| Scope and method of study. Green tea, rich in flavonoids, has been shown to possess cardiovascular health benefits. This is a randomized controlled trial investigating whether green tea beverage or extract supplementation improved the cardiovascular risk profile associated with metabolic syndrome (MetS). Subjects with MetS were matched for age and sex and were randomly assigned to control (4 cups water/day), green tea (4 cups/day), or green tea supplement (2 capsules & 4 cups water/day) group for 8 weeks. Fasting blood samples, anthropometric measurements, and 3-day food records were taken at screening, 4 & 8 weeks. Blood samples were analyzed for lipid and glucose levels using standard clinical chemistry techniques. Dietary data were analyzed for nutritional content using Nutritionist Pro, version 3.2.;Findings and conclusions. Daily supplementation of decaffeinated green tea (4 cups/day) may be beneficial to humans diagnosed with the metabolic syndrome (MetS), as it may help decrease total body weight. Body weight and BMI decreased significantly (p<0.05) in green tea (-2.5 kg and -0.9, respectively) versus control (+0.6 kg and + 0.2 kg) at eight weeks. Although the supplement group did not reach significance, a similar weight loss trend was observed (-1.3 kg), which also decreased BMI (-0.4). When compared to controls, there were no significant differences in change at eight weeks for the green tea beverage or supplement group in fasting plasma glucose levels, lipid levels, body fat percentage, waist circumference, or blood pressure. However, a decrease in trend (p<0.1) of diastolic blood pressure at eight weeks for the green tea group (-4.7 mmHg) compared to placebo (+1.5 mmHg) was noted, and the same trend did not exist for the supplement group. An increase in trend (p<0.1) was observed for HDL cholesterol in green tea (+0.9 mg/dL) versus control (-1.4 mg/dL). A similar pattern was true for the supplement group (+0.6 mg/dL). At eight weeks, carbohydrate intake was significantly higher (p<0.05) for the green tea group (+67 g) versus control (-31 g). The supplement group exhibited a similar trend, (+24 g), suggesting possible carbohydrate malabsorption in both the green beverage and supplement groups. Thus, green tea beverage or supplements may be a beneficial tool to aid weight loss. Additional research, including longer study duration and larger sample size, is needed to confirm benefits such as a decrease in diastolic blood pressure and increase in HDL cholesterol with green tea flavonoid supplementation. |
