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Most people understand that Green Tea, and green tea supplements are good for us – but ask anyone why it is good for us, and they probably won’t have an answer. Indeed, it has long been general knowledge that green tea provides support to the human body – and this is backed up scientifically.
In this article, however, we will provide you with more substantial information – so that you can actually understand how green tea works, and exactly what it has been proven to do.
Popular belief dates the debut of tea as an aromatic, brewed drink to approximately 4,700 years ago in China. Today, while the story of the birth of tea remains unproven, the humble evergreen shrub has risen through the ranks to become the second most consumed beverage in the world after water.
Tea is made from the leaves of the same plant called Camellia sinensis. Based on the degree of fermentation of leaves, teas can be broadly classified into four different types: white tea, green tea, oolong tea and black tea.
- White tea white tea represents the least processed form of tea – the leaves and buds are simply dried or steamed and dried. White tea also contains a higher proportion of buds, which are covered with fine ‘silvery’ hairs that impart a light white/grey colour to the tea leaves.
- Green tea is unfermented. In order to ensure that the freshly picked leaf does not oxidise, before the tea is rolled, the leaf is either pan fried, or steamed. This kills the fermentation enzymes so no further fermentation take place. That is why the leaves are green, the liquor is light and the flavour is mild.
- Oolong tea is partially fermented. Leaves are picked and allowed to ferment for four or five hours in direct sunlight. Next, firing halts fermentation when it is half complete. Therefore, the leaves and the liquor have more color than for green, but not as dark as black tea. Some amazing fruit or flowery notes are trademarks of oolongs flavours.
- Black tea is fully fermented. Leaves are withered for about 15-18 hours to reduce moisture after picking. Then they are allowed to fully ferment before firing. The resulting leaves and liquor are usually darker than an oolong.
Green tea is manufactured in the following stages:
- Panfiring or Steamingoccurs immediately after the leaves are plucked. Green tea manufacture generally follows two methods of manufacturing – the Chinese method involves pan firing whereas the Japanese method follows steaming of the tea leaves. In panfiring process, the leaves are placed in a metal pan over a hot flame to render them soft and pliable. Alternatively, the tea leaves can be steamed. The sudden exposure to heat destroys enzymes that would otherwise lead to oxidation. The tea leaves are then cooled to room temperature before they go to the next phase in processing.
- Rolling is the next stage. Though traditionally this process was done with fingers and palms, nowadays, modern machinery is available for this process. Under pressure, the tea leaves are rolled and the leaf juice extracted is coated uniformly on the rolled leaf. In some processes the half rolled leaves are partially dried and rolled again.
- Firing involves drying of rolled leaf in large mechanical dryers. This reduces the moisture content of the leaf and increases shelf life. Fired green tea retains only 2% of its moisture.
China and Japan produce some of the finest green tea in the world. In addition, countries like India, Sri Lanka and Taiwan are also known to produce green tea of very high quality.
Green tea is naturally rich in antioxidants called polyphenols. The polyphenols present in green tea are un-oxidised polyphenols and are called catechins. These polyphenols exhibit very high antioxidant properties and help our body to fight various disease conditions. The antioxidants acts as free radical scavengers and keeps our system free of damaging free radicals.
Black Tea is a rich source of antioxidants called flavonoids. On a per cup basis, green tea delivers approximately 30% more antioxidants than black tea, assuming equal quantities of teas are used and brewing method is similar. Vitamin A, Vitamin C and Vitamin E, commonly known as ACE vitamins and which act as scavengers of free radicals are also present in both green and black tea.
One cup of green tea contains approx. 200mg of flavonoids. Studies indicate having three cups a day over 2 weeks increases flavonoid levels in the blood by 25%. While we now know that green tea is very healthy, more evidence is needed to understand how much green tea one must consume to really derive complete health benefits. This is because no two human beings are alike, and each one needs different levels of antioxidants depending on lifestyle, dietary habits, exposure to environmental factors like pollution, etc. All that can be said with some degree of confidence is that green tea is healthy!
Free radicals are very reactive natural chemical molecules present in our bodies that are unstable and hence cause damage to the cellular structure in our bodies through reaction with organic molecules present in our system. This process leads to cell damage and can even cause death of cells in our bodies.
