Rare sugars: metabolic impacts and mechanisms of action: a scoping review

Abstract

Food manufacturers are under increasing pressure to limit the amount of free sugars in their products. Many have reformulated products to replace sucrose, glucose and fructose with alternative sweeteners, but some of these have been associated with additional health concerns. Rare sugars are “monosaccharides and their derivatives that hardly exist in nature”, and there is increasing evidence that they could have health benefits. This review aimed to scope the existing literature in order to identify the most commonly researched rare sugars, to ascertain their proposed health benefits, mechanisms of action and potential uses, and to highlight knowledge gaps. A process of iterative database searching identified 55 relevant articles. The reported effects of rare sugars were noted, along with details of the research methodologies conducted. Our results indicated that the most common rare sugars investigated are D-psicose and D-tagatose, with the potential health benefits divided into three topics: glycaemic control, body composition and cardiovascular disease. All the rare sugars investigated have the potential to suppress postprandial elevation of blood glucose and improve glycaemic control in both human and animal models. Some animal studies have suggested that certain rare sugars may also improve lipid profiles, alter the gut microbiome and reduce pro-inflammatory cytokine expression. The present review demonstrates that rare sugars could play a role in reducing the development of obesity, type 2 diabetes, and/or cardiovascular disease. However, understanding of the mechanisms by which rare sugars may exert their effects is limited, and their effectiveness when used in reformulated products is unknown.

Rare Sugar Metabolism and Impact on Insulin Sensitivity along the Gut–Liver–Muscle Axis In Vitro

“…Hereby, the research builds further upon the current knowledge on rare sugars and the existing in vitro models for testing cellular impact of nutrients. Currently, there is only a small number of rare sugars for which the metabolic health impact is known, as mentioned in recent reviews [ 35 , 36 ], and this is the first study to investigate metabolic health effects of the rare sugars D-Glc-α1,2-D-Gal, D-Glc-α1,2-D-Rib and D-Glc-α1,3-L-Ara. In addition, this study has used cellular energetics to obtain knowledge on cellular effects of disaccharides, whereas previous research has mainly focused on conventional monosaccharides [ 25 , 37 ].…”

D-Allulose Reduces Hypertrophy and Endoplasmic Reticulum Stress Induced by Palmitic Acid in Murine 3T3-L1 Adipocytes

“…Recently, major concerns have been expressed regarding the intake of metabolizable free sugars, which are usually replaced by artificial high-intensity sweeteners, such as aspartame, acesulfame potassium, saccharin, sucralose, and others, approved as food additives by the European Food Safety Authority (EFSA) and U.S. Food and Drug Administration (FDA) [8,9]. However, these alternative sweeteners are associated with unfavorable effects on health, such as glucose intolerance and failure to cause weight reduction [10]. Interestingly, naturally occurring rare sugars have recently appeared as a valuable alternative category of sweeteners.…”

Importance of Carbohydrate Quality: What Does It Mean and How to Measure It?

“…Isomaltulose, an isomer of sucrose with glucose and fructose linked through an α-1,6 linkage instead of an α-1,2 linkage in sucrose, is digested at a slower rate than sucrose due to lower intestinal enzyme affinity, thus lowering postprandial glucose response and related inflammatory markers in patients with type 2 diabetes ( 21 ). Among other rare sugars, allulose is a C3 epimer of D-fructose and tagatose a stereoisomer of D-fructose ( 22 ). Due to their different conformations, they are either not metabolized (in the case of allulose) or not absorbed (in the case of tagatose), which results in a lower caloric content for both rare sugars.…”

“…Beyond their lower caloric content, some studies have suggested they may have additional benefits by decreasing glucose-induced postprandial glycemia. The postulated mechanism may involve inhibition of α-glucosidase ( 22 ). The associations between total dietary carbohydrate intake and health-related outcomes have been intensively studied but remain debated.…”