Harmful properties of green tea. Is it healthy to drink green tea? And why it is considered harmful. How to make green tea properly
Is it useful green tea? And if yes, then to whom and how much?
This drink has been used since ancient times to relieve depression and headaches, and modern people also noted its ability to burn fat, lower blood pressure and the level of bad LDL cholesterol in the blood. Today the blog "Forest Fairy" will consider in detail beneficial features green tea for the human body, the correct methods of brewing it and individual cases in which its use can harm your health.
Before you find out what the benefits of green tea really are and what are the contraindications for it, check out these interesting facts:
The benefits and harms of green tea for the body. What does this drink contain?
Green tea is a rich source of potassium, vitamin C and some B vitamins, which dissolve well in water and are absorbed by our body. Another important component of green tea is the antioxidant flavonoids, including proanthocyanidins who actively fight against age-related diseases, diseases of the circulatory and digestive systems.
This table and the information below will tell you more about the health benefits of green tea.
| Indicator | Unit rev. | Per 100 g. | 1 cup |
| general information | |||
| Calorie content | Kcal | 1 | 2 |
| Squirrels | G. | 0.22 | 0.54 |
| Fats | G. | 0.00 | 0.00 |
| Carbohydrates | G. | 0.00 | 0.00 |
| Dietary fiber (fiber) | G. | 0.0 | 0.0 |
| Sugars (including glucose and fructose) | G. | 0.00 | 0.00 |
| Minerals and electrolytes | |||
| Iron | mg. | 0.02 | 0.05 |
| Magnesium | mg. | 1 | 2 |
| Potassium | mg. | 8 | 20 |
| Sodium | mg. | 1 | 2 |
| Zinc | mg. | 0.01 | 0.02 |
| Copper | mg. | 0.004 | 0.010 |
| Manganese | mg. | 0.184 | 0.451 |
| Vitamins | |||
| Vitamin C | mg. | 0.3 | 0.7 |
| Thiamin (vitamin B1) | mg. | 0.007 | 0.017 |
| Riboflavin (vitamin B2) | mg. | 0.058 | 0.142 |
| Niacin (vitamin B3 or PP) | mg. | 0.030 | 0.073 |
| Vitamin B6 | mg. | 0.005 | 0.012 |
| Other substances | |||
| Caffeine | mg. | 12 | 29 |
| Antioxidants proanthocyanidins | mg. | 4.2 | 10.4 |
Source of numbers: US National Nutrient Database for standard reference. The numbers characterize ordinary green tea brewed with water and may vary slightly depending on the variety and growing conditions of the product.
Antioxidants in Green Tea and Their Effects on the Body
Green tea has a fairly high content of plant antioxidants - flavonoids and catechins, the most active of which is epigallocatechin gallate or EGCG... It is a very powerful antioxidant that many scientists believe can slow the growth of cancer cells and the aging of the body. Together with other antioxidants in green tea, including proanthocyanidins, it also helps:
- Facilitate digestion and speed up the body's metabolism;
- Lower blood pressure and blood LDL cholesterol levels;
- Freshen breath and eliminate bacteria that cause tooth decay and other diseases of the oral cavity.
Attention: To date, insufficient clinical studies have been conducted to make it possible to use green tea or its extracts with complete confidence in the treatment of cancer and cardiovascular diseases. For example, studies that confirmed the ability of green tea to reduce the risk of developing liver cancer were carried out only among the Chinese and Japanese populations.
Yet current evidence on how green tea acts on different people with their individual characteristics, remain rather limited. Before using it in medicinal purposes be sure to consult with your doctor and follow the recommended dose.
Is the caffeine in green tea good or bad?
A cup of green tea contains on average about 30 mg of caffeine. By comparison, black tea has an average of 55 mg, Red Bull has 75 mg, and regular coffee has 90 mg of caffeine per 250 mg cup. How does this affect a person?
Caffeine is known to have an energizing effect on the brain, energizing and uplifting. However, the antioxidant EGCG and L-theanine in green tea neutralize the effects of caffeine to some extent and make the drink much safer. L-theanine is one of the few amino acids that reduces anxiety, lowers blood pressure, relaxes, improves learning, and boosts immunity. Therefore, you can always drink a cup of green tea in the evening without fear of insomnia.
