Drinking tea is becoming an international habit because of its health benefits. Countless researchers have concluded that those who drink tea are more likely to have better body conditions. Meanwhile, some scientist pointed out that tea also helps prevent cancer. Tea is a rich source of polyphenols called flavonoids, and a group of flavonoids in green tea, known as catechins, are really powerful antioxidants. During tea manufacturing (fermentation) process, catechins are transformed into theaflavins, which is another beneficial substance in tea. Black tea extract theaflavins too are potent antioxidants
When tea is oxidized (fermented), the catechins are converted into other chemicals: theaflavins and thearubigins. These chemicals are responsible for the darker color of black and more heavily-oxidized oolong teas. Theaflavins also contribute to the flavor and scent in tea. It’s an important chemical that distinguish green tea from black tea.
The theaflavins of black tea have been proved to be equally effective as antioxidants. There is a widespread public perception that antioxidants are beneficial to health, including organs, skin and hair. In a study conducted by a group of Chinese scientists, theaflavins were found to show strong qualities as antibiotics and antioxidants. However, some other scientists argued that theaflavins are not as effective as people think.
Although antioxidants have positive effects, they can also have negative effects on health as well. For example, antioxidants such as the theaflavins in black tea can bind to nonheme iron (the principal form of iron found in plant and dairy sources and in most nutritional supplements). Consumption of beverages rich in polyphenolic compounds, including black tea, peppermint tea, cocoa, and chamomile tea, has been shown to reduce the absorption of iron; in one study, 79-94% of the absorption was inhibited by black tea, and chamomile inhibited 47% of iron absorption.
A group of Chinese researchers in Beijing conducted a study on the medical effects of theaflavins. They applied theaflavins to rats with different diseases. After the research, they found that theaflavins improved cell activities throughout the body and helped protect heart cells by regulating oxidant activity. Rats that took theaflavins had better heart cells and better supply of oxygen. Therefore, they suggested people who suffer from arrhythmia drink some light black tea to improve their heart functions. Second, theaflavins can help reduce blood fat by reducing fat absorption. Third, theaflavins improve vascular relaxation and decrease the risk of getting arteriosclerosis. Arteriosclerosis is an essential cause of angiocardiopathy in China. In some areas of China, people have over-seasoned dishes, which lead to arteriosclerosis. Lacking exercise is another cause of arteriosclerosis too. Fat and sugar are over stored in their bodies. According to a study, 56.7% old people have arteriosclerosis in China. Forth, theaflavins can help restrain the reproduction of cancer cells. The reproduction of breast cancer cells in rats slow down after theaflavin injections. However, how theaflavins restrain cancer cells remains unclear. Fifth, theaflavins can also relieve the symptoms of diabetes. In Chinese medicine science, doctors suggest people witg diabetes to drink some tea after meals because it helps regulate blood sugar level.
Theaflavins can be found in other plants too, including cocoa beans. Theaflavins are common and abundant in plant sources, including fruits, vegetables, and herbal teas.
There has been some confusion whether or not adding milk to tea will block the health benefits of antioxidants in the tea. Scientists found contrary conclusions. Some studies found some convincing evidence that milk binds to certain antioxidants in the tea, thus preventing their absorption into the bloodstream. These results have been confirmed by measuring the level of catechins in the bloodstream. However, later work on black tea has found that the total antioxidant absorption, and the ability of the tea to prevent oxidative stress, is unaffected by adding milk.
In China, doctors recommend drinking pure tea (nothing added) for medical purpose. At the very least, having a cup of tea after meals helps to improve digestion and regulate blood sugar levels.