Q: Is tagatose safe for the liver?

In 12 healthy men, 45 g a day for 28 days did not change liver volume, liver glycogen, liver enzymes or uric acid.

Q: Why does tagatose cause gas and diarrhoea?

Part of each dose is not absorbed. It holds water in the gut and is fermented in the colon, so doses around 29 to 30 g often caused bloating, flatulence and loose stools.

Q: Is tagatose regulated as safe?

FDA has had no questions on two GRAS notices (2001 and 2021), JECFA allocated an ADI "not specified", and it is an authorised novel food in Great Britain with a laxative-effect label statement above 15 g per serving.

Q: Does tagatose help teeth?

A small trial found S. mutans fell only when chewing gum contained both tagatose and xylitol; neither alone reduced bacteria. The study had 19 volunteers.

Also called D-tagatose, D-tagatose sweetener, Naturlose, tagatose sugar substitute, rare sugar tagatose.

Best grade C across 4 graded outcomes Other Last checked Oct 25, 2026

The short answer

From 12 sources

Tagatose is a poorly absorbed sugar sold as a sweetener. Small trials found a single 5 g dose lowered post-drink glucose in people with raised blood sugar, and 45 g a day for 28 days did not enlarge the liver. At about 29 g in one go, bloating, gas and diarrhoea are common.

Every graded outcome on this page

4 rows · line = participants

Grade CBlood glucose and insulin after a single drinkBlood sugarn 85
Grade DFood intake after a single doseAppetiten 19
Grade DLiver volume and glycogen (safety)Liver safetyn 12
Grade DWeight, HbA1c and HDL in type 2 diabetesWeight and lipidsn 8

Key facts

What it is: Rare sugar related to fructose; poorly absorbed in the small intestine and fermented in the colon^9,10
Blood sugar: A single 5 g dose lowered 2-hour glucose and glucose AUC in 33 adults with raised fasting glucose or type 2 diabetes, but not in 52 with normal glucose⁵
Gut effects: At 29 to 30 g in one dose, nausea (15.1%) and diarrhoea (31.5%) were reported in a 73-man screening study; flatulence was common^9,10
Liver safety: 45 g/day for 28 days in 12 men produced no change in liver volume or glycogen⁷
Regulatory: FDA has had no questions on GRAS notices GRN 78 (2001) and GRN 977 (2021); JECFA allocated an ADI "not specified"^1,2,3

What it is

Tagatose is a rare sugar, a sibling of fructose, made from lactose or by enzymes and used as a low-calorie sweetener about 75 to 92% as sweet as table sugar.

How it works

Established

Tagatose is only partly absorbed in the small intestine. The unabsorbed portion draws water into the gut and is fermented in the large intestine, which explains the gas, distension and loose stools seen at higher doses. Effects on blood glucose in the trials are small and appear in people with raised glucose.^5,9,10

Forms

Form

The form on this page
Form	Elemental %	Absorption (human data)	GI tolerance	Studied for
Tagatose powder or sweetener packets	Varies¹⁰Not applicable (sugar; labelled by grams per serving)	Poorly absorbed in the small intestine; the remainder is fermented in the colon.¹⁰	Dose-related nausea, bloating, flatulence and loose stools; most symptoms were light or moderate in a single 29 g dose study.^9,10	Post-drink glucose (5 to 10 g single doses), tolerance (29 to 30 g single doses), and 45 g/day for 28 days to 12 months

What the human research says

Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.

Trial map

4 graded outcomes, largest study first

4 graded outcomes: 3 mixed, 1 no effect. The largest, a 2013 crossover trial of 85 people on blood glucose and insulin after a single drink, found mixed results.

By sizeTable

1Blood glucose and insulin after a single drink

Mixed · Grade C · Crossover RCT, 85 people, 2013

Korean adults: 52 with normal glucose and 33 with impaired fasting glucose or newly diagnosed type 2 diabetes

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Blood glucose and insulin after a single drink	Mixed	85	Grade C · Crossover RCT, 2013	Korean adults: 52 with normal glucose and 33 with impaired fasting glucose or newly diagnosed type 2 diabetes
Food intake after a single dose	Mixed	19	Grade D · Crossover RCT, 2000	19 normal-weight men
Liver volume and glycogen (safety)	No effect	12	Grade D · Crossover RCT, 2001	12 healthy men
Weight, HbA1c and HDL in type 2 diabetes	Mixed	8	Grade D · Open-label trial, 2010	Adults with type 2 diabetes (pilot; 12 recruited, 8 analysed)

Every graded row

4 rows

Showing 4 of 4 outcomes. Human trials only.

Grade CBlood glucose and insulin after a single drinkBlood sugarLower post-drink glucose in the hyperglycaemic group onlyCrossover RCT
n 85 · 2013

Mixed With 5 g, the hyperglycaemic group had lower glucose at 120 min (p = 0.019) and lower glucose AUC (p = 0.017); the normal group did not. With 10 g, normal-glucose adults had lower insulin at 30 and 60 min and lower insulin and C-peptide AUC. Age-matched groups responded similarly.

