J Korean Diabetes Assoc.  2006 May;30(3):217-225. 10.4093/jkda.2006.30.3.217.

The Effect of Green Tea Polyphenol on Plasma Glucose, Lipid Levels and Antioxidant Systems in Type 2 Diabetic Patients

• Suk JH
• Kim MK
• Ju JW
• Han JS
• Park JH

• KMID: 2177616
• DOI: http://doi.org/10.4093/jkda.2006.30.3.217

Abstract

BACKGROUND: Green-tea polyphenol (GTP) is a well known antioxidant with favorable effect on blood glucose and lipid level in animal models. We were to investigate the effects of GTP on plasma glucose, lipid and antioxidant systems in patients with type 2 diabetes.
METHODS
We recruited non-complicated type 2 diabetic patients with stable glycemic control by oral hypoglycemic agents. Subjects were randomly assigned to GTP group or placebo group for 12 weeks. Fasting plasma glucose (FPG), HbA1c, C-peptide, lipid levels, liver function test, renal function test, urine microalbumin, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSHPx) activities were measured at baseline and after 12 weeks of treatment.
RESULTS
At baseline, there were no significant differences in age, body mass index, duration of diabetes, dietary status, HbA1c, total cholesterol, LDL cholesterol, and HDL cholesterol levels between GTP and placebo group. However, FPG levels and triglyceride levels were significantly different between GTP and placebo group at baseline. In both of GTP and placebo group, there were no significant change after 12 weeks of treatment in FPG, HbA1c, total cholesterol, LDL cholesterol, triglyceride, levels of MDA, and GSHPx activities. SOD activities significantly increased after 12 weeks of treatment in both of GTP and placebo group. The increase of SOD activities were significantly higher in GTP group than in placebo group (P = 0.01).
CONCLUSIONS
Supplementation of green tea polyphenol increased antioxidant activity in type 2 diabetic patients. The effect on plasma glucose and lipid level was not significant but should be confirmed in further large scaled studies.

Keyword

Antioxidant; Lipid; Glucose; Green tea polyphenol; Type 2 Diabetes Mellitus

MeSH Terms

Blood Glucose*
Body Mass Index
C-Peptide
Cholesterol
Cholesterol, HDL
Cholesterol, LDL
Diabetes Mellitus, Type 2
Fasting
Glucose
Glutathione Peroxidase
Guanosine Triphosphate
Humans
Hypoglycemic Agents
Liver Function Tests
Malondialdehyde
Models, Animal
Plasma*
Superoxide Dismutase
Tea*
Triglycerides
Blood Glucose
C-Peptide
Cholesterol
Cholesterol, HDL
Cholesterol, LDL
Glucose
Glutathione Peroxidase
Guanosine Triphosphate
Hypoglycemic Agents
Malondialdehyde
Superoxide Dismutase
Tea

Figure

• 

  Fig. 1 Changes in superoxide dismutase activities after 12 weeks treatment of green tea polyphenol or placebo. There were significant differences between baseline and after 12 weeks of treatment in both placebo group and green tea polyphenol group (P < 0.05 by paired-t test). *There was a significant difference between placebo and green tea polyphenol group (P = 0.11 by repeated measure general linear models).

Reference

1. Khokhar S, Magnusdottir SG. Total phenol, catechin, and caffeine contents of teas commonly consumed in the United kingdom. J Agric Food Chem. 2002. 50:565–570.

2. Higdon JV, Frei B. Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions. Crit Rev Food Sci Nutr. 2003. 43:89–143.

3. Hyon SH, Kim DH. Long-term preservation of rat pancreatic islets under physiological conditions. J Biotechnol. 2001. 85:241–246.

4. Crespy V, Williamson G. A review of the health effects of green tea catechins in in vivo animal models. J Nutr. 2004. 134:3431S–3440S.

5. Frei B, Higdon JV. Antioxidant activity of tea polyphenols in vivo: evidence from animal studies. J Nutr. 2003. 133:3275S–3284S.

6. Giugliano D, Ceriello A, Paolisso G. Oxidative stress and diabetic vascular complications. Diabetes Care. 1996. 19:257–267.

7. Cai H, Harrison DG. Endothelial dysfunction in cardiovascular diseases: the role of oxidant stress. Circ Res. 2000. 87:840–844.

8. Brownlee M. Biochemistry and molecular cell biology of diabetic complications. Nature. 2001. 414:813–820.

9. Nishikawa T, Edelstein D, Du XL, Yamagishi S, Matsumura T, Kaneda Y, Yorek MA, Beebe D, Oates PJ, Hammes HP, Giardino I, Brownlee M. Normalizing mitochondrial superoxide production blocks three pathways of hyperglycaemic damage. Nature. 2000. 404:787–790.

10. Ceriello A. New insights on oxidative stress and diabetic complications may lead to a "causal" antioxidant therapy. Diabetes Care. 2003. 26:1589–1596.

11. Yusuf S, Dagenais G, Pogue J, Bosch J, Sleight P. Vitamin E supplementation and cardiovascular events in high-risk patients. The Heart Outcomes Prevention Evaluation Study Investigators. N Engl J Med. 2000. 342:154–160.

