Green tea is said to have numerous health-promoting effects due to its high content of important vital substances (micronutrients). It grows in the high mountains of China and is considered a medicinal and stimulant.
Production
For the production of green tea, the tea plant “Thea sinensis” is preferred, as it is a small-leaved, delicate and resistant original plant. The freshly picked tea leaves are either subjected to a two- to three-minute steam treatment at 87 °C, or they are roasted and then air-dried and rolled to make the tea leaf supple for further processing and clear the way for the ingredients to find their way into the cup. Through this gentle method, the valuable vital substances (micronutrients) as well as the natural leaf pigment chlorophyll are largely preserved and harmful microorganisms are destroyed [1.2. ].In the production of black tea, on the other hand, many ingredients that have a beneficial effect on humans are altered or destroyed. In contrast to green tea, black tea is fermented, whereby a reaction with oxygen (oxidation reaction) occurs, which triggers the process of fermentation of the plant sap. As a result, the majority of essential vital substances (micronutrients) such as vitamins, minerals, trace elements and secondary plant compounds are lost. Furthermore, the fermentation or withering process leaves behind many polyphenolic substances which, in high concentrations, can have a damaging effect on the body. Thus, black tea is only a stimulant and is not a wholesome, health-promoting food like green tea.
Ingredients of green tea
Caffeine
The ingredients and effect of green tea are influenced by picking the leaves at different stages of growth and also depend on the cultivation, harvesting, plant as well as processing. Tea leaves contain the alkaloid caffeine (trimethylxanthine), which occurs in tea as teein. The caffeine content varies greatly, as younger, smaller leaves that come from a bush in the shade have up to 50% more caffeine than older, larger leaves or leaf stalks from bushes that receive a lot of sun. A glass of green tea (150 ml) contains on average about 40 mg less caffeine than a cup of coffee, or half as much caffeine as a cup of coffee (50-150 mg caffeine). The following is an overview of the caffeine content of various stimulants:
| Luxury food | Caffeine content [mg] |
| Coffee (150 ml) | 50-150 |
| Espresso (50 ml) | 50-150 |
| Black tea (150 ml) | 30-60 |
| Green tea (150 ml) | 40-70 |
| Cola drink (330 ml) | up to 60 |
| Energy drink (250 ml) | 80 |
| Milk chocolate (100 g) | 20 |
| Semi-sweet chocolate (100 g) | 75 |
Teein from tea exhibits better tolerance than caffeine from coffee. The reason is that although the caffeine is chemically the same compound, it is bound differently. Teein from green tea is bonded with the poorly water-soluble tea tannin, which leads to delayed absorption into the bloodstream and thus has a slower effect on the cerebral cortex. In this way, it can increase mental performance for a longer period of time – about two to three hours. In contrast, the caffeine in coffee is bound to potassium. This bond is immediately broken by the hydrochloric acid in the stomach, which allows the caffeine to enter the bloodstream just a few minutes after ingestion, where it has its stimulating effect all at once. However, the increase in brain power only lasts for a short time – about half an hour – because the caffeine is quickly broken down again. The ingredients of green tea also include the alkaloids theophylline and theobromine. As caffeine-like substances, they have a vasodilatory and blood pressure-lowering effect. As with caffeine, they increase cardiac output by stimulating cardiac activity and facilitating respiration [1.2]. The half-life of caffeine is reported to be four to six hours on average. A daily consumption of 400 mg of caffeine is classified by the EFSA (European Food Safety Authority) as harmless to health for adults.The upper limit for pregnant and nursing women is 200 mg of caffeine per day. For children and adolescents, an intake of 3 mg caffeine per kg body weight/day is considered safe. In this age group, caffeine is mainly ingested through the consumption of energy drinks.