Note: with the usual method of brewing tea, we get a fairly small amount of L-theanine. To completely release it into a drink, the first infusion of green tea is drained, after which the leaves are boiled at high temperature water up to 127 ° C.
It should also be noted that caffeine dehydrates the body and is considered a good diuretic. There are studies that have shown that the catechins in green tea prevent caffeine from dehydrating the body. However, many people have noticed that after drinking tea they start to run to the toilet more often. Therefore, just listen to your body and do not abuse this drink if it has a similar effect on you.
Finally, we note that many scientists consider the caffeine in green tea safe and even assigned it the GRAS status (definitely safe products and ingredients). In any case, today green tea remains the safest and healthiest of all caffeinated drinks.
Does green tea raise or lower blood pressure?
Due to the caffeine content, the question is often asked: does green tea raise or lower blood pressure? We have already mentioned above that L-theanine neutralizes the effect of caffeine, but the amount of this amino acid in a drink directly depends on the way it is brewed. It also contains catechins, which have a beneficial effect on the heart and blood vessels. What is the effect of green tea in general?
All the experiments carried out gave one result: green tea lowers blood pressure. The cumulative benefit of green tea for hypertensive patients is obvious! A general meta-analysis of studies showed that consistent consumption of green tea for 3-6 months reduced systolic and diastolic blood pressure by about 3 mmHg. Art.
Does green tea really help you lose weight?
No global trials have yet been performed to support the weight loss benefits of green tea. However, there are a number of facts supporting this statement:
- Green tea tends to speed up metabolic processes, which makes the human body burn calories faster without any exercise.
- Green tea is not able to suppress appetite, but it can temporarily increase the body's endurance. The polyphenols in its composition accelerate thermogenesis (the production of heat by our body to maintain the work of all its systems) and contribute to the use of calories for energy.
- The catechins in green tea help regulate blood sugar and prevent obesity by inhibiting the storage of glucose in fat cells.
- The caffeine we talked about above interacts well with polyphenols and also increases the rate of fat burning.
Slowly but surely, green tea helps you lose weight by causing your body to lose fat while maintaining muscle mass.
Potential harm of green tea to the human body
Moderate regular consumption of green tea is generally considered safe, but still has some limitations and contraindications.
So, green tea can be toxic to the liver if the recommended consumption rates are exceeded (10-29 mg of tea per 1 kg of body weight per day). In addition, too high a dose of green tea, which is high in antioxidants, can act as a prooxidant and damage healthy cells in the body.
Heartburn and indigestion are common consequences of overconsumption and / or improper brewing of green tea. This harm can be prevented by brewing the drink in water at a temperature well below its boiling point. Ideal - in the range of 71-82 degrees Celsius.
Also, green tea may be contraindicated in the following cases:
- Iron-deficiency anemia. Consuming green tea can create an iron deficiency in your body, which can be severe in people with anemia. This harmful property of tea can be neutralized by adding lemon to it.
- Allergy. It is extremely rare, but some people still have an allergic reaction to Chinese green tea: swelling of the throat, difficulty breathing, swelling of the lips, tongue and / or face, fever.
- Sensitivity to caffeine. When consumed excessively or hypersensitive to caffeine, green tea can cause anxiety, heart palpitations, irritability, trouble sleeping, etc.
- Pregnancy. Green tea is not recommended to be consumed in large quantities by pregnant women, especially in early dates... Caffeine, tannins and catechins in its composition can lead to birth defects.
- Taking medications. When receiving medical supplies be sure to check with your healthcare professional regarding your green tea consumption.
Of course, the benefits of green tea depend on the amount you consume. Experts recommend drinking 10 to 29 mg of green tea per kg of body weight per day. Thus, for a person weighing 60 kg, the recommended dose is in the range of 600-1740 mg (2 to 6 cups), and for a person weighing 85 kg, in the range of 850-2465 mg (3-9 cups). However, given the existing contraindications and research data, it is better not to bring the amount of tea drunk per day to the upper limit. According to several studies, 6 cups of green tea is too much for normal daily consumption. Side effects of this can include frequent urination (and therefore dehydration), diarrhea, vomiting, dizziness, headaches, and loss of appetite.
