Short-term Effects of Green Tea on Blood Pressure, Endothelial Function, and Metabolic Profile in Obese Prehypertensive Women: A Crossover Randomized Clinical Trial

Abstract

Background: Green tea consumption has been inversely associated with cardiovascular disease (CVD) in epidemiological studies. Although some interventional trials suggest that green tea has beneficial effects on CVD risk factors, such as hypertension and obesity, others have failed to show such benefits.

Aims: To evaluate the short-term effects of green tea on blood pressure, endothelial function, metabolic profile, and inflammatory activity in obese prehypertensive women.

Methods: This study was a crossover, randomized, double-blind, placebo-controlled clinical trial. Participants were randomly allocated to receive daily 3 capsules containing either 500 mg of green tea extract (GTE) or a matching placebo for 4 weeks, with a washout period of 2 weeks between treatments. Each GTE capsule contained 260 mg of polyphenols. At the beginning and at the end of each treatment, participants were submitted to evaluation of blood pressure (ambulatory blood pressure monitoring, ABPM), endothelial function (Endo-PAT 2000 and cellular adhesion molecules), nutritional parameters, metabolic profile, and biomarkers of inflammation.

Results: Twenty women age 41.1 ± 8.4 years completed the study. After 4 weeks of GTE supplementation in comparison with placebo, there was a significant decrease (p < 0.05) in systolic blood pressure at 24 hours (−3.61 ± 1.23 vs 1.05 ± 1.34 mmHg), daytime (−3.61 ± 1.26 vs 0.80 ± 1.57 mmHg), and nighttime (−3.94 ± 1.70 vs 1.90 ± 1.66 mmHg). Changes in diastolic blood pressure and in all other parameters did not present a significant difference between GTE and placebo.

Conclusion: The findings of this study suggest that in obese prehypertensive women, short-term daily intake of GTE may decrease blood pressure.

Key words:

• green tea
• blood pressure
• obesity
• metabolic profile
• endothelial function

ACKNOWLEDGMENTS

The authors express their sincere gratitude to Maria de Lourdes Guimarães Rodrigues and Débora Cristina Torres Valença.

Funding

The present study was supported by Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ).