Impact of Dietary Polyphenols on Carbohydrate Metabolism

Abstract

Polyphenols, including flavonoids, phenolic acids, proanthocyanidins and resveratrol, are a large and heterogeneous group of phytochemicals in plant-based foods, such as tea, coffee, wine, cocoa, cereal grains, soy, fruits and berries. Growing evidence indicates that various dietary polyphenols may influence carbohydrate metabolism at many levels. In animal models and a limited number of human studies carried out so far, polyphenols and foods or beverages rich in polyphenols have attenuated postprandial glycemic responses and fasting hyperglycemia, and improved acute insulin secretion and insulin sensitivity. The possible mechanisms include inhibition of carbohydrate digestion and glucose absorption in the intestine, stimulation of insulin secretion from the pancreatic β–cells, modulation of glucose release from the liver, activation of insulin receptors and glucose uptake in the insulin-sensitive tissues, and modulation of intracellular signalling pathways and gene expression. The positive effects of polyphenols on glucose homeostasis observed in a large number of in vitro and animal models are supported by epidemiological evidence on polyphenol-rich diets. To confirm the implications of polyphenol consumption for prevention of insulin resistance, metabolic syndrome and eventually type 2 diabetes, human trials with well-defined diets, controlled study designs and clinically relevant end-points together with holistic approaches e.g., systems biology profiling technologies are needed.

Different postprandial acute response in healthy subjects to three strawberry jams varying in carbohydrate and antioxidant content: a randomized, crossover trial

“…Moreover, products with low amounts of simple sugars, low glycemic index or rich in fiber can be of interest in the management of blood glucose alterations [22][23][24]. In that context, fruits and fruit-derived products have shown some healthy benefits, improving carbohydrate, lipid profile and, oxidative status [25,26]. However, to date little is known about the effect of the addition of natural antioxidants to fruit-derived products, such as jams.…”

Propolis residue inclusion in the diet affects digestive enzyme activity in broiler chickens

“…This result was comparable to the inclusion of crude propolis , which showed that pancreatic amylase activity decreased with dietary inclusion of crude propolis, possibly related to the inhibitory effect of propolis polyphenols on amylase and maltase activity (MATSUI et al, 2004;ZHANG et al, 2015), despite the low concentration of these compounds in the residue. Many authors have shown that amylase and maltase activity may be decreased by anthocyanins, phenolic acids, and flavonoids (FORESTER et al, 2012;HANHINEVA et al, 2010;MCDOUGALL et al, 2005). This is due to either non-competitive inhibition associated with the number of hydroxyl groups on the B-ring of the flavonoid skeleton, and consequent formation of hydrogen bonds between the hydroxyl groups of the polyphenol ligands and catalytic site of the enzyme (LO PIPARO et al, 2008), or the antioxidant properties of the polyphenols, which may also inhibit amylase activity (HASHIM et al, 2013).…”

Cocoa Flavanol Intake and Biomarkers for Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

“…Flavanols have been shown to inhibit glucosidase and glucose absorption from the intestine, protect pancreatic b cells, increase insulin secretion, activate insulin receptors and glucose uptake in insulin-sensitive tissues, and modulate intracellular signaling pathways and genes involved in gluconeogenesis and glycogenesis (15,52). Flavanols may also improve insulin sensitivity by increasing NO bioavailability and inhibiting production of reactive oxygen species and nitrogen species (5, 6).…”