Be healthy!
So many good words have been said about him that it is even somehow inconvenient to discuss the benefits and harms of green tea. But many, although they know about him healing abilities, cannot say exactly what they are. Usually it is limited to a couple of properties - "cleans blood vessels", "helps to lose weight." What, then, is the uniqueness of the drink? Let's figure it out!
Green and black tea are not even relatives, but they are essentially the same "character", because the tea leaves for the first and second types are harvested from the same bushes. It's all about processing. Green tea, unlike black tea, does not undergo fermentation. Moisture is simply evaporated from it. Thanks to the gentle production technology, it completely retains in its composition the valuable substances inherent in it by nature.
What are these components that determine the properties of green tea and its benefits and harms? It contains a veritable arsenal of antioxidants. There are as many of them in a cup of emerald drink as in ten glasses of apple juice! About 15-30% of its composition falls on tannins. These are up to 30 types of polyphenolic compounds, including tannin, catechins and others.
The peculiar aroma of green tea is provided by the presence of essential oils, and they largely determine the quality of such a drink. It contains amino acids, among which glutamic acid should be noted - it puts in order the metabolism and restores "shattered" nerves. Green tea contains vegetable proteins, so that it not only gives water, but also feeds.
To explain the benefits of green tea, just look at the list of its medicinal properties.
The healing effect of green tea:
- inhibits aging, prolongs youth, increases lifespan: this effect is associated with a high content of antioxidants;
- reduces the likelihood of contracting cancer: Japanese scientists have conducted studies for 12 years that have confirmed that daily consumption of such a "product" significantly reduces the growth rate of a malignant tumor (but to obtain such a result, you need to drink up to 1.5 liters of tea, which is 19 cups) ;
- enhances immunity;
- removes toxins, carcinogens, neutralizes toxins;
- supports the heart, reduces the risk of heart attack in half;
- helps to destroy excess fat, suppresses appetite, which helps in the fight against excess weight;
- improves metabolism;
- removes "bad" cholesterol;
- stabilizes blood sugar levels;
- increases the strength of blood vessels;
- reduces alcohol cravings;
- activates brain activity;
- protects the liver from the destructive effects of alcohol;
- reduces pressure (by 10-20 units);
- prevents tooth decay and gum inflammation;
- provides sharp eyesight;
- gives vigor, increases efficiency;
- neutralizes the negative influence of waves emitted by the computer monitor.
It is widely believed that green tea is better than regular water at quenching thirst and restoring water loss.
Does the drink harm the kidneys?
What is green tea for the kidneys? Benefit or harm to this vital organ from such a drink? It is a powerful diuretic. If you drink it like water - often and in large quantities, then you can bring yourself to dehydration. This will help to increase the concentration of salts and acids in the kidneys. As a result, stones will appear in them.
It is strongly not recommended to use it in large quantities for those people who suffer from diseases of the urinary system. Urologists advise you to limit yourself to a couple of small cups per day. And after drinking tea, be sure to drink 250 ml of plain water to compensate for the loss of fluid.
That's how he cured! Possible negative consequences
Among drinks for daily use(we are not talking about herbal decoctions) it is difficult to find a more multifunctional "medicine" than green tea. Its benefits and harms to the body are incomparable.
But this does not mean that if you drink it in liters, you can throw out all the medicines from your home first-aid kit and forget the way to the clinic. Green tea requires careful handling. If you drink it without measure, too strong, and even on an empty stomach, you can face very unpleasant side effects.
Adverse reactions that green tea can provoke:
- headache;
- nausea;
- dizziness;
- sleep disorder;
- irritability;
- loose stools;
- tremor of the limbs;
- heartburn;
- feeling of discomfort when urinating;
- convulsions.
To avoid such "surprises", it is enough to adhere to simple rules: drink only high-quality tea, consume no more than 2-3 cups per day, take the last portion at least three hours before bedtime, do not swallow the burning drink (if its temperature is above 60 degrees , then it will increase the risk of stomach cancer).
Important! If you drink liters of green tea, you can "drink up" to problems with the liver, as an overdose of polyphenols will occur.
And I would drink, but health does not order!
If you drink it without taking into account contraindications, then all the benefits of green tea will come to naught. Even such an eminent "doctor" is not shown to everyone.
Diagnoses in which it is better to refuse such a drink:
- urolithiasis: since green tea has a rather pronounced diuretic effect, it can provoke the movement of stones;
- anemia: this drink impairs the absorption of iron in the body;
- an ulcer, serious pathologies of the digestive system: if there are such problems, then you will have to exclude this tea from the menu, because it increases acidity;
- nervous disorders accompanied by overexcitation, insomnia, tachycardia: tea will only aggravate the patient's condition, as it contains caffeine;
- hypotension: from green tea, the pressure will drop even lower, but this will not happen if you cook it in low concentration, but if you pour a spoonful "with a slide" on one cup, then blood pressure can drop to critical levels;
- gout.
Green tea is not suitable for young children either, because their nervous systems are still developing. This means that they don't need to take "stimulants" (even natural ones) at all.
There are different opinions as to whether green tea is allowed for expectant mothers. Its benefits and harms to the body of a pregnant woman have not yet been fully investigated. But gynecologists do not recommend leaning on it in the first trimester, as it makes the uterus in an increased tone, which causes the danger of fetal rejection.
Starting from the fourth month, such a strict ban is lifted, but in order to exclude even the slightest risks for the baby, it is better for a woman "in position" to limit herself to one cup of this "medicine" a day.
Drink, so according to the rules!
How do you use its medicinal properties to get all the benefits of green tea? In order to feel the healing power of the drink of Japanese centenarians on your own health, you need to learn how to properly prepare it.
Top five secrets of green tea preparation:
- for brewing, use a faience (in extreme cases, a ceramic) teapot with a lid;
- take clean (not tap!) water, add 1 small spoonful of tea leaves to 250 ml of liquid;
- pour them into a preheated teapot;
- rinse the tea leaf with cool boiling water (this will reduce the concentration of caffeine), then pour it over hot water(with temperatures from 70 to 85 °);
- do not dilute the tea with water, but instead of sugar, it is better to take honey (add it when the temperature of the drink drops to 50 degrees).
Important! According to connoisseurs of tea traditions, such a drink gives out all its healing properties only from the third brew!
People knew in antiquity that a drink made from green leaves of a tea bush is very useful for health. For many centuries it has been used as a therapeutic and prophylactic natural remedy for many ailments. Knowledge about the benefits of green tea has reached our days.
It is recommended to drink it by traditional medicine experts, nutritionists. You just need to take into account the existing contraindications for use. Today we will conduct a small study with you to find out whether green tea is useful or harmful, how much of a drink you can drink per day without harming your own health. First, let's find out what is good for green tea?
Beneficial features
We note right away that green tea leaves are extremely rich in composition. They contain several hundred names of biological substances and compounds. There are mineral salts, valuable food acids, practically all vitamins known to pharmacists.
The main value of green tea leaves are alkaloids. Although, on the one hand, they can bring undoubted benefits to the body. But if the drink is abused, it can be harmful. For example, a well-known alkaloid - caffeine. This substance gives vigor, fills the body with energy, increases efficiency. And at the same time, in large quantities it can harm the health of the nervous system, heart, blood vessels, increases the fragility of bones.
True, green tea does not contain pure caffeine, but a milder one - theine. It does not have such a negative effect, it is quickly excreted from the body. Unlike caffeine, it does not excite the nervous system, but invigorates, improves tone, and improves performance. However, green tea still not worth overusing.
Quality varieties contain high amounts of catechins. These are flavonoids that have powerful antioxidant effects on the body. Catechins keep our youth, improve skin condition. They protect against damage to the tissue of the heart and blood vessels. They are very necessary for a person, as they reduce the risk of developing diabetes, osteoporosis. These substances improve, activate metabolic processes, contribute to the elimination of fatty deposits.
