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ARS Home » Northeast Area » Beltsville, Maryland (BHNRC) » Beltsville Human Nutrition Research Center » Diet, Genomics and Immunology Laboratory » Research » Publications at this Location » Publication #208910
Title: Green tea extract decreases oxidative stress and improves insulin sensitivity in an animal model of insulin resistance, the fructose- fed rat

Author
item HININGER-FAVIER, ISABELLE - Joseph Fourier University
item BENARABA, RACHIDA - J. FOURIER U, GRENOBLE,FR
item COVES, SARA - UNILEVER FR,F92842 RUEIL
item Anderson, Richard
item ROUSSEL, ANNE - Joseph Fourier University

Submitted to: Journal of American College of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2007
Publication Date: 8/20/2009
Citation: Hininger-Favier, I., Benaraba, R., Coves, S., Anderson, R.A., Roussel, A.M. 2009. Green tea extract decreases oxidative stress and improves insulin sensitivity in an animal model of insulin resistance, the fructose-fed rat. Journal of the American College of Nutrition. 28:355-361.

Interpretive Summary: Metabolic syndrome is characterized by insulin resistance, dyslipidemia, and increased oxidative stress. Tea polyphenols, as both insulin potentiating factors and antioxidants, might act in preventing the metabolic syndrome. Early signs of the metabolic syndrome are obesity and insulin resistance, and later consequences include diabetes and cardiovascular diseases. Tea is known to be a potent antioxidant, and we have shown previously that tea also improves insulin function. The objective of this study was to determine the effects of green tea extract on oxidative stress and insulin sensitivity, using fructose-fed diet rats as an animal model of the metabolic syndrome. Rats receiving added tea solids exhibited a decrease of glycemia, insulinemia, and triglyceridemia; and oxidative stress markers in the blood were improved. In conclusion, addition of green tea extracts to animals with the metabolic syndrome led to beneficial effects on oxidative stress markers and on insulin/glucose regulation. This work should be of interest, not only to the scientific community, but also to the estimated one-third of the adult population who have the metabolic syndrome.

Technical Abstract: Metabolic syndrome is characterized by insulin resistance, dyslipidemia, and increased oxidative stress. Tea polyphenols, as both insulin potentiating factors and antioxidants, might act in preventing the metabolic syndrome. We aimed to determine the effects of green tea extract consumption on oxidative stress and insulin sensitivity, using fructose-fed diet rats as an animal model of the metabolic syndrome. Wistar rats, 10 per group, received a high fructose diet (FD) for six weeks, or FD plus either 1 or 2 g of green tea solids/kg diet. Signs of the metabolic syndrome (hyperglycemia, hypertriglyceridemia, and hyperinsulinemia) were developed in rats receiving the FD diet compared with those of the control group. Rats receiving added tea solids exhibited an important decrease of glycemia, insulinemia, and triglyceridemia, indicating an insulin potentiating effect of tea. In parallel, oxidative stress was decreased. Significantly lowered plasma lipid peroxidation, sulfhydryl (SH) group oxidation, and DNA oxidative damage were also present. In conclusion, addition of green tea extracts to animals with the metabolic syndrome led to beneficial effects of green tea, both on oxidative stress markers, and on insulin/glucose regulation, indicating that tea may be of benefit to people at risk of the metabolic syndrome and diabetes.