Effects of Black and Green Tea Consumption on Blood Pressure and Liver Enzymes: A Randomized Controlled Trial

Background: The effect on tea consumption on blood pressure and liver enzymes are controversial. The beneficial effects of long-term ingestion of black and green tea on systolic and diastolic blood pressure have been suggested by several studies.Objectives: The overall goal of this study was to determine the effects of high tea consumption on blood pressure and liver enzymes.Design: We completed a 6-month randomized, controlled, double-blinded trial in a group of former and current smokers who were randomized to receive black or green tea preparations or a matching placebo.Results: A total of 146 participants (80 females and 66 males) were enrolled in the study. At the end of the 6-month intervention, women in the black tea group showed a 4 mmHg decrease (p = 0.01) in systolic blood pressure while female in the green tea group showed a 30.1% decrease (p = 0.035) in Alanine transaminase (ALT). No significant changes were observed in men.Conclusion: Our data confirm previous findings related to the beneficial effect of black tea on blood pressure and of green tea on serum liver enzymes especially among females. In addition, our study showed that long-term regular consumption of black tea and green is safe.