The very famous green tea is mainly the extract of the leaves of “Camellia sinensis”. Its origin is from China where a recent extended study was concluded showing that drinking green tea can protect the human organism from developing Type 2 diabetes. In particular, such protective properties of the green tea were obeserved in individuals who drank 16 to 30 cups of tea a week (Huang H, PloS One. 2013 Nov).
The biologically active molecules found in green tea, are called catechins and the most active of them is the epigallocatechin EGCG which is thought to mimic in way the action of insulin (Anton S, CellSiqnal. 2007 Feb).
In placebo controlled studies in Type 2 diabetic patients who were not receiving insulin, green tea rich in catechins (> 580mg) was administered for 3 months. During the 12th week of the study it was observed that the waistline of patients who have been drinking green tea had declined comparing to those who did not follow the treatment. Also the levels of adiponectin, a hormone produced by fat cells of the body having antidiabetic activity, was significantly increased only in those who have been drinking green tea rich in catechins (Nagao TObesity, Silver Spring, 2009 Feb). Αlmost the same results were presented in another clinical investigation where the waistline was again reduced in patients who received continuously 1,500 mg green tea extract decaffeinated for 16 weeks. In those patients, the green tea appears to be helpful in the management of diabetes and small reductions were observed in glycosylated hemoglobin (Hsu CH, Altern Med Rev. 2011 Jun). Such reductions in glycosylated hemoglobin were observed in other clinical studies, this time in pre-diabetic volunteers who consumed green tea extract rich in catechins (456 mg) daily for 2 months (Fukino Y, Eur J Clin Nutr. 2008).
Although reductions in the area of the waistline are associated with reductions of weight is the most common beneficial effect of the consumption of decaffeinated green tea, even on elderly patients with metabolic syndrome (Vieira Senger AE, J Nutr Health Aging. 2012), there has been also observed a tslight reduction of high blood pressure as another positive effect from which diabetic and no-diabetic people can benefit.
So when slightly hypertensive patients were drinking three cups of green tea daily for four weeks both the systolic and diastolic pressure of the blood decreased noticeably (Mozaffari-Khosravi H, J Diet Suppl. 2013 Jun.). Almost identical were the results (reduction of blood pressure) in pre-diabetic and women who consumed 3 cups of green tea daily for 14 weeks. Very interesting is the fact that in this study, green tea has managed to reduce the levels of liver enzymes (aminotransferases) in women (Toolsee NA, Biomed Res Int. 2013).