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According to the legend, in the ancient year of 2737 BC, a Chinese Emperor, Shen Nung, used to boil the drinking water above the open fire, believing that the people who drink boiled water are healthier. A few small leaves of Camelia sinensis flew into his cup by accident. The Emperor drank this mix and described it as a beverage that gives “strength to the body, pleasure to the mind, and purpose to the goal”.
Today, tea is the second most consumed beverage in the world, right after water, and people drink it warm, cold, herbal tea, with the addition of aroma, sugar, honey, milk, or without any additives at all.
In the recent years, tea has been intensively studied because of its beneficial effects on human health, and more and more studies are showing that the polyphenols, phytochemicals found in tea, can help to reduce the risks from certain chronic diseases of today. Catechins in the tea possess an array of pharmacological benefits: antioxidant, anti-mutagenic, anti-cancerogenic, and anti-inflammatory.
Types of tea
All teas are made from the same plant whose botanical name is Camelia sinensis. The differences between the teas are the result of the processing, growth conditions, and geographical position. Camelia sinensis or tea plant, originates from Asia, but it is currently being grown across the world in the tropical and subtropical areas. With over 3000 types, tea is the most consumed beverage in the world, right after water.
Tea can be divided into five basic categories: black, green, oolong, white, and Pu-erh.
It is allowed to dry the black tea in a process called oxidation (which is sometimes mistakenly called fermentation). Black teas are mostly completely exposed to oxidation, and the result is a characteristic dark brown and black color of the leaves; its taste is more prominent and robust than that of other teas; and it contains more caffeine than the other teas.
Out of all widely used types of tea, green tea has the most health arguments and it is highly recommended for the everyday intake. It is allowed to dry the green tea only after it has been picked. The oxidation that follows is a very short one and it is done by sudden heating. Being that it oxidizes in lower temperatures for shorter periods of time, green tea contains less caffeine.
For the Oolong tea production (also known as wulong tea), a partial oxidation is sufficient. The share of caffeine in this tea ranges somewhere between the black and green tea. Oolong’s taste is usually not as robust or subtle as that of the green tea, but it is intriguing and filled with rich, odoriferous tones. Very often, Oolong’s taste and smell reminds of fresh flowers and fruit.
White tea has the gentlest aroma. It is reputable because of its subtlety, complexity, and a naturally sweet taste, accompanied by the lowest levels of caffeine.
Pu-erh is an ancient Chinese black tea celebrated for its healing powers and earthy taste. It is, perhaps, the most mysterious of all teas. Until 1995, its import into USA was illegal, and the process of its production is a highly kept state secret in China. It is very strong, with an amazingly deep and rich taste, absent the bitterness.
Cold tea’s production began in Louisiana in 1904. According to the records, because of the working conditions that involved very high temperatures, the laborers who worked in its production turned to their product for refreshment. But, instead of drinking it warm, as it should be drank, they poured it over the ice-cubes and inadvertently created an idea for the production of a very popular and refreshing summer drink. That same year, the production of tea in filter bags began.
What does science say about tea?
The star of the greatest number of the scientific research that strives to discover the effect of tea on human health is the green tea. This is because green tea retains the most polyphenols, or molecules responsible for the positive effects of tea. A polyphenol which is considered to be the most powerful active substance in the green tea is epigallocatechin-3-galat (EGCG), a type of catechin.
Numerous studies have pointed to the positive effects of EGCG molecule on improvement of the blood cholesterol levels (lowering the level of the “bad” and increasing the level of the “good” cholesterol), as well as the reduced oxidation of the LDL (“bad”) cholesterol. In this manner, green tea prevents the appearance of various heart diseases.
The mixtures of green and black tea also prevent caries. This has been proven by the studies that were conducted on humans. In persons who have washed their mouths out with this tea extract, the creation of plaque was significantly reduced when compared to the ones who have not washed their mouths out with the tea extract.
Polyphenols in the green tea simultaneously stimulate the production of several types of the immune system cells and have antibacterial properties.
The majority of research that followed the improvement of health conditions is based on the amount of green tea that is being consumed in Asian countries – approximately 3 cups (750 ml) per day (which provides 240 – 320 mg of polyphenol). Nonetheless, some scientists suggest that more than 3 cups a day need to be consumed in order to achieve significant results.