Tannins
The tannins and tannin-like compounds found in green tea, such as catechins (polyphenolic plant metabolites from the flavanols group) and gallic acid derivatives, give the tea its bitter taste. The content of tannins varies from tea leaf to tea leaf. If the leaves grow in a sunny place and in dry conditions, the tannin level is relatively high. Moist as well as shady locations, on the other hand, lower the content of tannins. A high level of tannins in green tea usually results in a low caffeine content, and a low level of tannins usually results in an increased caffeine content.Green tea can contain up to 40% tannins and tannin-like compounds, four times more than black tea.Since tannins bind caffeine substances, these slow down the absorption of the invigorating teein in the intestine, because the caffeine effect of tea does not emanate mainly from the adrenal gland – as is the case with coffee caffeine. The teein bound to the tannins first acts on the autonomic nervous system, on the sympathetic and the parasympathetic nervous system. After stimulation of the autonomic nervous system, coffee caffeine, on the other hand, causes an increased release of the stress hormone adrenaline, which accelerates the pulse and causes metabolic processes to run at full speed for a limited time. As important ingredients of green tea, tannins promote human health by soothing the stomach and intestines as well as the muscles and reducing muscle tension and cramps. In addition to their bactericidal and viricidal effects, they are also antioxidants. Thus, tannins have the ability to prevent harmful oxygen-induced oxidations and protect our body from free radicals, pollutants, heavy metals, destruction of cell membranes, damage to DNA and lipid oxidations. It has been proven that tea tannins, as antioxidants, have an antioxidant effect about twenty times higher than that of vitamin E. Aging processes are slowed down, as tannins can reduce the number of accelerators of aging processes – peroxides. Moreover, they protect especially the heat-sensitive vitamins contained in green tea, such as vitamin C, B1, B6, B12, folic acid, from their destruction during steam treatment. Since the catechins of green tea prevent the action of bacterial toxins, they inhibit inflammation. Green tea tannins lower cholesterol levels by limiting the buildup of so-called bad cholesterol – LDL and VLDL cholesterol. This keeps the LDL cholesterol concentration in the blood relatively low and prevents it from being deposited in high amounts in the tissues and vessels. Consequently, vascular diseases as well as atherosclerosis (arteriosclerosis, hardening of the arteries) can be prevented by drinking green tea.The health-promoting effect of tannins also includes the prevention of high blood pressure. Catechins inhibit the action of a certain enzyme – renin-angiotensin 1 – which is responsible for the formation of the substance angiotensin 2. This substance acts directly on the arterioles, causing blood pressure to rise. By inhibiting renin-angiotensin 1, catechins suppress the production of the blood pressure-increasing substance angiotensin and prevent blood pressure from rising.In addition to catechins, the high-molecular-weight carbohydrates – polysaccharides – contained in green tea also help to reduce blood sugar levels. The tannin in tea leaves inhibits the deposition of the radioactive strontium 90 in bones by causing tannin to form a chemical bond with the divalent metal. The radioactive isotope is subsequently excreted in combination with tannin. Regular drinking of green tea can reduce the absorption of strontium 90 into the body by 20-30%. So-called epigallocatechins – EGCG – belong to the group of catechins, which belongs to the subgroup of polyphenols. These substances have anticancer effects. Epigallocatechins inhibit the two phases of cancer development by preventing body cells from being damaged and their DNA from being altered.Consequently, they reduce the risk of formation and/or activation as well as proliferation of daughter tumors (metastasis) of a cancerous tumor. In particular, epigallocatechins counteract the development of lung cancer. The biochemicals become active directly on the alveoli of the lungs both via the bloodstream and via inhalation of tea vapor. In addition, epigallocatechins deprive tumors of the oxygen they need to grow, as well as vital substances (micronutrients) they require. As a result, regular drinking of green tea greatly reduces the risk of stomach, esophageal, and liver cancer in particular.