Tea leaves contain extremely valuable vitamin R. Without it, the normal functioning of the body is simply impossible. It must be said that vitamin P is not just one substance, but a whole complex of the most useful plant bioflavonoids. They neutralize the action of free radicals and help to cope with allergies. They improve the condition of the cardiovascular system, make the capillary walls more elastic.
Other useful properties of green tea should be noted. For example, with regular use of a freshly brewed drink, the quality of vision improves, memory is restored, and Creative skills person. Many people note the ability of the drink to relieve symptoms of depression.
Why is it harmful?
The beneficial properties of the drink are beyond doubt. However, excessive consumption can be harmful. For example, if you drink it in large quantities, often, brew it tightly, this can have the most negative effect on the kidneys, namely, provoke the development of urolithiasis.
Its excessive use is adversely affected by the liver. If you drink strong green tea in liters, the liver accumulates polyphenols. Small amounts of these substances are very beneficial for the body. But when a lot of them accumulate, it causes poisoning.
You also need to know that not everyone can drink the drink from the green leaves of the tea bush, or you should strongly limit its use. For example, you can drink it with caution for people suffering from diseases. of cardio-vascular system, as well as with hypotension. In people with peptic ulcer disease, gastritis, the drink can cause heartburn, stomach pain.
Pregnant women, nursing mothers can drink it, but only very weakly brewed and only during the day. Do not drink it in the evening and then breastfeed your baby. In this case, sleep disturbance may occur in the mother and child. Everyone else also does not need to drink tea at night, especially strongly brewed tea.
It is certainly harmful for gout sufferers, as its use increases uric acid levels.
You need to be more careful for people involved in sports, who drink it instead of water, in between intense workouts. So, this is absolutely impossible to do - you can get serious poisoning. Therefore, it is best to drink plain, non-carbonated water during training.
Of course, all this does not mean that you need to completely abandon the healthy aromatic drink. A small amount will not hurt anyone. You just need to know when to stop, take into account some cooking rules. For example, if you need to cheer up, brew the tea for 2 minutes. If you need, on the contrary, to calm down, brew it for 5 minutes.
The main thing is not to brew it for longer - then it can really lose its beneficial properties. Don't get too carried away with it. 3-4 total small portions enough for a day. Be healthy!
Green tea is a favorite drink of many. It is distinguished by a special way of processing green tea leaves. Its fermentation is minimal, so everything nutrients(vitamins and minerals) remain in this type of tea. There are several varieties of green tea, they differ both in the varieties of tea bushes and in the country of origin. He came to our country from China, but became popular quite recently, when they began to talk about its benefits, there were many articles about green tea. Only, speaking about the benefits, few people think about whether it is harmful
Why is this drink harmful? In fact, drinking green tea can cause some side effects. These are cardiac arrhythmias, blurred thoughts, retarded thinking. These factors can occur with excessive consumption of the drink. A huge amount of the drink, drunk immediately, can cause tremors of the fingers, weakening of the body, and sleep problems.
With exacerbation chronic diseases associated with the gastrointestinal tract, high temperature green tea is categorically contraindicated. Elderly people, as well as pregnant women, are not recommended to get too carried away with green teas. It should be remembered that everything is good in moderation.
In China, tea is never drunk during a meal. It is able to slow down the digestion process. To prevent this from happening, you need to wait a couple of hours after a hearty lunch, and then enjoy fragrant tea.
Drinking too hot tea is not recommended. Because according to a study in America, regular consumption of a hot drink will negatively affect the health of the esophagus and stomach. A large amount of a healthy drink, which contains the substance polyphenol, leads to its accumulation in the body, and this is harmful to internal organs... This amount can lead to liver and kidney problems.
It is very dangerous to drink yesterday's tea. Green tea brewed the day before becomes a harmful mixture filled with microorganisms, losing all its invaluable properties. You need to brew tea only before tea drinking.
It is harmful to use tea bags all the time. They are of no use whatsoever. There is no particular harm either, but why use tea dust and tea waste for brewing? Preference should be given to high-quality teas, the best green tea is large-leaf, grown and produced in China.
