Effect of Decaffeinated Green and Black Tea Extracts on Energy Metabolism in Mice Fed a High Fat/High Sucrose/Western Diet

Abstract

Although green tea (GT) and black tea (BT) are chemically very different, both reduce body weight and fat depots in male C57BL/6J mice fed a high‐fat/high‐sucrose (HF/HS) diet. A portion of GT polyphenols is absorbed in the small intestine while the majority of high molecular weight polyphenols from BT reach the large intestine. In the colon all tea polyphenols are converted to smaller phenolic compounds by the microflora. We have demonstrated that GT and BT dramatically change the composition of the intestinal microflora. It is the objective of the present study to determine intestinal and hepatic targets of tea polyphenols contributing to the anti‐obesogenic activity of GT and BT.48 C57BL/6 male mice were randomly assigned to one of four treatment groups: control HF/HS (Western) diet (32% kcal from butter fat and corn oil, 25% kcal from sucrose), or a HF/HS‐diet supplemented with either GT or BT extract providing 0.25% polyphenols, or a low fat diet (10.6% kcal from fat) for 4 weeks. All observations are in comparison to the HF/HS‐diet fed control mice. GT and BT administration decreased body weight, epidydimal, mesenteric and subcutaneous fat as determined by weight. Only BT significantly increased propionic acid and i‐butyric acid in the cecum as determined by gas chromatography. Real‐time quantitative PCR demonstrated that GT and BT decreased gene expression of fatty acid transporters in ileum tissue of fatty acid binding protein 2 (Fabp2) significantly and BT induced a trend to decrease gene expression of fatty acid binding protein 4 (Fatp4) and cluster of differentiation/fatty acid translocase (Cd36/Fat). Gene expression of the following hepatic key regulatory enzymes of fatty acid β‐oxidation was increased significantly by GT: 1) Carnitine palmitoyl transferase 1 and 2 (Cpt1a, Cpt1b, Cpt2), that regulate transport of cytosolic fatty acids to mitochondria and 2) long chain and very long chain acetyl CoA dehydrogenase (Lcad, VLcad), that catalyze the first step in FA β‐oxidation in the mitochondria. In the liver of mice consuming the HF/HS‐BT diet AMPK protein phosphorylation was increased significantly as determined by Western blot.In summary, the anti‐obesity effects of GT and BT were induced through different mechanisms. Only GT stimulated liver energy expenditure directly, while BT increased SCFA formation significantly leading to stimulation of AMPK phosphorylation and both teas reduced intestinal fatty acid transport.Support or Funding InformationSupported by NIH RO3CA171583 and departmental funds of the Center for Human Nutrition Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles