Black Tea and Heart Disease

Why are we studying black tea?
Several studies have suggested those individuals with a high intake of tea have a decreased risk for heart disease. Tea and certain foods and beverages (red wine, apples, and onions) contain antioxidant compounds called flavonoids. We believe that these antioxidants may prevent heart disease by protecting cells in blood vessels, including the endothelium.

What is the endothelium?
The endothelium is the inner lining of cells in blood vessels. It performs functions essential to these vessels including the regulation of blood clotting by releasing a number of factors including nitric oxide. We are able to measure how well the endothelium works by using ultrasound and other techniques to assess blood vessel dilation.

What happens to the endothelium in atherosclerosis?
In atherosclerosis, release of nitric oxide from endothelial cells is impaired. Since nitric oxide produces vasodilation and prevents platelet clumping, this abnormality may increase the risk for blood clot formation and vasospasm in the of the heart and brain. These abnormalities may lead to heart attack, stroke, and/or sudden death.
We believe that antioxidants in tea may improve the release of nitric oxide from the endothelium and thereby reduce the risk of cardiovascular disease.

What does the study involve?
During this study you will be asked to drink 6 cups (150ml or about 5oz each) of brewed regular black tea per day for one month and six cups of spring water per day for one month. You will be asked not to drink any other tea or coffee during the two-month study period. You will also be asked not to drink red wine during the study. The tea and water will be provided to you in jars and we will ask you to return the empty jars to us so that we may monitor how much tea was consumed. You may drink the tea hot, cold, or on ice with any additives at any time during the day or evening. During the study you will be asked to make 3 visits to the Coronary Health Unit at the East Newton Street Campus of Boston Medical Center.

Who is eligible for the study?
To be eligible for the study, you must have proven coronary artery disease (by angiogram, history of a heart attack, or a positive stress test). You cannot be taking regular antioxidant supplements including vitamin E and vitamin C.

What are the risks involved?

Tea consumption will increase urine production and may make you feel jittery. The tea may also keep you awake at night, particularly if the tea is consumed in the evening. If you have had any significant provlenms with tea or coffee in the pase, you will not be eligible for the study. We will also be taking a small blood sample during the study which may cause temporary discomfort and/or the chance of a slight bruise.

Who do I contact to participate?