Green tea is more than just liquid.
Many of the plant compounds in the tea leaves do make it into the final drink, which contains large amounts of important nutrients (1Trusted Source).
Tea is rich in polyphenols that have effects like reducing inflammation and helping to fight cancer.
Green tea is about 30 percent polyphenols by weight, including large amounts of a catechin called EGCG. Catechins are natural antioxidants that help prevent cell damage and provide other benefits.
These substances can reduce the formation of free radicals in the body, protecting cells and molecules from damage. These free radicals are known to play a role in aging and all sorts of diseases.
EGCG (Epigallocatechin Gallate) is one of the most powerful compounds in green tea. It has been studied to treat various diseases and may be one of the main reasons green tea has such powerful medicinal properties (2Trusted Source).
Green tea also has small amounts of minerals that are important for health.
Try to choose a higher quality brand of green tea, because some of the lower quality brands can contain excessive amounts of fluoride (3Trusted Source).
That being said, even if you choose a lower quality brand, the benefits still far outweigh any risk.
SUMMARYGreen tea is loaded with polyphenol antioxidants, including a catechin called EGCG. These antioxidants can have various beneficial effects on health.
Green tea does more than just keep you awake, it can also make you smarter.
The key active ingredient is caffeine, which is a known stimulant.
It doesn’t contain as much as coffee, but enough to produce a response without causing the “jittery” effects associated with too much caffeine.
What caffeine does in the brain is to block an inhibitory neurotransmitter called Adenosine. This way, it actually increases the firing of neurons and the concentration of neurotransmitters like dopamine and norepinephrine (4Trusted Source, 5).
Caffeine has been intensively studied before and consistently leads to improvements in various aspects of brain function, including improved mood, vigilance, reaction time and memory (6).
However, green tea contains more than just caffeine. It also has the amino acid L-theanine, which is able to cross the blood-brain barrier (7Trusted Source).
L-theanine increases the activity of the inhibitory neurotransmitter GABA, which has anti-anxiety effects. It also increases dopamine and the production of alpha waves in the brain (7Trusted Source, 8Trusted Source, 9Trusted Source).
Studies show that caffeine and L-theanine can have synergistic effects. The combination of the two is particularly potent at improving brain function (10Trusted Source, 11Trusted Source).
Because of the L-theanine and the smaller dose of caffeine, green tea can give you a much milder and different kind of “buzz” than coffee.
Many people report having more stable energy and being much more productive when they drink green tea, compared to coffee.
SUMMARYGreen tea contains less caffeine than coffee, but enough to produce an effect. It also contains the amino acid L-theanine, which can work synergistically with caffeine to improve brain function.
If you look at the ingredients list for any fat burning supplement, chances are that green tea will be on there.
This is because green tea has been shown to increase fat burning and boost the metabolic rate, in human controlled trials (12Trusted Source).
In one study in 10 healthy men, green tea increased energy expenditure by 4% (13Trusted Source).
Another study showed that fat oxidation was increased by 17%, indicating that green tea may selectively increase the burning of fat (14Trusted Source).
However, some studies on green tea don’t show any increase in metabolism, so the effects may depend on the individual (15Trusted Source).
Caffeine itself has also been shown to improve physical performance by mobilizing fatty acids from the fat tissues and making them available for use as energy (16Trusted Source, 17Trusted Source).
In two separate review studies, caffeine has been shown to increase physical performance by 11-12%, on average (18, 19Trusted Source).
SUMMARYGreen tea has been shown to boost the metabolic rate and increase fat burning in the short term, although not all studies agree.
Cancer is caused by uncontrolled growth of cells. It is one of the world’s leading causes of death.
It is known that oxidative damage contributes to the development of cancer and that antioxidants may have a protective effect (20Trusted Source).
Green tea is an excellent source of powerful antioxidants, so it makes sense that it could reduce your risk of cancer, which it appears to do:
- Breast cancer: A meta-analysis of observational studies found that women who drank the most green tea had a 20-30% lower risk of developing breast cancer, the most common cancer in women (21Trusted Source).
- Prostate cancer: One study found that men drinking green tea had a 48% lower risk of developing prostate cancer, which is the most common cancer in men (22Trusted Source).
- Colorectal cancer: An analysis of 29 studies showed that those drinking green tea were up to 42% less likely to develop colorectal cancer (23Trusted Source).
Many observational studies have shown that green tea drinkers are less likely to develop several types of cancer. However, more high-quality research is needed to confirm these effects (24, 25Trusted Source).
