D-tagatose is a simple sugar (monosaccharide) that is becoming increasingly established as a brain-friendly sugar alternative in dementia research. In nature, D-tagatose is found in small amounts in apples, oranges, powdered milk, cocoa, cheese, yogurt and other dairy products. Due to its high sweetening power as well as its low calorie content (1.5 to 2 kcal/g) and low influence on blood glucose levels, D-tagatose is present in many diabetic and dietary products. The food industry extracts D-tagatose from the simple sugars galactose (milk sugar) or piscose (mushroom sugar) and uses it in beverages, yogurts, spreads, and confectionery [1, 2]. D-tagatose is now also commercially available, but with a price per kilo of around 180 euros it is still very expensive.

Figure 1: Structure of D-tagatose

The health benefits of D-tagatose are thought to be that it has 80 per cent fewer calories than table sugar, while having a beneficial effect on dental health. Furthermore, numerous studies have shown that D-tagatose has a positive influence on human metabolism. The antidiabetic effect and the positive effects on the microbiome make D-tagatose a fascinating field of research, especially in the context of dementia research.

Blood sugar lowering effect of D-tagatose

There are some studies that investigated the blood glucose-lowering effect of D-tagatose in humans:

  • As early as 1999, a small intervention study found that 75 g of D-tagatose had a glucose-lowering effect in diabetic subjects [3].
  • A cross-sectional study was conducted to investigate the effect of D-tagatose on elevated blood glucose levels after eating, the so-called postprandial glycemic response, in patients who suffered from elevated blood glucose levels (hyperglycemia). The results showed that ingestion of 5 g of D-tagatose significantly lowered blood glucose levels in hyperglycemic patients after 120 minutes. A dose of 10 g of D-tagatose also lowered post-meal serum insulin levels in healthy volunteers. Overall, the results suggest that a drink containing D-tagatose (5g) can control the postprandial glycemic response in patients with elevated blood glucose [2].
  • In another randomized trial with 161 participants, the objective was to assess the safety and effect of (small amounts of) D-tagatose on glycemic control in diabetic patients using “saccharified” hemoglobin (HbA1c level) over a 6-month period. The result was that 5 g of D-tagatose (three times daily) was required to lower HbA1c, whereas an amount of 7.5 g of D-tagatose (three times daily), the highest amount in this study, had a significantly stronger blood glucose-lowering effect [4].
  • The latter studies were continued by investigating the effect of higher doses of D-tagatose in patients with type 2 diabetes. The study divided 480 participants into two groups. 232 received D-tagatose at various doses and 248 formed the placebo group. Daily intake of 15 g of D-tagatose was able to significantly reduce HbA1c levels when taken in 125-250 ml of water three times daily and immediately before meals. The reduction in HbA1c was robust and could be demonstrated in both subgroups, different subpopulations, and with different analytical approaches. D-tagatose also proved to be well tolerated, with only mild side effects occurring in the treatment groups. The authors also emphasized that, unlike many other diabetes medications, the efficacy of D-tagatose increases with duration of use [5].

Antidiabetic effect of D-tagatosis and relevance to dementia.

Exactly how D-tagatose exerts its blood sugar-lowering effect is not yet fully understood. It is discussed that by taking D-tagatose first, other sugars such as glucose (dextrose) are absorbed more slowly by the intestine and released into the blood. The result is a slower rise in blood glucose levels. In addition, D-tagatose inhibits the conversion of glycogen (storage form of glucose) to glucose and promotes the conversion of glucose to glycogen. Through these mechanisms, there is less free glucose in the blood, blood glucose levels remain low, less insulin needs to be secreted, and possible insulin resistance is prevented [2].

This antidiabetic effect is particularly interesting for the prevention of dementia. Alzheimer’s disease is also referred to in professional circles as Type 3 diabetes because there is a direct link between diabetes mellitus and Alzheimer’s disease. The problem with diabetes is the constantly increased glucose concentration in the blood, i.e. elevated blood glucose levels. This is because the body’s own hormone insulin, which is important for utilizing glucose, can no longer work properly. The so-called insulin resistance can also affect the brain and lead to an energy emergency there. If this condition is not treated, it can gradually lead to the failure of certain functions of the nerve cells (neurons). This can eventually lead to the death of brain cells and manifest itself primarily in memory disorders. The insidious onset of Alzheimer’s disease can thus be initiated by diabetes.

D-tagatose would thus be a brain-friendly sugar alternative. The blood sugar-lowering effect could help prevent possible energy crises in the brain as well as inflammation and thus also reduce the risk of dementia.

