title: Strawberry and cranberry polyphenols improve insulin sensitivity in insulin-resistant, non-diabetic adults: a parallel, double-blind, controlled and randomised clinical trial.
abstract: Plant-derived foods rich in polyphenols are associated with several cardiometabolic health benefits, such as reduced postprandial hyperglycaemia. However, their impact on whole-body insulin sensitivity using the hyperinsulinaemic-euglycaemic clamp technique remains under-studied. We aimed to determine the effects of strawberry and cranberry polyphenols (SCP) on insulin sensitivity, glucose tolerance, insulin secretion, lipid profile, inflammation and oxidative stress markers in free-living insulin-resistant overweight or obese human subjects (n 41) in a parallel, double-blind, controlled and randomised clinical trial. The experimental group consumed an SCP beverage (333 mg SCP) daily for 6 weeks, whereas the Control group received a flavour-matched Control beverage that contained 0 mg SCP. At the beginning and at the end of the experimental period, insulin sensitivity was assessed by a hyperinsulinaemic-euglycaemic clamp, and glucose tolerance and insulin secretion by a 2-h oral glucose tolerance test (OGTT). Insulin sensitivity increased in the SCP group as compared with the Control group (+0·9 (sem 0·5)×10-3 v. -0·5 (sem 0·5)×10-3 mg/kg per min per pmol, respectively, P=0·03). Compared with the Control group, the SCP group had a lower first-phase insulin secretion response as measured by C-peptide levels during the first 30 min of the OGTT (P=0·002). No differences were detected between the two groups for lipids and markers of inflammation and oxidative stress. A 6-week dietary intervention with 333 mg of polyphenols from strawberries and cranberries improved insulin sensitivity in overweight and obese non-diabetic, insulin-resistant human subjects but was not effective in improving other cardiometabolic risk factors.
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Martine
authors.initials: M
authors.lastname: Paquette
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Ana S
authors.initials: AS
authors.lastname: Medina Larqué
authors.affiliation: 2School of Nutrition,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: S J
authors.initials: SJ
authors.lastname: Weisnagel
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Yves
authors.initials: Y
authors.lastname: Desjardins
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Julie
authors.initials: J
authors.lastname: Marois
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Pilon
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Dudonné
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: André
authors.initials: A
authors.lastname: Marette
authors.affiliation: 1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
authors.forename: Hélène
authors.initials: H
authors.lastname: Jacques
mesh_terms: D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D003920:Diabetes Mellitus; D004311:Double-Blind Method; D005260:Female; D031985:Fragaria / Q000737:chemistry*; D005638:Fruit / Q000737:chemistry; D005951:Glucose Tolerance Test; D006801:Humans; D007249:Inflammation / Q000097:blood; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000178:diet therapy; D018384:Oxidative Stress / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology*; D029799:Vaccinium macrocarpon / Q000737:chemistry*
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D008055:Lipids; D010936:Plant Extracts; D059808:Polyphenols
keywords:  IAUC incremental AUC;  IGT impaired glucose tolerance;  M/I insulin sensitivity index;  OGTT oral glucose tolerance test;  SCP strawberry and cranberry polyphenols;  UHPLC ultra-high performance liquid chromatography (UHPLC); Cranberries; Glucose metabolism; Insulin secretion; Insulin sensitivity; Insulin-resistant subjects; Polyphenols; Strawberries