Effects of chronic green tea flavonoid supplementation on features of metabolic syndrome, biomarkers of oxidative stress and inflammation and plasma catechin levels in subjects with metabolic syndrome

Abstract

Green tea, rich in anti-oxidants, particularly epigallocatechin gallate (EGCG), is inversely associated with cardio vascular disease (CVD). Metabolic syndrome (MeS) is linked with increased oxidative stress & inflammation and subsequent risk for CVD. The main objectives of the study are to examine the effects of green tea beverage and green tea extract supplementation on features of MeS, biomarkers of oxidative stress and inflammation and plasma catechin levels. Obesity has parallel association with metabolic syndrome and Oklahoma is the sixth most obese state with 30.3 % prevalence of obesity. Hence, green tea supplementation study will address this problem. 28 subjects with MeS were randomly assigned to control, green tea beverage (4 cups/day, 440 mg EGCG) or green tea extract (2 capsules/day, 460 mg EGCG) groups for 2 months. Chronic green tea supplementation for 8 weeks showed significant weight loss in green tea beverage group (-2.3 kg, p<0.05) vs control. This study found no significant difference in markers of oxidative stress and inflammation. However, there is a decreasing trend in Ox-LDL (- 19.7%, p<0.1), nitric oxide (- 31.2 %, p<0.1) levels and increasing trend in HDL cholesterol in beverage group vs control after 8 weeks of supplementation. Green tea catechins were found in plasma samples collected after over-night fast. This indicates that catechins may present in the system for longer periods of time. Green tea supplementation with higher doses for longer periods is necessary to explore the findings of our study.