Secondary plant compounds – bioflavonoids, saponins and carotenoids
Secondary plant compounds such as flavonoids and saponins are also among the antioxidant ingredients in green tea. Bioflavonoids are polyphenols that, on the one hand, give plants their red, purple, or even brown color and, on the other hand, have strong antioxidant, antimicrobial, antiviral, anti-inflammatory, and immunomodulatory effects [3.1. ].A high flavonoid intake strengthens the immune system and prevents heart attacks by reducing the risk of mortality from cardiovascular disease by circa 33% [3.1. ].Flavonoids have a positive effect on vital substance status. They increase the effect of vitamin C as well as coenzyme Q10 and also delay the consumption of vitamin E. In conjunction with vitamin C and zinc, flavonoids strengthen the structural strength of collagen fibers and thus contribute to the formation of collagenous connective tissue [3.1. ].Flavonoids have anticarcinogenic effects. They can inhibit precancerous lesions as well as metastases (daughter tumors) by blocking enzymes responsible for cancer development and promoting cancer-defending enzymes in metabolism. Since flavonoids have structural similarities to nucleotides, they are able to block binding sites for activated cancer-causing factors and thus inhibit the binding of the harmful substances to the genetic material. In this way, carcinogenic substances and other free radicals are intercepted before they can damage our genetic material (DNA). In addition, these secondary plant compounds can prevent the growth of DNA-damaged cells, especially in breast and colon cancer [3.1. ].Studies on gastric cancer indicate that flavonoids inhibit the growth of gastric cancer cells. As a lot of green tea is traditionally drunk especially in the regions of China and Japan, both men and women there showed a fivefold lower mortality rate from gastric cancer than the average population. A high intake of flavonoids in the form of green tea results in a lower risk of stomach, colon and breast cancer [3.1. ].With increasing tea consumption, the prophylactic effect against caries also increases, as bioflavonoids protect the teeth against caries. Furthermore, they not only inhibit blood clotting, but also counteract coronary heart disease and arteriosclerosis. By combining with harmful alkaloids, flavonoids can reduce the effects of nicotine and tar oil [3.1]. Saponins also contribute to cancer prevention. They bind bile acid in the intestine and are able to reduce the formation of bile acids, which are among the main triggers of intestinal tumors. Consequently, they reduce the risk of colon cancer. In addition, saponins are able to inhibit the growth of various cancer cells [3.1]. They have the ability to bind cholesterol insolubly in the intestine – saponin-cholesterol complex – and thus reduce the absorption of cholesterol. The cholesterol level is lowered: By binding bile acid, more of it can be excreted in the stool. The body’s own cholesterol is then used for the synthesis of bile acid, which also lowers the cholesterol level in the blood.The saponins contained in green tea have an immunomodulatory effect. This effect leads to increased formation of antibodies, which can then fight off antigens in large numbers. The immune system is thus strengthened. In addition, saponins are responsible for increased activity of the immune cells of the spleen, which stimulates the immune system. In addition to these health-promoting properties, these secondary plant compounds are also believed to have antibacterial, antiviral, and anti-inflammatory effects [3.1. ].As a result of research, flavonoids and saponins can help fight HIV infection. They have the ability to inhibit the enzyme reverse transcriptase, which the HIV pathogen needs for its reproduction.The secondary plant compounds carotenoids – beta-carotene, lutein, violaxanthin -, coumarins, chlorophyll and phenolic acids have similar effects to flavonoids and saponins. These protect the body from harmful pollutants and free radicals and thus have antioxidant, antimicrobial, anti-inflammatory as well as anticarcinogenic effects.Carotenoids also have a provitamin A function and are thus involved in important processes in the body, such as the visual process and embryonic development. They stimulate immune cells, can reduce cholesterol levels by 14% and show positive effects in pigment disorders.Together with phenolic acids, they exhibit carcinogenic effects against esophageal, gastric, skin and lung cancer as defense and protective substances. Carotenoids also possess protective effects against prostate, breast, cervical, and colon cancers [3.1. ].The cancer-preventive chlorophyll contained in green tea is important for the body’s oxygen supply and promotes the formation of erythrocytes (red blood cells).
Essential oils
Green tea contains 75 different essential oils. If these act on the body, they gently stimulate the human organism and stimulate sensory perception
Vital substances (micronutrients) – vitamins, minerals, trace elements and amino acids
Green tea further provides a large number of valuable vitamins, minerals and trace elements. Each vital substance (micronutrient) for itself has specific effects on the body, which keep people healthy and prevent diseases. A large part of these substances strengthens in particular the mental performance as well as the health of heart, circulation, digestion, immune system, skin, hair and bone structure. The highest content of vital substances (micronutrients) have especially young, light tea leaves and leaf buds in the youngest growth stage, which are picked in April – Maojiang – as well as May – Quingming. [1.2. ].Vital substances (micronutrients) of green tea – effects on the body.
| Vital substances | Effects on the body |
| Vitamin B1 |
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| Vitamin B2 |
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| Vitamin B3 – Niacin |
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| Vitamin B5 – pantothenic acid[1.2.] |
Essential for
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| Vitamin B12 |
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| Vitamin C |
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| Vitamin E |
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| Vitamin K |
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| Vitamin A |
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| Beta-carotene |
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| Calcium |
Calcium-dependent functions include:
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| Magnesium |
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| Potassium | Necessary for
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| Copper | Important component of enzymes with functions like.
