THE EFFECTS OF BLACK TEA ON BLOOD LIPIDS AND CARDIOVASCUALR DISEASE RISK IN HUMANS

Authors: Harris, Gabriel; Baer, David; Clevidence, Beverly

Submitted to: International Symposium on Biocatalysis and Biotechnology: Functional Food and Industrial Products
Publication Type: Proceedings
Publication Acceptance Date: 6/28/2006
Publication Date: 7/28/2006
Citation: Harris, G.K., Baer, D.J., Clevidence, B.A. 2006. The effects of black tea on blood lipids and cardiovascualr disease risk in humans. International Symposium on Biocatalysis and Biotechnology: Functional Food and Industrial Products.

Interpretive Summary: Habitual intake of tea is widely believed to protect against cardiovascular disease due antioxidant and anti-inflammatory effects, improved vascular endothelial function, and reduced blood lipid concentrations. Yet few clinical trials have been conducted to determine the effects of black tea, the most widely consumed type of tea worldwide, on risk factors for cardiovascular disease. Thus, we assessed the effects of black tea consumption on lipid and lipoprotein concentrations and antioxidant status in mildly hypercholesterolemic adults (7 men and 8 women). Subjects consumed 5 servings of tea or a caffeine-free placebo beverage while consuming a controlled diet that maintained body weight. Treatments, blinded to subjects and investigators, were administered for 3 wk each in a crossover design. In a third period, caffeine was added to the placebo in an amount equal to that in the tea. Compared to the placebo beverage that contained no caffeine, tea consumption reduced total cholesterol 3.8% and LDL cholesterol 7.5%. Measures of oxidative status were unchanged. Thus black tea, as part of a healthy diet, reduces total and LDL cholesterol in mildly hypercholesterolemic adults by biologically significant amounts, and thus may reduce the risk of coronary heart disease. Black tea consumption did not affect measures of antioxidant status.

Technical Abstract: Habitual intake of tea is widely believed to protect against cardiovascular disease due antioxidant and anti-inflammatory effects, improved vascular endothelial function, and reduced blood lipid concentrations. Yet few clinical trials have been conducted to determine the effects of black tea, the most widely consumed type of tea worldwide, on risk factors for cardiovascular disease. Thus, we assessed the effects of black tea consumption on lipid and lipoprotein concentrations and antioxidant status in mildly hypercholesterolemic adults (7 men and 8 women). Subjects consumed 5 servings of tea or a caffeine-free placebo beverage while consuming a controlled diet that maintained body weight. Treatments, blinded to subjects and investigators, were administered for 3 wk each in a crossover design. In a third period, caffeine was added to the placebo in an amount equal to that in the tea. Compared to the placebo beverage that contained no caffeine, tea consumption reduced total cholesterol 3.8% and LDL cholesterol 7.5% whereas apolipoprotein B, lipoprotein(a), HDL cholesterol, apolipoprotein A-I and triglycerides were unchanged. Compared to the placebo beverage with caffeine, tea consumption reduced total cholesterol 6.5%, LDL cholesterol 11.1%, apolipoprotein B 5% and lipoprotein(a) 16.4%. Measures of oxidative status were unchanged and included oxidized LDL, F2-isoprostanes, urinary 8-hydroxy-2’-deoxyguanosine, ex vivo ferric ion reducing capacity and thiobarbituric acid reactive substances in LDL. Thus black tea, as part of a healthy diet, reduces total and LDL cholesterol in mildly hypercholesterolemic adults by biologically significant amounts, and thus may reduce the risk of coronary heart disease. Black tea consumption did not affect measures of antioxidant status.