Design: Crossover RCT, n = 85, 2013
Population: Korean adults: 52 with normal glucose and 33 with impaired fasting glucose or newly diagnosed type 2 diabetes
Form: D-tagatose
Dose: 5 g (hyperglycaemic group); 10 g (normal group, high dose)
Duration: Single dose per arm, 7 days apart
Source: Reference 5 · PubMed 23760573 (opens PubMed)

Grade DFood intake after a single doseAppetite15% lower intake at one late meal onlyCrossover RCT
n 19 · 2000

Mixed Energy intake at lunch and in the snacking period was similar to sucrose; at the supper buffet 9 h later it was 15% lower (P < 0.05). The authors link this to gut distension from unabsorbed tagatose.

Design: Crossover RCT, n = 19, 2000
Population: 19 normal-weight men
Form: D-tagatose
Dose: 29 g in a breakfast meal (replacing 29 g sucrose)
Duration: Single meal
Source: Reference 8 · PubMed 11029974 (opens PubMed)

Grade DLiver volume and glycogen (safety)Liver safetyNo change in liver size or glycogen at 45 g/day for 28 daysCrossover RCT
n 12 · 2001

No effect MR imaging and spectroscopy showed no treatment effect on liver volume or liver glycogen. Liver enzymes, uric acid and other clinical chemistry showed no clinically relevant changes.

Design: Crossover RCT, n = 12, 2001
Population: 12 healthy men
Form: D-tagatose
Dose: 15 g three times daily (45 g/day) replacing sucrose
Duration: 28 days per arm
Source: Reference 7 · PubMed 11350207 (opens PubMed)

Grade DWeight, HbA1c and HDL in type 2 diabetesWeight and lipidsWeight and HDL moved in a tiny uncontrolled pilotOpen-label trial
n 8 · 2010

Mixed No serious adverse effects, but 10 of 12 recruited subjects had mild, transient GI side effects. Excluding 3 subjects whose diabetes medicines were changed, weight fell from 108.4 to 103.3 kg (P = 0.001); HbA1c fell non-significantly (10.6% to 9.6%, P = 0.08); HDL rose from 30.5 to 41.7 mg/dL in the 6 without lipid-drug changes.

Design: Open-label trial, n = 8, 2010
Population: Adults with type 2 diabetes (pilot; 12 recruited, 8 analysed)
Form: D-tagatose
Dose: 15 g three times daily with food (45 g/day)
Duration: 12 months after a 2-month run-in
Source: Reference 6 · PubMed 21147362 (opens PubMed)

What the numbers add up to

Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.

Safety was probed hard because rats' livers grew

High-dose tagatose caused reversible liver enlargement in rats, so researchers measured human liver volume and glycogen with MR after 28 days at 45 g a day and found no change.⁷

The weight and HDL data are not strong

The one-year weight and HDL results come from 5 to 6 people after excluding others and had no placebo group, so they are a lead for larger trials, not an effect to expect.⁶

Studied doses

Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.

Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.

Doses studied in human trials

Doses studied in human trials ranged from single doses of 5 to 10 g for blood sugar and 29 to 30 g for tolerance up to 45 g a day (15 g three times daily) for 28 days in healthy men and for 12 months in 8 adults with type 2 diabetes. These are research doses, not advice.^5,6,7,9

Interactions and safety

Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.

What Tagatose meets

2 cited rows

Medicines 1

Tagatose1 medicine · 1 supplement

Supplements and foods 1

Measured in a human study
Reference summary

Interactions

2 agents

Published interactions, grouped by kind
Agent	What the source says	Evidence
Medicines1
Glucose-lowering medicines (insulin, oral agents)	A single 5 g dose lowered post-drink glucose in hyperglycaemic adults. No interaction trial with diabetes medicines was found, so an additive effect cannot be ruled out. In the 12-month pilot, three participants whose diabetes medicines changed were excluded from the weight analysis.^5,6	RCT
Other supplements1
Other poorly absorbed sugars and fibres (sugar alcohols, inulin)	No study tested combinations. Each is fermented or osmotically active in the gut, so stacking them could add to gas and loose stools; this is an inference from the mechanism, not a trial finding.^9,10	Review

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Tagatose and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Tagatose.

Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.

Who should be careful

4 groups

Sensitive digestion: In a double-blind crossover, 29 g of tagatose scored higher than sucrose for rumbling, distension, nausea, flatulence and diarrhoea; two vomiting cases were recorded. The authors judged 30 g in one dose above what should be used for ordinary use.^9,10
Diabetes on glucose-lowering medicines: Tagatose lowered glucose after a drink in hyperglycaemic adults. Anyone on insulin or other glucose-lowering drugs should ask their prescriber before regular use, since interaction trials are missing.^5,6
Pregnancy, breastfeeding and children: No human trials in these groups were found in the sources reviewed, so the safety of regular supplemental intake is unknown.¹⁰
Labelling in Great Britain: UK authorisation requires the wording "excessive consumption may produce laxative effects" on foods above 15 g per serving and on beverages above 1% tagatose.⁴

How to read the label

What to check on the Supplement Facts panel.

