title: Possible effects of dietary polyphenols on sugar absorption and digestion.
abstract: Excessive post-prandial glucose excursions are a risk factor for developing diabetes, associated with impaired glucose tolerance. One way to limit the excursion is to inhibit the activity of digestive enzymes for glucose production and of the transporters responsible for glucose absorption. Flavonols, theaflavins, gallate esters, 5-caffeoylqunic acid and proanthocyanidins inhibit α-amylase activity. Anthocyanidins and catechin oxidation products, such as theaflavins and theasinsensins, inhibit maltase; sucrase is less strongly inhibited but anthocyanidins seem somewhat effective. Lactase is inhibited by green tea catechins. Once produced in the gut by digestion, glucose is absorbed by SGLT1 and GLUT2 transporters, inhibited by flavonols and flavonol glycosides, phlorizin and green tea catechins. These in vitro data are supported by oral glucose tolerance tests on animals, and by a limited number of human intervention studies on polyphenol-rich foods. Acarbose is a drug whose mechanism of action is only through inhibition of α-amylases and α-glucosidases, and in intervention studies gives a 6% reduction in diabetes risk over 3 years. A lifetime intake of dietary polyphenols, assuming the same mechanism, has therefore a comparable potential to reduce diabetes risk, but more in vivo studies are required to fully test the effect of modulating post-prandial blood glucose in humans.
authors.affiliation: School of Food Science and Nutrition, University of Leeds, Leeds LS2 9JT, UK. g.williamson@leeds.ac.uk
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
mesh_terms: D000042:Absorption; D020909:Acarbose / Q000494:pharmacology; D000818:Animals; D000872:Anthocyanins / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D044946:Biflavonoids / Q000494:pharmacology; D050260:Carbohydrate Metabolism / Q000187:drug effects*; D002392:Catechin / Q000494:pharmacology; D003920:Diabetes Mellitus / Q000517:prevention & control; D004032:Diet; D004063:Digestion / Q000187:drug effects; D004186:Disaccharidases / Q000378:metabolism; D044948:Flavonols / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D051273:Glucose Transporter Type 2 / Q000235:genetics / Q000378:metabolism; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D043322:Lactase / Q000037:antagonists & inhibitors / Q000378:metabolism; D023421:Models, Animal; D009005:Monosaccharides / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology; D059808:Polyphenols / Q000494:pharmacology*; D019518:Postprandial Period / Q000187:drug effects; D012307:Risk Factors; D051269:Sodium-Glucose Transporter 1 / Q000235:genetics / Q000378:metabolism; D013393:Sucrase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013662:Tea / Q000737:chemistry; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D000872:Anthocyanins; D000975:Antioxidants; D044946:Biflavonoids; D044948:Flavonols; D051273:Glucose Transporter Type 2; D065089:Glycoside Hydrolase Inhibitors; D009005:Monosaccharides; D010936:Plant Extracts; D059808:Polyphenols; C495680:SLC2A2 protein, human; C495674:SLC5A1 protein, human; D051269:Sodium-Glucose Transporter 1; D013662:Tea; C056068:theaflavin; D002392:Catechin; D004186:Disaccharidases; D000516:alpha-Amylases; D043322:Lactase; D000520:alpha-Glucosidases; D013393:Sucrase; D005947:Glucose; D020909:Acarbose