Is green tea useful? And if "yes, to whom and how much?
This drink has been used since ancient times to get rid of depression and headaches, and modern people also note its ability to burn fat, lower blood pressure and levels of bad LDL-cholesterol in the blood.
Today we will examine in detail the beneficial properties of green tea for the human body, the correct ways of brewing it and individual cases in which its use can harm your health.
Before you know what the benefits of green tea really are and what the contraindications are for it, check out these interesting facts:
- Green tea is extracted from the same plant as black tea. It is called a tea bush or Chinese camellia. About 3/4 of the leaves from these bushes end up with black tea, 20-22% green, and less than 2% of them with oolong tea.
- Green tea is green because it is not fermented. This means that during the processing it is subjected to minimal oxidation and the active ingredients in its composition remain intact.
- It contains caffeine.
- A 99% cup of green tea is made up of water, so this drink is great for hydrating the body. For the same reason, the use of tea directly depends on the quality of the water you brew.
- In its purest form, green tea does not contain fats and sugars, and is very low in calories. Adding sugar does not destroy nutrients in green tea, but increases calories and reduces the overall usefulness of the drink.
The benefits and harms of green tea to the body. What does this drink contain?
Green tea is a rich source of potassium, vitamin C and some B vitamins that dissolve well in water and are absorbed by our body. Another important component of green tea is the antioxidants of flavonoids, including proanthocyanidins, which actively fight age-related diseases, diseases of the circulatory and digestive systems.
Figure Source: U.S. National Nutrient Database for Standard Reference. The figures characterize regular, water-brewed green tea and can vary slightly depending on the variety and conditions of growing the product.
Antioxidants in green tea and their effect on the body
Green tea is quite high in plant antioxidants - flavonoids and catechins, the most active of which is epigallocatechin gallate or EGCG. It is a very powerful antioxidant, which according to many scientists is able to slow the growth of cancer cells and the aging of the body. Along with other antioxidants in green tea, including proanthocyanidins, it also helps:
- To facilitate digestion and speed up metabolism in the body;
- Reduce blood pressure and LDL cholesterol in the blood;
- Refresh your breath and eliminate bacteria that cause tooth decay and other oral diseases.
Warning: To date, not enough clinical trials have been conducted to make it possible to use green tea or its extracts with full confidence in the treatment of cancer and cardiovascular disease. For example, experiments that confirmed the ability of green tea to reduce the risk of liver cancer were conducted only in the Chinese and Japanese population.
However, studies conducted in 2015 in broad groups of men and women found a direct link between daily consumption of 1 cup of green tea and a 5% reduction in the risk of death from cardiovascular disease, as well as a 4% reduction in the risk of death from any cause.
Yet modern data on how green tea affects different people with their individual characteristics remain fairly limited. Before using it for medicinal purposes, be sure to consult with your doctor and observe the recommended dose.
Caffeine in green tea - good or harmful?
A cup of green tea contains an average of about 30 mg of caffeine. By comparison, black tea contains an average of 55 mg, Red Bull contains 75 mg, and regular coffee contains 90 mg of caffeine per cup of 250 mg. How does this affect a person?
It is known that caffeine has an exciting effect on the brain, gives a sense of strength and lifts the mood. However, the antioxidant EGCG and L-tianin in green tea to some extent neutralize the effect of caffeine and make this drink much safer. L-theanine is one of the few amino acids that reduces anxiety, lowers blood pressure, relaxes, improves learning ability and boosts immunity. Therefore, a cup of green tea can always be drunk in the evening without fear of insomnia.
Note: with the usual way of brewing tea, we get quite a small amount of L-tiyanine. To completely release it into the drink, the first brewing of green tea is drained, after which the leaves are boiled at a high water temperature up to 127 degrees Celsius.
