Effect of green tea supplementation on insulin sensitivity in Sprague-Dawley rats.
Epidemiological observations and laboratory studies have shown that green tea has a variety of health effects, including antitumor, antioxidative, and hypolipidemic activities. The aim of this study was to examine whether it had an effect on glucose tolerance and insulin sensitivity in Sprague-Dawley rats. In experiment 1 (in vivo study), rats were divided into two groups: a control group fed standard chow and deionized distilled water and a "green tea" group fed the same chow diet but with green tea instead of water (0.5 g of lyophilized green tea powder dissolved in 100 mL of deionized distilled water). After 12 weeks of green tea supplementation, the green tea group had lower fasting plasma levels of glucose, insulin, triglyceride, and free fatty acid than the control rats. Insulin-stimulated glucose uptake of, and insulin binding to, adipocytes were significantly increased in the green tea group. In experiment 2 (in vitro study), a tea polyphenol extract was used to determine its effect on insulin activity in vitro. Green tea polyphenols (0.075%) significantly increased basal and insulin-stimulated glucose uptake of adipocytes. Results demonstrated that green tea increases insulin sensitivity in Sprague-Dawley rats and that green tea polyphenol is one of the active components.
Wu
Liang-Yi
LY
Graduate Institute of Food Science and Technology, National Taiwan University, Taipei, Taiwan.
Juan
Chi-Chang
CC
Ho
Low-Tone
LT
Hsu
Yung-Pei
YP
Hwang
Lucy Sun
LS
D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D005419:Flavonoids / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism; D005951:Glucose Tolerance Test; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007333:Insulin Resistance; D008297:Male; D010636:Phenols / Q000494:pharmacology; D059808:Polyphenols; D051381:Rats; D017207:Rats, Sprague-Dawley; D013662:Tea / Q000737:chemistry
D005419:Flavonoids; D007328:Insulin; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D005947:Glucose