Strawberry and cranberry polyphenols improve insulin sensitivity in insulin-resistant, non-diabetic adults: a parallel, double-blind, controlled and randomised clinical trial

• Published in: British journal of nutrition Vol. 117; no. 4; pp. 519 - 531
• Main Authors: Paquette, Martine, Medina Larqué, Ana S., Weisnagel, S. J., Desjardins, Yves, Marois, Julie, Pilon, Geneviève, Dudonné, Stéphanie, Marette, André, Jacques, Hélène
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 28.02.2017
• Subjects: adults; beverages; Blood Glucose - metabolism; c-peptide; C-Peptide - blood; Clinical trials; cranberries; Diabetes Mellitus; Diet; Double-Blind Method; Female; Fragaria; Fragaria - chemistry; Fruit - chemistry; Glucose; glucose tolerance; Glucose Tolerance Test; glucose tolerance tests; Health risks; Human and Clinical Nutrition; Humans; hyperglycemia; Inflammation; Inflammation - blood; Insulin - blood; Insulin Resistance; insulin secretion; Intervention; lipid composition; Lipids; Lipids - blood; Male; Middle Aged; nutritional intervention; Obesity; Obesity - blood; Obesity - diet therapy; overweight; Oxidative stress; Oxidative Stress - drug effects; Plant Extracts - pharmacology; plant-based foods; Polyphenols; Polyphenols - pharmacology; randomized clinical trials; Risk factors; strawberries; Vaccinium macrocarpon - chemistry; Glucose metabolism; Strawberries; Insulin sensitivity; Polyphenols; Insulin-resistant subjects; Cranberries; Insulin secretion; SCP strawberry and cranberry polyphenols; IGT impaired glucose tolerance; UHPLC ultra-high performance liquid chromatography (UHPLC); M/I insulin sensitivity index; IAUC incremental AUC; OGTT oral glucose tolerance test
• ISSN: 0007-1145; 1475-2662; 1475-2662
• DOI: 10.1017/S0007114517000393

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.