It is important to keep in mind that it may be a bad idea to put milk in your tea, because some studies suggest it reduces the antioxidant value (26Trusted Source).
SUMMARYGreen tea has powerful antioxidants that may protect against cancer. Multiple studies show that green tea drinkers have a lower risk of various types of cancer.
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Not only can green tea improve brain function in the short term, it may also protect your brain in old age.
Alzheimer’s disease is the most common neurodegenerative disease in humans and a leading cause of dementia.
Parkinson’s disease is the second most common neurodegenerative disease and involves the death of dopamine producing neurons in the brain.
Multiple studies show that the catechin compounds in green tea can have various protective effects on neurons in test tubes and animal models, potentially lowering the risk of Alzheimer’s and Parkinson’s (27Trusted Source, 28Trusted Source, 29Trusted Source).
SUMMARYThe bioactive compounds in green tea can have various protective effects on the brain. They may reduce the risk of both Alzheimer’s and Parkinson’s, the two most common neurodegenerative disorders.
The catechins in green tea also have other biological effects.
Some studies show that they can kill bacteria and inhibit viruses like the influenza virus, potentially lowering your risk of infections (30Trusted Source, 31, 32Trusted Source, 33Trusted Source).
Streptococcus mutans is the primary harmful bacteria in the mouth. It causes plaque formation and is a leading contributor to cavities and tooth decay.
Studies show that the catechins in green tea can inhibit the growth of Streptococcus mutans. Green tea consumption is associated with improved dental health and a lower risk of caries (34Trusted Source, 35Trusted Source, 36Trusted Source, 37Trusted Source).
Multiple studies also show that green tea can reduce bad breath (38Trusted Source, 39).
SUMMARYThe catechins in green tea may inhibit the growth of bacteria and some viruses. This can lower the risk of infections and lead to improvements in dental health, a lower risk of caries and reduced bad breath.
Type 2 diabetes is a disease that has reached epidemic proportions in the past few decades and now afflicts about 400 million people worldwide.
This disease involves having elevated blood sugar levels in the context of insulin resistance or an inability to produce insulin.
Studies show that green tea can improve insulin sensitivity and reduce blood sugar levels (40Trusted Source).
One study in Japanese individuals found that those who drank the most green tea had a 42% lower risk of developing type 2 diabetes (41Trusted Source).
According to a review of 7 studies with a total of 286,701 individuals, green tea drinkers had an 18% lower risk of becoming diabetic (42Trusted Source).
SUMMARYSome controlled trials show that green tea can cause mild reductions in blood sugar levels. It may also lower the risk of developing type 2 diabetes.
Cardiovascular diseases, including heart disease and stroke, are the biggest causes of death in the world (43).
Studies show that green tea can improve some of the main risk factors for these diseases.
This includes total cholesterol, LDL cholesterol and triglycerides (44Trusted Source).
Green tea also dramatically increases the antioxidant capacity of the blood, which protects the LDL particles from oxidation, which is one part of the pathway towards heart disease (45, 46).
Given the beneficial effects on risk factors, it is not surprising to see that green tea drinkers have up to a 31% lower risk of cardiovascular disease (47, 48, 49Trusted Source).
SUMMARYGreen tea has been shown to lower total and LDL cholesterol, as well as protect the LDL particles from oxidation. Observational studies show that green tea drinkers have a lower risk of cardiovascular disease.
Given that green tea can boost the metabolic rate in the short term, it makes sense that it could help you lose weight.
Several studies show that green tea leads to decreases in body fat, especially in the abdominal area (50, 51Trusted Source).
One of these studies was a 12-week randomized controlled trial in 240 men and women. In this study, the green tea group had significant decreases in body fat percentage, body weight, waist circumference and belly fat (52).
However, some studies don’t show a statistically significant increases in weight loss with green tea, so this needs to be taken with a grain of salt (53Trusted Source).
SUMMARYSome studies show that green tea leads to increased weight loss. It may be particularly effective at reducing the dangerous abdominal fat.
Of course, we all have to die eventually. That is inevitable.
However, given that green tea drinkers are at a lower risk of cardiovascular disease and cancer, it makes sense that it could help you live longer.
In a study of 40,530 Japanese adults, those who drank the most green tea (5 or more cups per day) were significantly less likely to die during an 11 year period (54Trusted Source):
- Death of all causes: 23% lower in women, 12% lower in men.
- Death from heart disease: 31% lower in women, 22% lower in men.
- Death from stroke: 42% lower in women, 35% lower in men.
Another study in 14,001 elderly Japanese individuals aged found that those who drank the most green tea were 76% less likely to die during the 6 year study period (55).