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| Zinc | Is involved in many enzymatic reactions and thus supports
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| Fluorine |
Fluorine is needed for the following reactions:
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| Manganese | Serves to activate enzymes or isa component of them and is thus involved in:
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In addition to vitamins, minerals and trace elements, green tea contains 25 amino acids, which can account for up to 4% of its ingredients. These include theanine, characteristic of the tea bush, aspartic acid and glutamic acid. They support physical as well as mental health through their antioxidant effects. These amino acids calm the nervous system, provide abundant energy to the intestinal walls and white blood cells, and balance blood sugar levels
Quality and varieties
There are many factors that are essential to the quality of green tea:
- Growing location, altitude of the growing area.
- Soil characteristics of the growing area
- Tea plant material
- Harvest time
- Quality of the picking
- Type of leaf processing after picking
Gentle and carefully oriented hand picking of young, uninjured leaves, ensures high quality tea. Only under such conditions can ensure a high health as well as taste value of green tea. The higher the degree of injury of the tea leaves during picking, the more the quality decreases and with it the health-promoting as well as taste value of the tea.In contrast to the carefully hand-picked wild and semi-wild grown green tea, nowadays several machine-made and processed green tea products as well as unrecognizable marketed bagged tea varieties are offered at very low prices. However, with the price, the quality of the green tea also decreases, since the processing effort of machine-made products is nowhere near as high and gentle as that of hand-picked green tea.Due to the high-quality taste and content of vital substances (micronutrients), should be given priority to wild and semi-wild grown green tea, despite the higher price.People who regularly drink high-quality green tea, in addition to the full preservation of their health and increased performance, are rewarded with more vitality and enjoyment of life [2.1. ].Some varieties of green tea from China and Taiwan, Japan, as well as India.
| Name | Origin | Taste | Special features |
| Wokou | ChineseProvince Wokou | Sweet-fresh,fragrant-fine-tart |
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| Jasmine Tea | From the mountainsSouth China | Varies according to the variety |
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| Lu Shan Wu | From the mountains of the southern Chinese province of Kwangsi | Fresh |
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| Lung Ching | South China | Soft, light sweet,extended fresh as well as earthy aroma. |
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| White tea | South China province Fujian | Spicy and slightly bitter |
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| Gunpowder | Taiwan, China | Clear, fresh-tart |
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| Tian Mu QuingDing-Hua Cha | Chinese provinceZhejiangleaves grow inwildmountainlandscapeamidstmanywaterfalls,mountain streamsand lakes. | Fine,invigoratingandorchid-scented |
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| Yun ShanDongting Hu | Chinese provinceHunanNature reserve ofbamboo jungles,rivers and lakesGrows onrocky slopes. | Fine, fresh tasting, sweet tangy and stimulating in the finish. |
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| Oolong | Taiwan, China | Strong, malty |
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| Gyokuro | Kyoto, Japan | Strong with a touch of sweetness |
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| Matcha | Japan, grows in the shade of deciduous trees | fineherb |
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| Sencha | Mainly Japan -Shizuoka, at the foot of Fujijama -also Taiwan, China. | Japanese is fragrant, fresh and light – Chinese is reminiscent of hay. |
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| Green Assam | Assam – Plateau of India | Fresh, fine tart |
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| GreenDarjeeling | Darjeeling -south slopes of theHimalayas, India | Fruity fresh |