12. Heart Protection Study Collaborative Group. MRC/BHF Heart Protection Study of antioxidant vitamin supplementation in 20,536 high-risk individuals: a randomised placebo-controlled trial. Lancet. 2002. 360:23–33.

13. de GG. Low-dose aspirin and vitamin E in people at cardiovascular risk: a randomised trial in general practice. Collaborative Group of the Primary Prevention Project. Lancet. 2001. 357:89–95.

14. Fraga CG, Leibovitz BE, Tappel AL. Lipid peroxidation measured as thiobarbituric acid-reactive substances in tissue slices: characterization and comparison with homogenates and microsomes. Free Radic Biol Med. 1988. 4:155–161.

15. Marklund S, Marklund G. Involvement of the superoxide anion radical in the autoxidation of pyrogallol and a convenient assay for superoxide dismutase. Eur J Biochem. 1974. 47:469–474.

16. Paglia DE, Valentine WN. Studies on the quantitative and qualitative characterization of erythrocyte glutathione peroxidase. J Lab Clin Med. 1967. 70:158–169.

17. M C S, K S, Kuttan R. Anti-diabetic activity of green tea polyphenols and their role in reducing oxidative stress in experimental diabetes. J Ethnopharmacol. 2002. 83:109–116.

18. Kao YH, Hiipakka RA, Liao S. Modulation of endocrine systems and food intake by green tea epigallocatechin gallate. Endocrinology. 2000. 141:980–987.

19. Waltner-Law ME, Wang XL, Law BK, Hall RK, Nawano M, Granner DK. Epigallocatechin gallate, a constituent of green tea, represses hepatic glucose production. J Biol Chem. 2002. 277:34933–34940.

20. Kim MJ, Ryu GR, Chung JS, Sim SS, Min dS, Rhie DJ, Yoon SH, Hahn SJ, Kim MS, Jo YH. Protective effects of epicatechin against the toxic effects of streptozotocin on rat pancreatic islets: in vivo and in vitro. Pancreas. 2003. 26:292–299.

22. Kreydiyyeh SI, bdel-Hasan BE, Churukian ZM. Tea extract inhibits intestinal absorption of glucose and sodium in rats. Comp Biochem Physiol C Pharmacol Toxicol Endocrinol. 1994. 108:359–365.

23. Mustata GT, Rosca M, Biemel KM, Reihl O, Smith MA, Viswanathan A, Strauch C, Du Y, Tang J, Kern TS, Lederer MO, Brownlee M, Weiss MF, Monnier VM. Paradoxical effects of green tea (Camellia sinensis) and antioxidant vitamins in diabetic rats: improved retinopathy and renal mitochondrial defects but deterioration of collagen matrix glycoxidation and cross-linking. Diabetes. 2005. 54:517–526.

24. Hosoda K, Wang MF, Liao ML, Chuang CK, Iha M, Clevidence B, Yamamoto S. Antihyperglycemic effect of oolong tea in type 2 diabetes. Diabetes Care. 2003. 26:1714–1718.

25. Nakachi K, Matsuyama S, Miyake S, Suganuma M, Imai K. Preventive effects of drinking green tea on cancer and cardiovascular disease: epidemiological evidence for multiple targeting prevention. Biofactors. 2000. 13:49–54.

26. Sato Y, Nakatsuka H, Watanabe T, Hisamichi S, Shimizu H, Fujisaku S, Ichinowatari Y, Ida Y, Suda S, Kato K. Possible contribution of green tea drinking habits to the prevention of stroke. Tohoku J Exp Med. 1989. 157:337–343.

27. Imai K, Nakachi K. Cross sectional study of effects of drinking green tea on cardiovascular and liver diseases. BMJ. 1995. 310:693–696.

28. Kono S, Shinchi K, Wakabayashi K, Honjo S, Todoroki I, Sakurai Y, Imanishi K, Nishikawa H, Ogawa S, Katsurada M. Relation of green tea consumption to serum lipids and lipoproteins in Japanese men. J Epidemiol. 1996. 6:128–133.

29. Muramatsu K, Fukuyo M, Hara Y. Effect of green tea catechins on plasma cholesterol level in cholesterol-fed rats. J Nutr Sci Vitaminol (Tokyo). 1986. 32:613–622.

30. Raederstorff DG, Schlachter MF, Elste V, Weber P. Effect of EGCG on lipid absorption and plasma lipid levels in rats. J Nutr Biochem. 2003. 14:326–332.

32. Maron DJ, Lu GP, Cai NS, Wu ZG, Li YH, Chen H, Zhu JQ, Jin XJ, Wouters BC, Zhao J. Cholesterol-lowering effect of a theaflavin-enriched green tea extract: a randomized controlled trial. Arch Intern Med. 2003. 163:1448–1453.

33. Sugiyama K, He P, Wada S, Saeki S. Teas and other beverages suppress D-galactosamine-induced liver injury in rats. J Nutr. 1999. 129:1361–1367.

34. Sung H, Nah J, Chun S, Park H, Yang SE, Min WK. In vivo antioxidant effect of green tea. Eur J Clin Nutr. 2000. 54:527–529.

35. van het Hof KH, de Boer HS, Wiseman SA, Lien N, Westrate JA, Tijburg LB. Consumption of green or black tea does not increase resistance of low-density lipoprotein to oxidation in humans. Am J Clin Nutr. 1997. 66:1125–1132.