Healthy effects of green tea

 

Introduction

Green tea infusion has long been recognized as a healing drink. Traditional Chinese medicine claims that green tea improves blood flow, relieves joint pain, strengthens immunity and detoxifies the body. Modern medical research proves the healing properties of tea in relation to developing cancer, neurodegenerative diseases, atherosclerosis and obesity. Green tea is rich in polyphenolic compounds from the group of flavanols, flavonoids, proanthocyanidins and phenolic acids. Green tea is mainly grown in China, Japan and Taiwan, and to a lesser extent also in India.

               

Chemical composition and health effects
               
The chemistry of green tea is very similar to that of freshly plucked leaves, except for a few enzymatic changes that occur rapidly after the leaves are plucked. Freshly picked leaves contain 30-40% polyphenols, 17% protein, 4% caffeine and 27% fiber, and small amounts of β-carotene, vitamins B, D and ascorbic acid. Green tea contains vitamin C which is destroyed by the fermentation process. The polyphenols in green tea are more known as flavonoids or catechins, represent

30-40% of the soluble substances of green tea leaves. Flavonoids are found in all parts of plants, especially in photosynthetic cells, and are an integral part of human and animal diets. The high chemical activity of flavonoids is related to the binding of polymers and heavy metal ions and the ability to catalyze the transport of electrons and scavenge free radicals. Tea contains 200 to 300 mg of flavonoids in 1 cup.

Catechin is a type of tannin that is specific to green tea. Tannins are polyphenols, have an astringent flavor, and can be found in several thousand types in plants. As many as 2,000 of them are known to form a flavonoid structure and are called flavonoids. Catechin is one of them. There are 4 main catechins in green tea that differ in their degree of antioxidant effectiveness. They are: epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC). EGCG is the most powerful catechin. EGCG acts as an antioxidant 25 times more powerful than vitamin E and 100 times stronger than vitamin C. A cup of green tea can provide 10–40 mg of polyphenols and has a stronger antioxidant effect than a serving of broccoli, spinach, carrots or strawberries. The high antioxidant activity of tea has a benefit by protecting against oxidative damage caused by free radicals.

Species	polyphenols (in g/100 g  dry weight of leaves)					Tannin	Caffeine
	catechin	EC	EGC	ECG	EGCG
C. sinensis var. sinensis	0,07	1,13	2,38	1,35	8,59	1,21	2,78
C. sinensis var. assamica	0,02	1,44	0,035	3,35	12,10	1,43	2,44

Catechins react with toxins formed by harmful bacteria (mainly those belonging to the protein family) and harmful metals such as lead, mercury, chromium, and cadmium, breaking them down.

 

The health benefits of consuming catechins are as follows:

- they eliminate free radicals, preventing the growth of cancer cells by blocking the growth of substances that cause cancer. It also stops the aging process.

- combine with cholesterol, absorb it and block it, thus lowering its level in the blood. They also prevent the formation of bad cholesterol caused by oxidation, which prevents blood vessels from constricting due to the accumulation of this cholesterol,

- prevent arteriosclerosis, thrombosis, heart attacks and brain injuries,

- they effectively reduce high blood pressure,

- they block the action of enzymes that absorb and absorb sugar, preventing diabetes,

- they fight bacteria and viruses and prevent flu, food poisoning and caries,

- improve intestinal peristalsis, stopping the proliferation of harmful bacteria and increasing the number of bacteria needed,

- combine with various substances (contained, for example, in fish, meat, etc.), preventing unpleasant odors,

- they change harmful ultraviolet radiation into harmless light in plants, thus protecting them.

 

Tea polyphenols act as antioxidants to eliminate reactive oxygen and nitrogen (nitrosyl) radicals as well as chelators of active metal ions in the redox system. Both radicals and active metal ions are very toxic because they destroy lipids, proteins and nucleic acids.

As antioxidants that reduce the formation of free radicals in the body, polyphenols can also indirectly influence the inhibition of pro-oxidative enzymes such as induction nitric oxide synthetase, lipoxygenase, cyclooxygenase and xanthine oxidase. Bacterial endotoxins as well as pro-inflammatory cytokines stimulate macrophage expression of the inductive isoform of nitric oxide synthetase, resulting in the formation of large amounts of active nitric oxide. Nitric oxide reacts spontaneously with superoxide to form peroxynitrite and other oxidants which destroy DNA and proteins. Both green and black tea, as well as individual catechins and theaflavins, have the ability to inhibit both the expression and activity of iNOS in macrophages. Green tea catechins and theaflavins in black tea inhibit iNOS by blocking the activity of the nuclear factor-kB.

 

Cellular antioxidants not only eliminate reactive radicals directly, they also induce the expression of genes encoding the synthesis of defense proteins, such as glutathione peroxidase, gammaglutamylcysteine ​​synthetase, NAD (P) H: quinone reductase, or heme oxygenase-1, among others. EGCG, the quantitatively dominant catechin in green tea, has been shown to inhibit DNA oxidative damage and cytotoxicity caused by tobacco nitrosamine, which causes lung cancer. A similar preventive effect of EGCG was observed with respect to the photocarcinogenic effect of UV radiation on the skin. The anti-cancer effect of EGCG was correlated with a reduction in the production of free radicals, reduced lipid peroxidation and maintenance of intracellular glutathione activity. Moreover, EGCG influences the restoration of detoxification enzymes such as glutathione S-transferase, glutathione peroxidase, superoxide dismutase, and catalase. Although these observations confirm the effect of EGCG on stimulating the antioxidant defense mechanisms of the cell, limiting the possibility of carcinogenesis, they reveal only one of the mechanisms of possible action of tea catechins on the body.

Drink it the best tea for health!