A 6-month randomized pilot study of black tea and cardiovascular risk factors

Abstract

Background: The effects of black tea consumption on cardiovascular risk factors have been inconsistent in previous randomized trials, all of which have been limited to a few weeks duration.

Methods: We conducted a pilot parallel-design randomized controlled trial among 31 adults aged 55 years and older with either diabetes or 2 other cardiovascular risk factors but no established clinical cardiovascular disease. Participants were randomized to drink 3 glasses daily of either a standardized black tea preparation or water for 6 months. Cardiovascular risk factors were measured at the beginning and conclusion of the study.

Results: Three participants dropped out of the study, leaving 14 participants assigned to tea and 14 assigned to water eligible for analyses. We found no statistically significant effects of black tea on cardiovascular biomarkers, including lipids, inflammatory markers, hemoglobin, adhesion molecules, prothrombotic and fibrinolytic parameters, and lipoprotein oxidizability. Assignment to tea did not appreciably influence blood pressure, and heart rate among participants assigned to tea was marginally higher than among control participants at 3 months (P = .07) but not 6 months.

Conclusions: In this randomized trial of black tea intake over 6 months among older adults with known cardiovascular risk factors, black tea did not appreciably influence any traditional or novel biomarkers of cardiovascular risk. Longer randomized trials are needed to verify the inverse association of tea with risk of cardiovascular disease seen in cohort studies and identify potential candidate mechanisms for such an association.

Conflict of interest statement

Conflict of Interest

We have cited potential conflicts of interest in the manuscript. Funding for this study was received entirely from the AHA and NCCAM. Templar Foods supplied bulk tea at no charge but provided no other support or funding, had no access to data, and had no involvement with drafting of the manuscript, interpretation or analysis of data, or submission of the manuscript. Dr. Vinson has received previous research funding from Lipton and other food manufacturers for research unrelated to this study.

Figures

Figure 1

CONSORT flowchart of participants in the TEA Pilot Study.

Figure 2

Systolic blood pressure and heart rate according to tea or water assignment. Means with standard errors are shown.