Green tea: combination with alcohol
Alcohol (in any form) is very dangerous in itself, but when combined with green tea, it can cause irreparable harm to health. Drinking alcohol along with tea, before or after drinking it, puts a lot of stress on the kidneys, heart, and nervous system. If a person already has problems with these organs, the load becomes deadly.
Some people recommend drinking a cup of tea to combat your morning hangover. This is dangerous, although the external effect of relief occurs, but it is followed by very unpleasant consequences... The stimulating effect of green tea, combined with the residual alcohol contained in the body, can lead to neurosis, heart attack.
The claim that green tea removes the toxins produced by alcohol from the body is wrong. On the contrary, they begin to form with a vengeance. The diuretic effect of tea and alcohol leads to dehydration of the body, aggression, nervous excitement, and a decrease in vitality appear. And the frequent use of alcohol along with green tea accelerates the aging process of the skin, destroys the internal organs.
Green tea: effects on blood pressure
Tea has an active effect on blood pressure. They talk and write a lot about this. Some argue that green tea helps reduce blood pressure, while others say the opposite. Whom to believe? What does pressure tea do? After all, enough, how can he reduce the pressure?
In fact, however, in the golden mean. Tea regulates blood pressure. It has the amazing property of slightly gently lowering high pressure, and slightly increase the reduced. It all depends on individual characteristics organism. Observe how the body reacts to green tea. If the pressure has dropped too much after a cup of tea, it is better to give it up, especially if you are hypotonic. If after a cup good drink the occipital part of the head ached, no need to experiment, it is better to continue not to consume this drink, or to make it weak. It is better not to drink tea in large quantities for people with hypertensive and hypotensive patients.
Green tea and the digestive tract
The mucous membrane of the stomach and intestines is very sensitive to various drinks and foods. Green tea can have a negative effect on them if a person has chronic health problems:
- colitis;
- gastritis;
- stomach ulcer.
With increased acidity, it is recommended to limit the consumption of tea, it can be consumed in the form of one cup per day. With an ulcer, it is completely contraindicated. This is because green tea contains theophylline, a substance that prevents phosphoric acid from reducing stomach secretions. As a result, acidity only grows, it does not allow the formed ulcers to heal, pains appear, the disease worsens.
It is not recommended to drink green tea on an empty stomach. When it enters the body, it irritates the stomach lining, causing the release of gastric juice, causing nausea. Continuous drinking of tea on an empty stomach can trigger the development of gastritis.
Green tea is rich in organic acids: malic, succinic, oxalic, citric. They stimulate the production of bile. This is helpful in most cases, but the buildup of bile can cause diarrhea. There are people who are especially sensitive to caffeinated drinks, so you should drink green tea and watch your reaction, and if you experience diarrhea, stop drinking the drink.
Green tea can irritate the stomach and cause saliva to thin. To reduce it, you can drink it with milk.
Green tea and diabetes
To those who suffer diabetes mellitus, loves to abuse tea, you need to be more attentive to your body. According to scientists, if a person consumes green tea daily for more than a month, blood sugar decreases. But a one-time and periodic intake of a drink can increase sugar levels, increase the risk of developing the disease, and in sick people, reduce insulin sensitivity.
The harm of green tea for men
Research by Brazilian scientists has shown that active substances teas reduce testosterone levels. This can negatively affect men's health, semen production, and reproductive function.
Green tea and pregnancy
Green tea inhibits breakdown folic acid, and it is very important for the development of the brain of the future baby. This is because tea contains a substance called gallatepigallocatechin.
The caffeine in tea is useful, but not for pregnant women. Accumulated in a woman's body, it can lead to the birth of a baby with a reduced weight or premature birth... Caffeine causes heart palpitations, putting too much stress on the kidneys.
Green tea consumption rates
Of course, green tea is useful, but so that it does not cause side effects, did you harm? British scientists, after research, claim that up to six cups of green tea a day is a safe amount. Of these, 3-4 cups are beneficial, and the fifth will not be beneficial, but it will not cause harm either.
