An Overview of Research on the Potential Health Benefits of Tea



Human population studies have found that people who regularly consume three or more cups of Black Tea per day have a reduced risk of heart disease and stroke. Clinical studies suggest that the risk reduction associated with Black Tea consumption may be due to improvement in some risk factors for cardiovascular disease, including cholesterol levels, blood vessel function and a reduction in oxidative damage.

While researchers are still examining the various mechanisms by which tea flavonoids function, some studies suggest multifunctional mechanisms, meaning that several mechanisms work in tandem to collectively improve markers for cardiovascular health. Important areas of tea and cardiovascular health research include blood vessel and endothelial function, or the ability of the blood vessels to dilate to allow for proper blood flow, serum cholesterol levels and Low Density Lipoprotein (LDL) cholesterol oxidation. Each of these factors impact the risk of myocardial infarctions (heart attacks), stroke and cardiovascular disease. Study findings in the area of tea and the reduction in cardiovascular disease risk include the following:

Coronary Heart Disease (CHD)

  • A total of 3,430 men and women aged 30-70 years from the Saudi Coronary Artery Disease Study were examined and 6.3 percent were found to have indications of coronary heart disease (CHD). The researchers found that those who drank more than six cups of tea per day (>480 mg) had significantly lower prevalence of CHD than non-tea drinkers, even after adjustment for risk factors like age and smoking9. The researchers also found that drinking six or more cups of Black Tea per day was associated with decreased serum cholesterol and triglyceride concentrations.
  • Dutch researchers found that study participants who drank one to two cups of Black Tea daily had a 46 percent lower risk of severe aortic atherosclerosis, a strong indicator of cardiovascular disease. Those who drank more than four cups of tea a day had a 69 percent lower risk10.

Cardiac Events

  • The Zutphen study, which assessed 805 male subjects over a period of five years, found that the incidence of fatal and nonfatal first myocardial infarction and mortality from stroke decreased significantly as intake of flavonoids, derived mainly from tea, increased in a dose-dependent manner2. A follow-up to this study found that high intake of flavonoids significantly lowered the risk of stroke in study participants3.
  • A Harvard study examined 340 men and women who had suffered heart attacks and compared them to matched control subjects. They found that those who drank a cup or more of Black Tea daily had a 44 percent reduction in the risk of heart attack compared to non-tea drinkers11.
  • Another recent Harvard study of 1,900 people found that those who consumed tea during the year prior to a heart attack were up to 44 percent more likely to survive over the three to four years following the event. Those who consumed fewer than 14 cups of tea per week experienced a 28 percent reduced death rate and those who consumed more than 14 cups of tea per week were found to have a 44 percent reduced death rate, as compared to non-tea drinkers12.
  • o A recent meta-analysis discovered that consumption of three cups of tea per day was associated with an estimated decrease of 11 percent in the incidence of myocardial infarction, or heart attack14.


Researchers from the United States Department of Agriculture (USDA) studied the effect of tea on 15 mildly hypercholesterolemic adult participants following a "Step I" type diet moderately low in fat and cholesterol, as described by the American Heart Association and the National Cholesterol Education Program. After three weeks, researchers found that five servings of Black Tea per day reduced LDL ("bad") cholesterol by 11.1 percent and total cholesterol (TC) by 6.5 percent compared to placebo beverages15.

Other CVD Risk Factors

  • A recent clinical study showed that short- and long-term consumption of Black Tea by subjects with coronary artery disease restored endothelial and blood vessel function to levels similar to that of healthy subjects16. Endothelial function is the ability of the inner lining of blood vessels to dilate in response to increased blood flow.
  • Another clinical study found that regular ingestion of tea resulted in a significant and consistent increase in endothelium-dependent and endothelium-independent blood vessel dilation17. Subjects with mild elevations in serum cholesterol or triglyceride concentrations consumed either five cups of Black Tea per day for four weeks or hot water. The researchers hypothesized that one mechanism for the apparent beneficial effects of tea on cardiovascular health could be this improved vasodilator function.
  • An in vitro study found that Green Tea polyphenols inhibit the proliferation of aortic smooth muscle cells to prevent the development of atherosclerosis18.
  • In vitro studies have shown that tea flavonoids protect low-density lipoproteins from oxidation, inhibit plasma lipid peroxidation, platelet aggregation and thromboxane formation - all factors important for maintaining a healthy circulatory system19,20. Studies in animals are promising, but human studies conducted to date on the effect of tea consumption on LDL oxidation are inconclusive.