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Br J Nutr. 2017 Feb;117(4):519-531. doi: 10.1017/S0007114517000393. Epub 2017 Mar 14.

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

Author information

1
1Institute of Nutrition and Functional Foods,Laval University,Quebec,Canada, G1V 0A6.
2
2School of Nutrition,Laval University,Quebec,Canada, G1V 0A6.

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.

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

PMID:
28290272
PMCID:
PMC5426341
DOI:
10.1017/S0007114517000393
[Indexed for MEDLINE]
Free PMC Article

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