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Open Access Research

Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice

Henrik Ortsäter1, Nina Grankvist1, Swen Wolfram2, Nicolas Kuehn3 and Åke Sjöholm1*

Author Affiliations

1 Karolinska Institutet, Department of Clinical Science and Education, Södersjukhuset, SE-118 83 Stockholm, Sweden

2 DSM Nutritional Products Ltd, Department of Human Nutrition and Health, P.O. Box 2676, Bldg.241/958, CH-4002 Basel, Switzerland

3 Diavet Labor, Schlyffistrasse 10, CH-8806, Bäch/SZ Zurich, Switzerland

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Nutrition & Metabolism 2012, 9:11  doi:10.1186/1743-7075-9-11

Published: 14 February 2012

Abstract

Background

Green tea was suggested as a therapeutic agent for the treatment of diabetes more than 70 years ago, but the mechanisms behind its antidiabetic effect remains elusive. In this work, we address this issue by feeding a green tea extract (TEAVIGO™) with a high content of epigallocatechin gallate (EGCG) or the thiazolidinedione PPAR-γ agonist rosiglitazone, as positive control, to db/db mice, an animal model for diabetes.

Methods

Young (7 week-old) db/db mice were randomized and assigned to receive diets supplemented with or without EGCG or rosiglitazone for 10 weeks. Fasting blood glucose, body weight and food intake was measured along the treatment. Glucose and insulin levels were determined during an oral glucose tolerance test after 10 weeks of treatment. Pancreata were sampled at the end of the study for blinded histomorphometric analysis. Islets were isolated and their mRNA expression analyzed by quantitative RT-PCR.

Results

The results show that, in db/db mice, EGCG improves glucose tolerance and increases glucose-stimulated insulin secretion. EGCG supplementation reduces the number of pathologically changed islets of Langerhans, increases the number and the size of islets, and heightens pancreatic endocrine area. These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers, possibly linked to the antioxidative capacity of EGCG.

Conclusions

This study shows that the green tea extract EGCG markedly preserves islet structure and enhances glucose tolerance in genetically diabetic mice. Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes.

Keywords:
Green tea; Epigallocatechin gallate; Diabetes islet; Beta cell; Insulin secretion