A large body of scientific evidence indicates the benefits of tea drinking for its wide range of medicinal properties. Tea prevents coronary heart disease, hypertension, blood sugar and tooth decay. Tea has also been reported to have antiviral and germicidal activity.
The most important medicinal value of tea is that it is anticarcinogenic and antimutagenic. The anticarcin ogenic activity contributed by the antioxidant polyphenols in tea has been shown to be in very low concentration even in consumer dosages. Thus tea offers tremendous scope of emerging as practical chemipreventive included in a healthy diet for protection of the general consumers by lowering the risk of different types of cancer.
Tea Research Association (TRA), Tocklai in collaboration with Indian Institute of Chemical Biology (IICB), Kolkata has carried out studies on health aspects of black tea. In these studies, the influence of tea in totality was examined rather than evaluating isolated fractions. Results indicated the following:
- Regular administration of low dose of black tea extracts (0.002-0.2%) significantly reduced the total cholesterol levels in rats.
- Normal rates of black tea extracts significantly reduced the trigycerides levels.
- The level of HDL (high density lipids) was increased though not significantly.
- The levels of VLDL (very high density lipids) and LDL (low density lipids)showed a slight decrease but the effect was not significant.
Thus the results indicated that chronic administration of black tea is capable of reducing the total cholesterol and triglyceride levels in healthy animals. The flavonoids in tea prevent oxidation of LDL cholesterol.
In another study effect of black tea consumption on diabetes mellitus was evaluated. Consumption of black and green tea could not only prevent the experimentally induced diabetes but was also found to be effective in curing diabetes induced by streptozotocin in rats.
The effect of black tea consumption on liver function was examined by monitoring the levels of SGOT (serum glutamic oxolacetic transaminase) and SGPT (serum glutamic pyruvic transaminase) in experimental hepatoxicity induced rats. Results indicated that consumption of black or green tea had no adverse effect on liver function in the experimental animals.
The influence of tea on muscular function was studied by examining the effect of hot water brew of black or green tea on the mammalian skeletomotor apparatus. Black tea extract produced a concentration dependent facilitation of muscle contraction induced by nerve stimulation.
The effect of tea consumption on experimentally induced gastric ulcer in rats was also carried out. Tea extracts was most effective in preventing ulcers induced by aspirin, indomethacine, cold resistant stress and reserpine.
Further studies on health aspects of tea are in progress.
Principal Components of Black Tea Beverage
|Phenolic acids and Depsides||
(Components measured in wt % of extracted solids)