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Green tea, black tea, and epigallocatechin modify body composition, improve glucose tolerance, and differentially alter metabolic gene expression in rats fed a high-fat diet

Chen, Nora and Bezzina, Rebbeca and Hinch, Eddie and Lewandowski, Paul and Cameron-Smith, David and Mathai, Michael L and Jois, Mark and Weisinger, Richard (2009) Green tea, black tea, and epigallocatechin modify body composition, improve glucose tolerance, and differentially alter metabolic gene expression in rats fed a high-fat diet. Nutrition Research, 29 (1). pp. 784-793. ISSN 0271-5317

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Abstract

The mechanisms of how tea and epigallocatechin-3-gallate (EGCG) lower body fat are not completely understood. This study investigated long-term administration of green tea (GT), black tea (BT), or isolated EGCG (1 mg/kg per day) on body composition, glucose tolerance, and gene expression related to energy metabolism and lipid homeostasis; it was hypothesized that all treatments would improve the indicators of metabolic syndrome. Rats were fed a 15% fat diet for 6 months from 4 weeks of age and were supplied GT, BT, EGCG, or water. GT and BT reduced body fat, whereas GT and EGCG increased lean mass. At 16 weeks GT, BT, and EGCG improved glucose tolerance. In the liver, GT and BT increased the expression of genes involved in fatty acid synthesis (SREBP-1c, FAS, MCD, ACC) and oxidation (PPAR-α, CPT-1, ACO); however, EGCG had no effect. In perirenal fat, genes that mediate adipocyte differentiation were suppressed by GT (Pref-1, C/EBP-β, and PPAR-γ) and BT (C/EBP-β), while decreasing LPL, HSL, and UCP-2 expression; EGCG increased expression of UCP-2 and PPAR-γ genes. Liver triacylglycerol content was unchanged. The results suggest that GT and BT suppressed adipocyte differentiation and fatty acid uptake into adipose tissue, while increasing fat synthesis and oxidation by the liver, without inducing hepatic fat accumulation. In contrast, EGCG increased markers of thermogenesis and differentiation in adipose tissue, while having no effect on liver or muscle tissues at this dose. These results show novel and separate mechanisms by which tea and EGCG may improve glucose tolerance and support a role for these compounds in obesity prevention.

Item Type: Article
Additional Information:

Online ISSN: 1879-0739

Uncontrolled Keywords: ResPubID17995. Green tea, black tea, epigallocatechin, laboratory rats, adipose tissue, gene expression, glucose tolerance tests, body fat, energy metabolism, lipid homeostasis
Subjects: Faculty/School/Research Centre/Department > School of Biomedical and Health Sciences
FOR Classification > 0606 Physiology
FOR Classification > 1111 Nutrition and Dietetics
SEO Classification > 970111 Expanding Knowledge in the Medical and Health Sciences
Depositing User: VUIR
Date Deposited: 12 Oct 2011 04:14
Last Modified: 12 Oct 2011 04:14
URI: http://vuir.vu.edu.au/id/eprint/4222
DOI: 10.1016/j.nutres.2009.10.003
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Citations in Scopus: 47 - View on Scopus

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