Free radicals are always present in our bodies, but are kept in check under normal circumstances. Medical evidence suggests a linkage of excessive quantities of free radicals in the body to ageing and the onset of serious disorders like cancer and heart diseases.
Some free radicals arise normally during metabolism and some are created purposefully to neutralize viruses and bacteria. However, environmental factors such as pollution, radiation, and cigarette smoke can also spawn free radicals.
Normally, the body can handle free radicals through its own defence mechanism and presence of natural antioxidants. As the body progress in age, the body’s own defence mechanism is weakened and the concentration of antioxidants decreases. In such a situation, external supply of antioxidants is required to keep the defence mechanism active. If free radicals become excessive, damage can occur. Of particular importance is that free radical damage accumulates with age.
A Chemical Understanding of how Free Radicals are formed
The building blocks of human cells are atoms which consist of a nucleus, neutrons, protons and electrons. Electrons (negatively charged particles) are involved in chemical reactions and are the substance that bonds atoms together to form molecules.
The chemical behaviour of an atom is determined by the number of electrons in its outer shell. Because atoms seek to reach a state of maximum stability, an atom will try to fill its outer shell by:
- Gaining or losing electrons to either fill or empty its outer shell
- Sharing its electrons by bonding together with other atoms in order to complete its outer shell
Free Radicals are molecules with an odd, unpaired electron. These are very unstable and react quickly with other compounds, trying to capture the needed electron to gain stability. Generally, free radicals attack the nearest stable molecule, “stealing” its electron. When the “attacked” molecule loses its electron, it becomes a free radical itself, beginning a chain reaction. Once the process is started, it can cascade, finally resulting in the disruption of a living cell.
Antioxidants are natural chemical substances that prevent oxidative damage by free radicals by preventing them from damaging healthy cells. Antioxidants act as shields or barriers to prevent the invading free radicals from doing harm to cells
A Chemical Understanding of how Antioxidants fight free radicals
Antioxidants neutralize free radicals by donating one of their own electrons, ending the electron-“stealing” reaction. The antioxidant nutrients themselves don’t become free radicals by donating an electron because they are stable in either form.
Vitamin E is the most abundant fat-soluble antioxidant in the body and Vitamin C is the most abundant water-soluble antioxidant in the body. Vitamin C is of particular note in combating free-radical formation caused by pollution and cigarette smoke. Other common antioxidants are Vitamin E and Beta-carotene.
Vitamins A and C are well-known antioxidants, yet their effectiveness is nothing compared to a group of naturally-occurring phenolic compounds called flavonoids. Normal black tea is a rich source of flavonoids. Green Tea is rich in flavonoids precursors called catechins, which is reputed to be 20 times more powerful than vitamin C with respect to its antioxidant properties.
Fruits, vegetables, whole grains, seeds, nuts, beans, legumes, celery, black and green tea, raw cherries, raw parsley, oranges, lemon juice, grapefruit juice, raw blueberries, unsweetened dry cocoa powder are all rich sources of antioxidants.
Epidemiological studies have indicated that the high concentration of phytochemicals may help in stabilizing the free radicals thereby decreasing the risk of cancer. It is also reported that tea could play an important role in changing the genes involved in the process of causing cancer.
An interesting study reveals that even though the cigarette consumption rate in Japan is much higher than in the United States, the lung cancer rate is much lower in Japan. However, a lot more scientific evidence is needed to conclusively determine the extent to which green tea can actually help preventing cancer.
Green tea is believed to aid in weight loss in the following manner:
- Green tea is believed to rev up metabolism- A study reported on in the American Journal of Clinical Nutrition, found that green tea extract consumption resulted in a significant increase in energy. This is probably due to the high concentrations of catechin polyphenols which help increase the rate at which the body burns calories.
- Green tea is thought to inhibit fat absorption and helps glucose regulation – Experts suggest that the catechins in green tea help to inhibit the movement of glucose into fat cells.
- Green tea may help reduce appetite
Several studies have provided evidence that polyphenols and flavonoids have a beneficial effect on two long established heart disease risk factors: high blood cholesterol and high blood pressure (hypertension). Chemical studies revealed that the average blood cholesterol level and systolic blood pressure decreased with increased amount of tea consumption. According to Jim Zhao, Ph.D., chief science officer at Nashville, theaflavins lower LDL (bad) cholesterol by 17 percent in a placebo-controlled, double blind human clinical trial.
Source: Tata tea