In the presence of chronic diseases, you should not risk it; it is better to reduce the amount of green tea to 2-3 cups a day. During the period of exacerbation of diseases - up to 1-2. If unpleasant consequences are noticed, discomfort in the diseased organ - refuse tea.
Harm from the wrong drink
"Wrong" tea can be obtained if you buy low-quality tea or brew good tea not properly. Green tea is very sensitive to water temperature. Boiling water can lead to the loss of all the beneficial substances of the tea leaf. Boiling water also makes the drink less tasty, with a bitter taste. The optimum temperature is 85-90 °.
You need to brew as much tea as will be drunk at a time. After a couple of hours, the brewed drink will lose its properties, turning into an ordinary infusion to quench thirst, and after 12 hours the tea leaves begin to produce toxic harmful substances, they accumulate in the body and cause harm.
Green tea, like other teas, is obtained from tea bush(tea or camellia chinese), which is a plant of the genus Camellia families Tea rooms. According to the name "Chinese camellia", one can make the correct conclusion that for the first time the tea bush began to be cultivated in China. From there he came to Japan, then the Dutch brought him to the island of Java, the British brought him to the Himalayas. After that, tea spread to India, Ceylon (now Sri Lanka), Indonesia, South America.
The difference between green tea and its more popular black "brother" lies in the processing of the tea leaf. Let's talk in more detail about how green tea is obtained.
Green tea production technology
Green tea production technology consists of the following stages: fixation (steaming), rolling, drying and sorting.
Fixation (steaming) is the treatment of a tea leaf with steam at a temperature of 170-180 ° C (Japanese method) or frying the tea leaf in braziers (hemispherical metal boilers), where it is heated to a temperature of 80-90 ° C (Chinese method). The purpose of this stage is the inactivation (elimination of activity) of enzymes and associated chemical transformations. In this way, main feature in the production of green tea lies in the fact that the fermentation process (oxidative reactions) in it is tried to be stopped, and not strengthened, as is the case with black tea. Steaming or roasting makes the tea leaf elastic, making it easy to curl. After the moisture content of the tea leaves has dropped to about 60%, the rolling stage begins.
The purpose of twisting is to crush the tissues of the leaf, after which cell sap is released on its surface.
After the rolling stage, the raw material is sent to drying. There the tea acquires an olive-green color, and its moisture content does not exceed 5%. Drying is carried out with hot air at a temperature of 95-105 ° C.
Sorting is the final stage of green tea production, which consists in grouping teas according to a homogeneous outward appearance(loose leaf tea or broken tea, tea leaf crumbs or sowing).
Important ingredients in green tea
Alkaloids
Green tea has in its chemical composition caffeine, the content of which is higher than in natural coffee. The amount of caffeine directly depends on the correctness of the tea production technology, as well as the initial growing conditions of the tea bush. Also green tea contains theobromine and theophylline.
Polyphenols
Up to 30% of the composition of green tea is polyphenols, in particular catechins, of which the greatest interest is epigallocatechin gallate. This tea also contains tannin, the content of which is 2 times higher than in its black counterpart.
Vitamins and minerals
Green tea also contains vitamins (P, C, A, B1, B2, B3, E, etc.) and minerals (calcium, fluorine, iron, iodine, potassium, phosphorus, magnesium, sodium, chromium, manganese, selenium, zinc, etc.).
The benefits of green tea
Green tea has gone through a lot of scientific and medical research, and to this day continues to generate interest in its properties, as well as its impact on human health. The results of these studies quite often contradict each other, but in general, the following can be said about green tea:
- The catechins found in green tea are actively absorbed by the lens and retina of the eye, resulting in oxidative stress in the eyes(the process of cell damage due to their oxidation) is reduced for up to 20 hours. Hong Kong scientists have concluded that green tea may be promising in preventing glaucoma.
- Studies in Slovenia have shown that green tea extract has antimicrobial activity.
- Epigallocatechin gallate helps protect brain cells. An experiment carried out at the Israel University of Technology on mice showed that given view catechin fights Parkinson's and Alzheimer's.