Prebiotic effect of D-tagatose

After D-tagatose is taken orally, only about 20-25% of it is absorbed in the small intestine, while the rest enters the colon. Here it is converted by intestinal bacteria into short-chain fatty acids (SCFAs) and various gases (1, 8). Short-chain fatty acids such as butyrate have been shown to have several health-promoting effects, including the ability to reduce chronic inflammation, promote neurotransmitter production, activate immune responses, and regulate lipid metabolism. This suggests that they may also have a positive effect on brain health, possibly influencing diseases such as dementia [7].

There are a growing number of studies linking the gut microbiome, its metabolites, and dementia. In this context, people also talk about the Gut-brain axis. In the context of D-tagatose, an in vivo (in the living body) study was conducted to investigate the influence of different types of sugars on the gut microbiome and its metabolites. The subjects, healthy men and women, consumed different breakfasts over a two-week period. In this study, the 30 g raspberry jam was ingested in different variations, either with 7.5 g or 12.5 g of D-tagatose, 7.8 g of fructo-oligosaccharides, 7.6 g of D-tagatose and 7.5 g of fructo-oligosaccharides, or with 15.1 g of sucrose.The results showed that consumption of 7.5 and 12.5 g of D-tagatose led to increased production of short-chain fatty acids such as butyrate and an increase in bacterial Lactobacillus led.

These results suggest that D-tagatose may be useful in promoting the Intestinal Health which in turn could indirectly have positive effects on brain health, including possible dementia prevention [8]. You can also find more information on the topic of “intestinal health” in the corresponding free of charge Fact sheet of Knowledge stops Dementia.


A growing number of studies show that the simple sugar D-tagatose can protect the body from blood sugar spikes, and that it has a beneficial effect on the gut microbiome. These properties may also have a positive impact on brain health, and thus play a role in dementia prevention.

However, research with D-tagatosis in relation to dementia is just getting started. Dementias such as Alzheimer’s are very complex diseases that have a variety of risk factors. For example, neurologist and Alzheimer’s researcher Dr. Dale Bredesen also compares Alzheimer’s disease to a Roof, which can have up to 36 holes, all of which need to be repaired.

Accordingly, we do not see D-tagatosis as a panacea. However, it could be a brain-friendly sugar alternative to the conventional household sugar, which you can definitely indulge in small amounts without harming your health!



  1. Roy, S., Chikkerur, J., Roy, S. C., Dhali, A., Kolte, A. P., Sridhar, M., & Samanta, A. K. (2018). Tagatose as a Potential Nutraceutical: Production, Properties, Biological Roles, and Applications. Journal of Food Science, 83(11), 2699-2709.
  2. Guerrero-Wyss, M., Durán Agüero, S., & Angarita Dávila, L. (2018). D-Tagatose Is a Promising Sweetener to Control Glycaemia: A New Functional Food. BioMed Research International, 2018, 8718053. https://doi.org/10.1155/2018/8718053
  3. W. Donner, J. F. Wilber, and D. Ostrowski, “D-tagatose, a novel hexose: Acute effects on carbohydrate tolerance in subjects with and without type 2 diabetes,” Diabetes, Obesity and Metabolism, vol. 1, no. 5, pp. 285-291, 1999. https://doi.org/10.1046/j.1463-1326.1999.00039.x
  4. Ensor, J. Williams, R. Smith, A. Banfield, and R. A. Lodder, “Effects of three low-doses of D-tagatose on glycemic control over six months,”Journal of Endocrinology, Diabetes & Obesity, vol. 2, article 1057, no. 4, 2014. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4820068/
  5. Ensor, M., Banfield, A. B., Smith, R. R., Williams, J., & Lodder, R. A. (2015). Safety and Efficacy of D-Tagatose in Glycemic Control in Subjects with Type 2 Diabetes. Journal of endocrinology, diabetes & obesity, 3(1), 1065. https://pubmed.ncbi.nlm.nih.gov/27054147/
  6. Venema, K., Vermunt, S. H. F., & Brink, E. J. (2005). D-tagatose increases butyrate production by the colonic microbiota in healthy men and women. Microbial Ecology in Health and Disease, 17(1), 47-57. https://doi.org/10.1080/08910600510035093
  7. Mirzaei, R., Bouzari, B., Hosseini-Fard, S. R., Mazaheri, M., Ahmadyousefi, Y., Abdi, M., Jalalifar, S., Karimitabar, Z., Teimoori, A., Keyvani, H., Zamani, F., Yousefimashouf, R., & Karampoor, S. (2021). Role of microbiota-derived short-chain fatty acids in nervous system disorders. Biomedicine & Pharmacotherapy, 139, 111661.https://doi.org/10.1016/j.biopha.2021.111661

Figure 1: https://de.wikipedia.org/wiki/Tagatose#/media/Datei:DL-Tagatose.svg