Green tea is minimally processed and thus contains the most polyphenols, especially catechin called 3-epigallocatechin gallate (EGCG), which is responsible for most of the health benefits associated with drinking green tea.Green tea is produced by quickly evaporating freshly harvested leaves, which makes them soft and flexible and prevents fermentation or color changes.After evaporation, the leaves are rolled, then unfolded and dried with hot air or fried in a wok until they become brittle.The greenish-yellow tea obtained in this way has a slightly tart flavor reminiscent of the taste of fresh leaves.
During the production of black tea, the leaves are first laid out on stands and dried with compressed air, which removes about one third of their moisture and makes them soft and flexible.Then they are rolled up to break their cell walls, releasing the juices necessary for fermentation.Once again they are decomposed and stored under high humidity conditions to maintain proper fermentation, which leaves the leaves dark copper color and gain a characteristic aftertaste of black tea.Finally, the leaves are dried, resulting in a black and brown tea, whose immersion in hot water makes it possible to obtain a reddish-brown infusion with a more pronounced taste than in the case of green tea or oolong tea.
Green tea is particularly rich in beneficial flavonoids (which constitute 30% of the dry weight of the leaf), including catechins and their derivatives.The most abundant catechin is gallusan-3-epigallocatechin (EGCG), which plays a key role in the antitumor and antioxidant effects of green tea.Catechins are just as useful as more well-known antioxidants, such as vitamin E and C, are also a powerful health promoting agent.
Most studies showing the health benefits of drinking green tea were based on the amount of green tea usually consumed in Asian countries, or about 3 cups a day (which means a dose of 240-320 mg of polyphenols).Only one cup of green tea provides20-35 mg EGCG, which is characterized by the highest antioxidant activity of all green tea catechins.
Fans of green tea have greater resistance to many diseases, ranging from simple bacterial or viral infections, ending with chronic degenerative diseases, including cardiovascular diseases, cancers, strokes, periodontal disease and osteoporosis.
Protection against coronary disease
In Japanese studies, green tea consumption may be an independent basis for predicting the risk of coronary artery disease.In one study, people drinking 5 or more cups of green tea daily were 16% less likely to have coronary heart disease.This relationship was so significant that scientists came to the following conclusion. The more green tea patients take, the less likely they are to develop coronary heart disease.
The greater amount of free radicals in the arteries is a key element in many forms of cardiovascular disease.Recent research shows that catechins contained in green tea inhibit the activity of enzymes involved in the production of free radicals in the endothelium of the lining of the blood vessels.The endothelium of the artery is one cell thick and serves as an interface between the blood and the arterial wall, where platelets accumulate.By protecting the endothelium against free radicals, green tea catechins help to prevent the development of cardiovascular disease.
Prevention of atherosclerosis
Green tea effectively reduces the risk of atherosclerosis, reducing LDL cholesterol, triglycerides, lipid peroxides (free radicals that damage LDL cholesterol and other lipids and fats) and fibrinogen (blood proteins involved in the formation of blood clots), while improving the LDL cholesterol ratio (bad) to HDL (good).
It thins the blood and helps prevent the formation of blood clots
The catechins contained in green tea enhance blood clotting and prevent the formation of blood clots, preventing the formation of pro-inflammatory compounds derived from omega-6 fatty acids found in meat and polyunsaturated vegetable oils, such as corn, saffron and soybean oil.These pro-inflammatory compounds, namely arachidonic acid, which produces inflammatory cytokines, thromboxane A2 and prostaglandins D2, contribute to the clumping of platelets together.
It protects the heart of patients with acute cardiovascular failure
The basic catechin of green tea, EGCG (3-epigallocatechin gallate) is so powerful that it can help prevent myocardial cell death when ischemia / reperfusion.Ischemia is a medical term that determines the limitation of blood supply, and thus oxygen and nutrients.After the restoration of circulation, oxidative damage occurs, which is referred to as reperfusion injury.
EGCG prevents damage to the myocardium by blocking compounds that activate inflammation (including NF-kappa-B and STAT-1), which play a key role in the formation of oxidative stress, which kills cardiac cells during reperfusion injury.Researchers believe that EGCG can be used to reduce complaints in patients with acute coronary heart disease.
It lowers blood pressure and prevents arterial hypertension
Research published in July 2004 in the edition of Archives of Internal Medicine found that among people who consumed tea regularly, for at least a year, the risk of developing hypertension was 46% lower among those who drank ½ to 2½ cups per day and 65% lower among people consuming more than 2½ cups a day.
In another study, one of the breeding rats not only had high blood pressure, but was also susceptible to heart attacks.After administration of green tea, it had significantly lower systolic and diastolic blood pressure compared to the control group that received pure water.Animals in this study, which was published in January 2004 in the Journal of Nutrition, consumed the equivalent of a human 1 liter (slightly over 4 glasses) of green tea per day.
It helps prevent the development of atherosclerosis and cancer
Both atherosclerosis and cancer, cell growth and proliferation is key to the disease process.In atherosclerosis, plaques accumulate in the walls of the arteries, which are getting thicker and less elastic, hindering the flow of blood.In cancer, standard brakes in cells do not work, and they themselves multiply in an uncontrolled way.Green tea can help prevent unnatural cell proliferation.
Catechins, in addition to other main active ingredients in green tea leaves, close the main relay station, through which messages are sent to promote the growth and development of both atherosclerosis and cancer.These relay stations, called tyrosine kinase receptors, are necessary for transmitting messages from platelet growth factors, insulin-like growth factors, epidermal growth factors, fibroblast growth factors and vascular endothelial growth factor.The result is the prevention or cessation of disease processes that depend on excessive cell growth.
EGCG is used for specific prophylaxis of prostate cancer.A study published in December 2004 in the International Journal of Cancer proves that EGCG significantly reduces the dose-dependent production of specific prostate antigen (PSA), which is a marker of prostate cancer risk.EGCG not only reduces the level of PSA, but also limits any activity of PSA that has been studied and can cause prostate cancer.