- Epigallocatechin gallate has been shown in the laboratory to inhibit the growth of cancer cells in prostate cancer. It is combined with tamoxifen suppresses the development of breast cancer (in vivo experiment, i.e. on a living organism was carried out on mice, in vitro experiment, i.e. in a test tube - on human cells).
- Green tea reduces the risk of developing memory and attention disorders by 2 times. The key to this effect, which has been confirmed in vivo in humans, may lie in the ability of epigallocatechin gallate to cross the blood-brain barrier.
- Green tea extract, containing polyphenols and caffeine, renews thermogenesis(heat release by the body) and stimulates fat oxidation. As a result, the metabolic rate increases. The number of heartbeats remains the same. Thanks to these properties, the risk of developing heart disease when drinking green tea is reduced. And this is confirmed by in vivo experience in people who have had acute myocardial infarction. With the use of green tea, the mortality rate among such people from a second heart attack has decreased by almost 2 times.
- By itself, drinking green tea does not lower cholesterol levels in the human body (although animal studies have shown the opposite). However, when added to green tea extract theaflavin(the pigment that gives dry tea leaves its characteristic shine) contained in black tea, the level of cholesterol in the human body is reduced.
- Green tea improves human immunity, and is also an energy stimulant (due to the active oxidation of fats).
- The systematic use of green tea leads to the normalization of a person's body weight.
- With a high content of antioxidants, green tea extract prevents skin aging and protects it from UV radiation.
- Despite the lack of scientific evidence that green tea can reduce the risk of developing stomach diseases, as well as help with existing problems associated with them, ethnoscience uses this tea as a remedy for dysentery, indigestion, and also attributes to it the ability to eliminate colitis.
- Science has not proven that green tea in any way affects respiratory diseases, but traditional medicine says that green tea can treat rhinitis, laryngitis, pharyngitis, stomatitis and conjunctivitis (in the form of rinsing and washing). The results of this treatment are unknown.
- As for dentistry, green tea contains fluoride, so rinsing your teeth and gums with green tea is a preventive measure against tooth decay.
- Thanks to the same catechins that reduce oxidative stress in muscles, green tea helps to tone the muscles in the body.
- Green tea can reduce the risk of contracting HIV. In addition, he is able to suspend the development of the disease in an infected person. These studies are only in the early stages and they are all associated with the same type of catechin called epigallocatechin gallate.
- Green tea lowers systolic and diastolic blood pressure when brewed correctly.
The harm of green tea
Excessive consumption of green tea due to its high content of catechins can lead to liver disease. Daily rate consumption of catechins - 500 mg. Many weight loss products are based on green tea extract and contain more than 700 mg of catechins in a single dose, which is a health hazard.
Also, excessive consumption of green tea can cause kidney complications (green tea contains purines and their derivatives). In addition, since green tea somewhat complicates the process of removing uric acid from the body, it is contraindicated for people suffering from rheumatoid arthritis and gout, as well as various diseases of the kidneys and gallbladder.
Green tea should not be consumed by people with increased nervous excitability.
Existing myths about green tea
- Green tea tones and soothes. Green tea either tones or soothes. If green tea is brewed for 1-2 minutes, it will lower blood pressure due to the minimal caffeine content. In this case, the water temperature should be 70-80 degrees. If green tea is infused for 6-9 minutes, brewing water at 80-90 degrees, we get a strong tonic, pressure-increasing drink.
- Green tea can be stored in a teapot for a day or more. Actually any tea must be drunk in 1 tea ceremony (for 1 reception). During the day, brewed tea turns into poison, because the minerals in its composition are completely oxidized.
- It is harmful to drink green tea with milk. It is not true. It is just that when tea is mixed with milk, the composition of the tea changes. Tannin forms chelate complexes with milk. This will simply make the tea less tonic.
- Coffee and green tea contain equal amounts of caffeine. This is not true. Green tea contains more caffeine than any type of coffee. This is partly due to the fact that a large amount of caffeine is lost during the processing of coffee beans.
- Green tea has hallucinogenic properties. This is pure fiction. Green tea can tone up, can relax. But it does not contain substances that can cause hallucinations.