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Preparation
In order to absorb the valuable ingredients of green tea in sufficient quantities, it is important to drink at least 3-4 cups daily in high quality as well as properly brewed. Only 8 to 10 grams of tea leaves per liter of water should be used. The water must be boiled and then cooled to about 70-80 °C to preserve the precious active ingredients. The water is poured into a preheated container and poured over the tea leaves, where they should have the opportunity to float loosely and unfold freely. Thus, the leaves give off a better aroma.The total brewing time should be a maximum of 2-4 minutes, as the stimulating effect and concentration of health-promoting ingredients are greatest then. After a short brewing time – up to 4 minutes – relatively few tannins are dissolved, which allows the caffeine to act and the green tea has a stimulating effect on the body. If the green tea is steeped for more than 5 minutes or if too many tea leaves are used, this leads to an excessive release of tannins. However, the tea then loses its delicate, fragrant as well as mildly grassy aroma and acquires a bitter-tart taste. If the tea is drunk with a high amount of tea tannins, it has a rather calming effect on the mind. The reason for this is that the tannins can bind or block the caffeine contained in green tea in the body and thus the invigorating, stimulating effect of the caffeine is absent.It is important that the water in which the tea leaves brew is not warmer or colder than 70 to 80 °C. If it has a lower temperature, the tea is drunk at a lower temperature. If the water temperature is lower, the active ingredients will not dissolve sufficiently and the tea will taste bland. If the water temperature is higher than 70 to 80 °C, essential heat-sensitive vitamins such as vitamin C, B1, B6, B12 and folic acid could be destroyed.After the infusion time is finished, the tea is put into a pot, and the tea leaves are collected with the help of a strainer. Since the green tea is poured off due to the straining of its leaves, it is not an “infusion” but a “pouring”. Only the first infusion should be drunk, as a second infusion using the same leaves will result in an increased release of tannins. A high concentration of tannins in green tea can cause constipation
Refining green tea
Green tea can be additionally refined with lemon juice or even natural honey – with the juice of half a lemon or a teaspoon of natural honey per cup, respectively. However, real green tea drinkers will not love something like this. Milk and cream should not be added to green tea, as both products bind the tea tannins. As a result, the health-promoting effect of the tannins is lost. If green tea is drunk with milk or cream, it no longer has an anti-inflammatory and antibacterial effect, nor does it protect the body from damaging free radicals, nor does it have a preventive effect against breast, stomach, esophageal, liver, lung, prostate, cervical, skin, and colon cancer
Green tea storage
Green tea leaves should be stored in specially coated green tea caddies or in glass, ceramic, plastic, or porcelain containers in a cool, dark place. Common metal tea caddies run the risk of altering the taste of green tea and destroying the delicate vitamin C.
Effects on the body
A variety of preventive and strengthening effects emanate from green tea due to its valuable ingredients.Green tea – effects on the mind
- Makes mentally agile by facilitating thought combinations, stimulating imagination, and combating fatigue and drowsiness [1.2].
- Invigorates the mind when exhausted and perks up, increases attention and alertness without making nervous, supports clear thinking.
- Improves judgment and decision-making, sharpens the eye for differences
- Increases concentration as well as performance
- Calms the nerves when stressed and irritable, when depressed, it cheers up the mind
- People who drink a lot of green tea seem more calm, are more patient and act less rashly [1.2].
- Increases the sense of well-being
- Promotes blood circulation
- Stimulates the respiratory process and favors the absorption of oxygen
- Accelerates the metabolism
- Strengthens the resistance of the body and drives recovery
- Promotes detoxification of the liver and the organism, specifically the breakdown of alcohol, of fats and of waste products.
