Allulose in human diet: the knowns and the unknowns

Abstract

D-Allulose, also referred to as psicose, is a C3-epimer of D-fructose used as a sugar substitute in low calorie products. It can be formed naturally during processing of food and drinks containing sucrose and fructose or is prepared by chemical synthesis or via enzymatic treatment with epimerases from fructose. Estimated intakes via western style diets including sweetened beverages are below 500 mg per day but, when used as a sugar replacement, intake may reach 10 to 30g per day depending on the food consumed. Due to its structural similarity with fructose, allulose uses the same transport and distribution pathways. But in contrast to fructose, the human genome does not encode for enzymes that are able to metabolize allulose leading to an almost complete renal excretion of the absorbed dose and near-to-zero caloric yield. However, in vitro studies have shown that certain bacteria such as Klebsiella pneumonia are able to utilize allulose as a substrate. This finding has been a subject of concern, since Klebsiella pneumoniae represents an opportunistic human pathogen. It therefore raised the question of whether a high dietary intake of allulose may cause an undesirable growth advantage for potentially harmful bacteria at mucosal sites such as the intestine or at systemic sites following invasive infection. In this brief review, we discuss the current state of science on these issues and define the research needs to better understand the fate of allulose and its metabolic and microbiological effects when ingested as a sugar substitute.

Application of Emerging Techniques in Reduction of the Sugar Content of Fruit Juice: Current Challenges and Future Perspectives

“…However, despite the existence of beneficial aspects of the use of allulose, in vitro studies have shown that bacteria such as Klebsiella pneumonia (an opportunistic human pathogen) can utilize allulose as a substrate. This raises the question of whether a high dietary intake of D-psicose may contribute to the growth of potentially harmful bacteria at mucosal sites such as the intestine [ 113 ].…”

The Potential Effect of Honey-derived D-Allulose in Counteracting Hyperglycemia by Time and Dose Dependent Manner in Diabetes Mellitus

“…8 Additionally, D-allulose is not involved in glucose metabolism, is not metabolized in hepar, does not alter pancreatic and insulin function, and does not influence post-prandial blood glucose levels. 7,11,13,14 Most of the D-allulose was excreted in the form of urine. Only a small part of D-allulose is excreted in faecal form.…”

“…Furthermore, it is not influencing pancreatic function nor altering the blood glucose level. 7,11,13,14 Recently, despite its role as a safe sweetener, evidence has elucidated potential medicinal role of D-allulose as an anti-diabetic through its role as an insulin mimetic and modulator of some insulin-responsive genes. 11 Our result confirmed previous findings that once daily treatment of 0.1 g/kg BW D-allulose significantly reduces post-prandial blood glucose levels in the diabetic rats on days 56 and 84 compared to their diabetic counterparts without treatment, though the blood glucose level reduction did not reach normal levels (Table 1).…”

“…12 Thus, Dallulose is an ideal choice of natural, safe sweetener and has recently been used worldwide as an artificial sweetener since it is not only low in calories but also metabolized to a lesser extent than other normal sugars. 7,13,14 Despite its role as a sweetener, D-allulose was also found to have a direct anti-diabetic property. Matsuo T et al, 2006 found that Dallulose resembles an alpha-glucosidase inhibitor by inhibiting the intestinal alpha-glucosidase enzyme, which further suppressed the postprandial glycemic response in the rat.…”

Intestinal absorption of D-fructose isomers, D-allulose, D-sorbose and D-tagatose, via glucose transporter type 5 (GLUT5) but not sodium-dependent glucose cotransporter 1 (SGLT1) in rats

“…The EU introduced D-tagatose as a new food ingredient (18) . Many kinds of rare sugar containing foods have already been marketed in several countries, including the USA, EU and Japan (19–21) .…”