It is commonly believed that polyphenol antioxidants, found in tea, have a variety of health benefits, including cardiovascular benefits. However, randomized trials to date have yielded mixed results on the effects of tea on cardiovascular risk factors.
To address inconsistencies in previous studies and to determine if there are effects of moderate tea drinking on cardiovascular risk factors, Kenneth J. Mukamal, M.D., M.P.H, M.A., and colleagues conducted a small, six-month, randomized clinical trial. The study included 28 adults, 55 years and older, who were at an increased risk for cardiovascular disease.
Researchers compared two groups of 14 participants, who were assigned to drink three glasses daily of either a standardized black tea preparation or water. After six months, research data showed that there were no significant differences between the tea group and the water group on advanced cardiovascular risk biomarkers, such as metabolic factors, lipid levels, markers of inflammation, and systolic blood pressure.
It should be noted that not all pathways to cardiovascular disease were measured in the study. Also, although the black tea used in the study contained ample polyphenol content, doses given to participants were smaller than in some previous studies. The researchers believe their study is the longest such trial conducted to date, but concluded that confirmation of the effects of black tea on cardiovascular risk will require larger and longer studies in more diverse populations.
Kenneth J. Mukamal, M.D., M.P.H., M.A., Kristen McDermott, R.N., Joe A. Vinson, Ph.D., et al. A 6-Month Randomized Pilot Study of Black Tea and Cardiovascular Risk Factors. American Heart Journal..2007