- Stimulates digestion
- Supports the flow of urine, cleanses the urine
- Strengthens the muscles
- Improves vision
- Cleanses the skin
- Relieves discomfort in the limbs and joints
- Slimming
- Detoxifies the body – six times stronger than black tea
- Prolongs life expectancy
The valuable ingredients of green tea have a positive effect not only on the mental state, but also on the external appearance. It supports the natural beauty of the person by intercepting the numerous environmental pollutants through it. Such harmful substances affect our organism and lead to increased formation of free radicals in the body – oxidative stress. Free radicals are extremely aggressive, multiply in the form of chain reactions – snatching an electron from the attacked molecule and turning it into a radical – and attack, damage or destroy biological structures such as amino acids, cell membranes and the hereditary substance. They also contribute to the acceleration of skin aging. Green tea can prevent the damaging effects of free radicals, as its health-promoting substances detoxify the free radicals. Thus, it delays the formation of wrinkles as well as the aging of the skin. Since green tea calms the nerves, it helps to better cope with the effects of stress. People who regularly drink green tea radiate greater calm from within, appear more relaxed, revitalized, active as well as healthier. Green tea drinkers are in harmony with themselves and their environment [1.2. ].Green tea supports the loss of body fat, because the tannins it contains create a slight feeling of satiety. Accordingly, dieters benefit from green tea as a calorie brake as well as a safe source of vital substances due to its high content of vitamins, minerals, trace elements and valuable bioactive substances. Green tea is suitable in consequence also well for chamfering cures. In addition to the daily intake of at least 2 liters of calorie-free beverages, about 0.75 liters of green tea should be consumed. It soothes the stomach and intestines and detoxifies the body by neutralizing acid metabolites. Green tea has the ability to support the treatment of diseases or certain conditions. A meta-analysis showed that long-term consumption, that is, ≥ 12 weeks, of green and black tea resulted in a significant reduction in systolic as well as diastolic blood pressure. Another meta-analysis showed that individuals who drank more than one cup of green tea daily, compared with those who did not, had a lower risk of cardiovascular disease (CVD), intracranial hemorrhage (hemorrhage within the skull; parenchymal, subarachnoid, sub- and epidural, and supra- and infratentorial hemorrhage)/intracerebral hemorrhage (ICB; brain hemorrhage), and cerebral infarction (apoplexy/stroke). From a daily intake of two to three cups, the risk of myocardial infarction (heart attack), hyperlipidemia (dyslipidemia), as well as apoplexy (stroke) decreased compared to the group that drank more than one cup of green tea per day. When the daily drinking amount was increased to four cups, the risk for myocardial infarction and hyperlipidemia was again lower compared to those who drank more than one cup per day.Starting at a daily drinking amount of more than 10 cups of green tea, LDL cholesterol levels decreased in participants compared to the group who drank more than three cups per day. Green tea for cardiovascular disease
- Prevents hardening of the arteries (atherosclerosis, arteriosclerosis)
- Reduces the risk of myocardial infarction (heart attack), intracranial hemorrhage (brain hemorrhage), apoplexy (stroke).
- Improves the condition after a myocardial infarction as well as apoplexy
- Prevents high blood pressure (hypertension)
- Lowers both systolic and diastolic blood pressure levels.
- Lowers elevated LDL cholesterol levels
- Prevents angina pectoris (“chest tightness”; sudden pain in the heart area)
- Prevents heart failure (heart failure), heart disease and narrowing of the coronary arteries – coronary heart disease (CHD).
- Prevents blood vessel occlusion by a blood clot (thrombosis), which can lead to cardiac overload as well as cardiac arrest.
Green tea strengthens the immune system and performs well in:
- Diseases of the common cold
- Headache
- Intestinal infections
- Fungal diseases of the intestine
- Athlete’s foot – foot bath with green tea
Green tea prevents metabolic diseases such as:
- Diabetes mellitus
- Hyperlipidemia (elevated blood lipid levels)
- Gout
Green tea for cancer
- Prevents breast, stomach, esophageal, liver, lung, prostate, cervical, skin and colon cancers
Green tea supports the treatment of digestive disorders and thus prevents:
- Belching
- Gastroesophageal reflux disease (synonyms: GERD, gastroesophageal reflux disease; gastroesophageal reflux disease (GERD); gastroesophageal reflux disease (reflux disease); gastroesophageal reflux; reflux esophagitis; reflux disease; Reflux esophagitis; peptic esophagitis) – inflammatory disease of the esophagus (esophagitis) caused by the pathological reflux (reflux) of acid gastric juice and other gastric contents.
- Stomach acidity as well as heartburn
- Inflammation of the gastric mucosa (gastritis)
- Diarrheal diseases before
Green tea counteracts dental diseases as:
- Caries
- Periodontitis (gum recession)
- Gingivitis (inflammation of the gums)
Furthermore, green tea prevents osteoporosis or supports the treatment of this bone disease. Green tea also counteracts nephrolithiasis (kidney stones) and kidney problems, and is able to alleviate urolithiasis (urinary calculus disease) Excessive green tea consumption leads to deficiency of [3.1-2] due to caffeine:
- Vitamin C
- Vitamin B6
- Calcium
- Iron