How to read the label

2 checks

Count grams per serving

Tagatose is sold as a sweetener, so the label usually lists grams per serving. The blood sugar result came from 5 g; gut symptoms were reported at 29 to 30 g.^5,9

Watch for blends

Many sweeteners combine tagatose with other sugars or sugar alcohols. The trials here used tagatose alone, so their results do not carry over to blends.^5,7

Label X-RayPhotograph a bottle's Supplement Facts panel and see each line, tagatose (D-tagatose) included, beside the doses and forms the trials used

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

6 answers

What is tagatose?

A rare sugar related to fructose that is only partly absorbed. It is used as a low-calorie sweetener, about 75 to 92% as sweet as table sugar.^10,12

Does tagatose lower blood sugar?

After one 5 g drink it lowered 2-hour glucose in adults with raised fasting glucose or type 2 diabetes, not in adults with normal glucose. The evidence is a single small crossover trial.⁵

Is tagatose safe for the liver?

In 12 healthy men, 45 g a day for 28 days did not change liver volume, liver glycogen, liver enzymes or uric acid.⁷

Why does tagatose cause gas and diarrhoea?

Part of each dose is not absorbed. It holds water in the gut and is fermented in the colon, so doses around 29 to 30 g often caused bloating, flatulence and loose stools.^9,10

Is tagatose regulated as safe?

FDA has had no questions on two GRAS notices (2001 and 2021), JECFA allocated an ADI "not specified", and it is an authorised novel food in Great Britain with a laxative-effect label statement above 15 g per serving.^1,2,3,4

Does tagatose help teeth?

A small trial found S. mutans fell only when chewing gum contained both tagatose and xylitol; neither alone reduced bacteria. The study had 19 volunteers.¹¹

Sources

12 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

12 sources

1GRAS Notice GRN No. 78: D-Tagatose (FDA response: no questions, closed Oct 25, 2001)Database U.S. Food and Drug Administration, 2001 · hfpappexternal.fda.gov
2GRAS Notice GRN No. 977: D-tagatose produced via novel enzymatic cascade (FDA: no questions, closed Oct 21, 2021)Database U.S. Food and Drug Administration, 2021 · hfpappexternal.fda.gov
3D-tagatose: JECFA evaluation (ADI "not specified")Database WHO/FAO JECFA Food Additives database, 2004 · apps.who.int
4Authorised novel food NOVEL-40: D-Tagatose (Great Britain)Database UK Food Standards Agency, 2025 · data.food.gov.uk
5Beneficial effect of tagatose consumption on postprandial hyperglycemia in Koreans: a double-blind crossover designed study.Crossover RCT Food Funct, 2013 · PMID 23760573
6Dietary supplementation with d-tagatose in subjects with type 2 diabetes leads to weight loss and raises high-density lipoprotein cholesterol.Open-label trial Nutr Res, 2010 · PMID 21147362
7Effect of oral D-tagatose on liver volume and hepatic glycogen accumulation in healthy male volunteers.Crossover RCT Regul Toxicol Pharmacol, 2001 · PMID 11350207
8The acute effect of D-tagatose on food intake in human subjects.Crossover RCT Br J Nutr, 2000 · PMID 11029974
9Human tolerance to a single, high dose of D-tagatose.Crossover RCT Regul Toxicol Pharmacol, 1999 · PMID 10341163
10Human gastrointestinal tolerance to D-tagatose.Observational Regul Toxicol Pharmacol, 1999 · PMID 10341164
12Assessment of the Novel Food D-tagatose for a Change to the Conditions of Use (RP1652)Review UK Food Standards Agency, 2025 · science.food.gov.uk
11D-Tagatose Effectively Reduces the Number of Streptococcus mutans and Oral Bacteria in Healthy Adult Subjects: A Chewing Gum Pilot Study and Randomized Clinical Trial.RCT Acta Med Okayama, 2020 · PMID 32843762

What changed

Every dated change to this page: what changed, who made it and why.

Change log

2 entries

Dated changes to this page
Date	Change	Who and why
Oct 25, 2026evidence	Adversarial review: 12-man liver MR crossover regraded no-effect to D (too small to show no effect). Other rows match their abstracts; FDA GRAS records GRN 78 and GRN 977, the JECFA entry (ADI not specified, 2004) and the FSA NOVEL-40 labelling condition re-opened and confirmed.	Writer: Kymata Health EditorialTrigger: adversarial review
Oct 15, 2026all	Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal) and each cited abstract read; figures taken from the abstracts. Regulatory status from the FDA GRAS inventory (GRN 78, GRN 977), the WHO/FAO JECFA database and the UK FSA novel food register.	Writer: Kymata Health EditorialTrigger: new page

Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.

Tagatose (D-tagatose)

Medicines 1

Supplements and foods 1

Glucose-lowering medicines (insulin, oral agents)

Other poorly absorbed sugars and fibres (sugar alcohols, inulin)