Skip to main content
. 2020 Jul 6;7:75. doi: 10.3389/fnut.2020.00075

Table 2.

Chemical and physiological characteristics of sugars and other glycemic carbohydrates.

CHO Type Digestive enzyme In gut lumen Enterocyte uptake In blood Possible metabolic fate options GI
Glucose Monosaccharide - Glucose - Glucose Used as fuel, stored as glycogen and/or converted to other metabolites 100
Fructose Monosaccharide - Fructose - Lactate, glucose, fructose Partially converted to lactic acid and glucose, used as fuel or stored as glycogen, and fatty acids used as fuel or triacylglycerol stored as lipid 19
Sucrose Disaccharide: glucose -fructose, α1-2 bond Sucrase Glucose, fructose Glucose, fructose glucose, lactate, fructose see glucose and fructose above 65
Isomaltulose Disaccharide: glucose -fructose, α1-6 bond Isomaltase Glucose, fructose Glucose, fructose See fate of glucose and fructose above 32
Galactose Monosaccharide - Galactose - Galactose Liver conversion to glucose, see fate of glucose above 25
Lactose Disaccharide: glucose -galactose, α1-4 bond Lactase Glucose, galactose Glucose, galactose Glucose, galactose See fate of glucose and galactose above 45
Honey Glucose 30.3%, fructose 38.4%, sucrose 1.3% Sucrase Glucose, fructose Glucose, fructose Glucose, lactate, fructose See glucose and fructose above 50
Maple syrup Sucrose 98%, glucose 1%, fructose 1% Sucrase Glucose, fructose Glucose, fructose Glucose, lactate, fructose See glucose and fructose above 54
HFCS 55 Fructose 55%, glucose, 43% gluco-oligo saccharides 3% α-Dextrinase Glucose, fructose Glucose, fructose Glucose, lactate, fructose See glucose and fructose above 58
Starch Glucose polymers: amylopectin α1-4 and α1-6 bonds. Amylose α1-4 bonds Amylase from saliva, pancreas Maltose, glucose Maltose, glucose Glucose See fate of glucose above 40–110*
Maltodextrins Glucose polymer, α1-4 glycosidic bonds α -Dextrinase Glucose, maltose Maltose, glucose Glucose See glucose above 110
Maltose Disaccharide: glucose-glucose, α1-4 glycosidic bond Maltase Glucose Glucose Glucose See glucose above 105
Trehalose Disaccharide: glucose-glucose, α1-1 glycosidic bond Trehalase Glucose Glucose Glucose See glucose above 70
Sorbitol* Sugar alcohol - Sorbitol - Sorbitol Liver conversion to fructose and glucose, see above 4

For a review of fructose, see Tappy and Lê (12). For a review of lactose and galactose, see University of Waterloo (13). One example of a low-caloric/low-glycemic sugar replacer is given. In the gut, sorbitol, a sugar-alcohol, is slowly absorbed (25–80% of the consumed dose) by facilitated diffusion. Absorbed sorbitol passes the liver, where it is converted to fructose and glucose (14). The unabsorbed fraction is transported to the large bowel, where it is fermented. When sorbitol is consumed in high doses, potential side effects can occur as a result of osmotic water shifts from blood into the gut, resulting in rumbling, loose stools, or diarrhea (extensive details about polyols can be found in Livesey (14), Ghosh and Sudha (15), Rice et al. (16). For a review of low- and non-caloric/non-glycemic sweeteners compared with caloric sweeteners, see Rogers et al. (17). *The glycemic index of starchy foods varies according to the molecular content of amylose, amylopectin, fiber, presence of protein, and characteristics of the food matrix, resulting in a range of reported values. For extensive glycemic index data [see (18)], International Tables of Glycemic Index and Glycemic Load Values, the online University of Sydney searchable data GI; http://www.glycemicindex.com/foodSearch.php. For further extensive details, see Queen Mary University London (19), Nomenclature of Carbohydrates (Available online at: https://www.qmul.ac.uk/sbcs/iupac/2carb/00n01.html#0121) and nomenclature of sugar alcohols (20).