Tea drinkers in studies see cardiovascular benefits

23 May 2012By World Tea News

Two independent studies suggest flavonoids and polyphenols found in tea may aid in the prevention of heart disease.

Consumption of the flavonoid rutin in foods and tea could help to prevent the formation of blood clots, according to researchers at the Beth Israel Deaconess Medical Center at Harvard Medical School.

The report published in the Journal of Clinical Investigation reveals that the compound commonly found in fruits and vegetables could have promise in blocking the formation of blood clots in an animal model of clotting (thrombosis)

“Rutin proved to be the most potently anti-thrombic compound that we ever tested in this model,” said lead researcher Robert Flaumenhaft. In particular, he revealed that rutin was shown to inhibit both platelet accumulation and fibrin generation during clot formation.

Clots occur in both arteries and veins, he explained. Arteries are platelet-rich while those in veins are fibrin-rich. This discovery suggests that a single agent can treat and prevent both types of clots,” he said. The researcher recommended clinical trials.

Results show rutin may prove helpful in the prevention and treatment of stroke, heart attack, pulmonary embolism and deep vein thrombosis.

A different study to examine the impact of tea drinking on blood cholesterol levels found black tea intake improves lipid profile and antioxidant status of a random population.

In a paper published in the Journal of Preventative Medicine, researchers studied the effect of black tea on risk factors of cardiovascular disease in a normal population.

In a report included in the American Botanical Council’s HerbClip “the moderate intake of black tea improved the plasma levels of some of the cardiovascular disease risk factors and total antioxidant capacity.”

"Although the underlying biological mechanisms for these effects and the exact role of phenolics warrant an extensive study, tea may provide an important source of dietary antioxidants in many individuals," conclude the authors.

They conducted a randomized, controlled, parallel clinical trial to determine the effects of black tea consumption on fasting serum glucose, total cholesterol (TC), triglycerides (TGs), high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol, as well as the antioxidant status in a normal population in the Republic of Mauritius.

Participants were given three 200mL servings of tea daily with no additives for 12 weeks, then drank hot water to wash out their systems. Black tea was from the Mauritius Corson Tea Estate Co. was carefully analyzed to determine the concentration of flavonoids.

Subjects tested after 12 weeks of tea drinking showed significantly increased HDL (good) cholesterol levels: 17% in the men and 24% in the women.

A significant increase in antioxidant activity was in tea-treated men (440% FRAP) and tea-treated women (386% FRAP) at week 12, followed by a significant increase in the men during the washout. The tea’s antioxidant effect was also measured in TEAC values which were slightly reduced by tea intake in the men and women at week 12.

Tea also appears to have a beneficial impact on glycemic levels. The mean fasting blood glucose level at baseline was 134 ± 66 mg/dL for the men and 111 ± 38 mg/dL for the women. At 12 weeks, those levels dropped significantly for the men (30.2%) and for the women (14.8%). Non-significant decreases were observed in the control groups.

The population of Mauritius has an unusually high (23.6%) incidence of diabetes compared to populations worldwide. The authors note that the baseline glycemic levels in both the control and test groups were higher than the international standard values. Examining the results of this trial, the authors conclude that "an antihyperglycemic effect of black tea can therefore be anticipated."