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United States Department of Agriculture

Agricultural Research Service

Research Project: Dietary Guidelines Adherence and Healthy Body Weight Maintenance Title: Effect of black tea intake on blood cholesterol concentrations in individuals with mild hypercholesterolemia: A diet-controlled randomized trial

Authors
item Troup, Rasa -
item Hayes, Jennifer -
item Raatz, Susan
item Thyagarajan, Bharat -
item Khaliq, Waseem -
item Jacobs, David -
item Key, Nigel -
item Morawski, Bozena -
item Kaiser, Daniel -
item Bank, Alan -
item Gross, Myron -

Submitted to: Journal of the Academy of Nutrition and Dietetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 7, 2014
Publication Date: N/A

Interpretive Summary: Habitual intake of black tea has been associated with lower serum cholesterol concentrations in observational studies. However, clinical trials have had inconsistent results. We studied the effect of black tea on cholesterol concentrations in 57 (32 men and 25 women) mildly hypercholesterolemic under controlled conditions. Participants completed a 15-week, double blind, randomized crossover trial, during which they consumed a controlled low-flavonoid diet plus 5 cups of black tea or a tea-like placebo over two 4-week treatment periods. At the end of the trial period, no differences were statistically or clinically significant in cholesterol, HDL or LDL. Thus, the intake of 5 cups of black tea in combination with a low-flavonoid, typical American diet did not significantly alter the lipid profile of mildly hypercholesterolemic subjects.

Technical Abstract: Habitual intake of black tea has predominantly been associated with relatively lower serum cholesterol concentrations in observational studies. However, clinical trials evaluating the potential effects of black tea on serum cholesterol have had inconsistent results. These mixed results could be explained by several factors, in particular, uncontrolled confounding caused by lifestyle factors e.g. self-selected diets. The diet-controlled clinical trial presented herein provides estimates of the effect of black tea consumption on cholesterol concentrations in 57 (32 men and 25 women) mildly hypercholesterolemic individuals (total cholesterol concentrations between 4.9 and 6.7 mmol/L, 190 and 260 mg/dl), under tightly controlled conditions that minimize possible confounding. Participants completed a 15-week, double blind, randomized crossover trial, during which they consumed a controlled low-flavonoid diet plus 5 cups of black tea or a tea-like placebo over two 4-week treatment periods. The caffeinated placebo drink matched the color and taste of the tea, and did not contain any flavonoids. At the end of the trial period, differences in cholesterol concentrations between tea and placebo treatments were +1.64% for total cholesterol, -0.77% for low-density lipoprotein cholesterol (LDL-C), +1.40% for high-density lipoprotein cholesterol (HDL-C), +7.81% for triglycerides, -0.23% for LDL plus HDL cholesterol fraction, and -3.08% for LCL-C/HDL-C ratio. None of these differences were statistically or clinically significant. Thus, the intake of 5 cups of black tea in combination with a low-flavonoid, typical American diet did not significantly alter the lipid profile of mildly hypercholesterolemic subjects.

Last Modified: 12/21/2014
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