It is also necessary to pay attention to the fact that caffeine contributes to dehydration of the body and is considered a good diuretic. There are studies that have shown that catechins in green tea do not allow caffeine to dehydrate the body. However, many people have noticed that after drinking tea begin to run more often to the toilet. So just listen to your body and do not abuse this drink, if it similarly affects you.
Finally, many scientists consider caffeine in green tea safe and even gave it the status of GRAS (certainly safe products and ingredients). In any case, today green tea remains the safest and most useful of all caffeine-containing beverages.
Green tea: raises or lowers pressure?
Because of the caffeine content, quite often the question arises: green tea increases or lowers the pressure? Above, we have already mentioned that L-tianin neutralizes the action of caffeine, but the amount of this amino acid in the drink directly depends on the way it is brewed. There are also catechins in it, which have a beneficial effect on the heart and blood vessels. What is the effect of green tea in general?
All the experiments have yielded one result: green tea lowers the pressure. The cumulative benefits of green tea for hypertension are obvious! A general meta-analysis of studies showed that systematic consumption of green tea for 3-6 months reduced systolic and diastolic pressure by about 3 mmHg. Art.
Does green tea really help to lose weight?
No global experiments confirming the use of green tea in weight loss have been conducted yet. However, there are a number of facts that support this assertion:
- Green tea has the ability to accelerate metabolic processes, which causes the human body to spend calories faster without any exercise.
- Green tea is not able to suppress appetite, but allows for time to increase the endurance of the body. Polyphenols in its composition accelerate thermogenesis (producing heat by our body to keep all its systems running) and promote the use of calories as energy.
- Catechins in green tea help to regulate blood sugar levels and prevent obesity by preventing the deposition of glucose in fat cells.
- The caffeine we mentioned above interacts well with polyphenols and also increases the rate of fat burning.
Slowly but surely green tea helps to lose weight, causing the human body to lose fat, but while maintaining muscle mass.
Possible harm to green tea for the human body
Moderate regular consumption of green tea is generally considered safe, but there are still some limitations and counter-indications.
Thus, green tea can be toxic to the liver when exceeding the recommended consumption standards (10-29 mg of tea per 1 kg of weight per day). In addition, too high doses of green tea, which contains many antioxidants, can begin to act as a prooxidant and damage the body's healthy cells.
Heartburn and indigestion are frequent consequences of excessive consumption and/or improper brewing of green tea. This harm can be prevented by brewing a drink on water with a temperature much lower than the boiling point. Ideally in the range of 71-82 degrees Celsius.
Green tea can also be contraindicated in the following cases:
- Iron deficiency anemia. Consumption of green tea can create a deficiency of iron in your body, which strongly affects people suffering from anaemia. This harmful property of tea can be neutralized by adding lemon to it.
- allergy. It is extremely rare, but still some people have an allergic reaction to Chinese green tea: throat swelling, shortness of breath, swelling of lips, tongue and/or face, elevated body temperature.
- Caffeine sensitivity. With excessive consumption or increased sensitivity to caffeine, green tea can cause anxiety, strong heartbeat, irritability, sleep problems, etc.
- pregnancy. Green tea is not recommended to be consumed in large quantities by pregnant women, especially in the early stages. Caffeine, tannins and catechins in its composition can lead to birth defects.
- Taking medication. When taking medicines, be sure to consult your doctor about your consumption of green tea.
How much green tea can you drink per day
Of course, the benefit of green tea depends on the amount you consume. Experts recommend drinking 10 to 29 mg of green tea per 1 kg of weight per day. Thus, for a person weighing 60 kg the recommended dose is within 600-1740 mg (from 2 to 6 cups), and for a person weighing 85 kg - within 850-2465 mg (3-9 cups). However, given the available contraindications and research data, it is better not to bring the amount of tea drunk per day to the upper limit. According to several experiments, the dose of 6 cups of green tea is too large for normal daily consumption. Side effects of this intake may be frequent urination (and, as a result, dehydration), diarrhea, vomiting, dizziness, headaches and loss of appetite.
Be healthy!