10 Evidence-Based Benefits of Green Tea
Written by Kris Gunnars, BSc — Medically reviewed by Atli Arnarson BSc, PhD — Updated on April 6, 2020
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Green tea is touted to be one of the healthiest beverages on the planet.
It’s loaded with antioxidants that have many health benefits, which may include:
improved brain function
protecting against cancer
lowering the risk of heart disease
There may be even more potential health benefits.
Here are 10 possible health benefits of green tea.
- Contains healthy bioactive compounds
Green tea is more than just a hydrating beverage.
The green tea plant contains a range of healthy compounds that make it into the final drink.
Tea is rich in polyphenols, which are natural compounds that have health benefits, such as reducing inflammation and helping to fight cancer.
Green tea contains a catechin called epigallocatechin-3-gallate (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 play a role in aging and many types of diseases.
EGCG is one of the most powerful compounds in green tea. Research has tested its ability to help treat various diseases. It appears to be one of the main compounds that gives green tea its medicinal properties.
Green tea also has small amounts of minerals that can benefit your health.
Try to choose a higher quality brand of green tea, because some of the lower quality brands can contain excessive amounts of fluoride.
That being said, even if you choose a lower quality brand, the benefits still outweigh any risk.
Green tea is loaded with polyphenol antioxidants, including a catechin called EGCG. These antioxidants can have various beneficial effects on health.
- May improve brain function
Green tea does more than just keep you alert, it may also help boost brain function.
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 taking in too much caffeine.
Caffeine affects the brain by blocking an inhibitory neurotransmitter called adenosine. This way, it increases the firing of neurons and the concentration of neurotransmitters like dopamine and norepinephrine.
Research has consistently shown that caffeine can improve various aspects of brain function, including mood, vigilance, reaction time, and memory.
However, caffeine isn’t the only brain-boosting compound in green tea. It also contains amino acid L-theanine, which can cross the blood-brain barrier.
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.
Studies show that caffeine and L-theanine can have synergistic effects. This means that the combination of the two can have particularly powerful effects in improving brain function.
Because of the L-theanine and the small dose of caffeine, green tea may 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 with coffee.
Green 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.
- Increases fat burning
If you look at the ingredients list for any fat burning supplement, chances are, green tea will be on there.
This is because, according to research, green tea can increase fat burning and boost metabolic rate.
In one study involving 10 healthy men, taking green tea extract increased the number of calories burned by 4%. In another involving 12 healthy men, green tea extract increased fat oxidation by 17%, compared with those taking a placebo.
However, some studies on green tea don’t show any increase in metabolism, so the effects may depend on the individual and how the study was set up.
Caffeine may also improve physical performance by mobilizing fatty acids from fat tissue and making them available for use as energy.
Two separate review studies reported that caffeine may increase physical performance by approximately 11–12%.
Green tea may boost metabolic rate and increase fat burning in the short term, although not all studies agree.
- Antioxidants may lower the risk of some cancers
Cancer is caused by uncontrolled growth of cells. It’s one of the world’s leading causes of death.
Research has shown that oxidative damage can lead to chronic inflammation, which can lead to chronic diseases, including cancers. Antioxidants can help protect against oxidative damage.
Green tea is an excellent source of powerful antioxidants.
Research has linked green tea compounds with a reduced risk of cancer, including the following studies:
Breast cancer. A comprehensive review of observational studies found that women who drank the most green tea had an approximately 20–30% lower risk of developing breast cancer, one of the most common cancers in women.
Prostate cancer. One study observed that men drinking green tea had a lower risk of advanced prostate cancer.
Colorectal cancer. An analysis of 29 studies showed that those drinking green tea were around 42% less likely to develop colorectal cancer.
Many observational studies indicate that green tea drinkers are less likely to develop several types of cancer, but more high quality research is needed to confirm these effects.
To get the most health benefits, avoid adding milk to your tea. Some studies suggest it can reduce the antioxidant value in some teas.
Green 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.
- May protect the brain from aging
Not only can green tea improve brain function in the short term, it may also protect your brain as you age.
Alzheimer’s disease is a common neurodegenerative disease and the most common cause of dementia in older adults.
Parkinson’s disease is another common neurodegenerative disease and involves the death of dopamine-producing neurons in the brain.
Several studies show that the catechin compounds in green tea can have various protective effects on neurons in test tubes and animal models, possibly lowering the risk of dementia.
The bioactive compounds in green tea can have various protective effects on the brain. They may reduce the risk of dementia, a common neurodegenerative disorder in older adults.
- May reduce bad breath
The catechins in green tea also have benefits for oral health.
Test-tube studies suggest that catechins can suppress the growth of bacteria, potentially lowering the risk of infections.
Streptococcus mutans is a common bacterium in the mouth. It causes plaque formation and is a leading contributor to cavities and tooth decay.
Studies indicate that the catechins in green tea can inhibit the growth of oral bacteria in the lab, but no evidence shows that drinking green tea has similar effects.
However, there’s some evidence that green tea may reduce bad breath.
The catechins in green tea may inhibit the growth of bacteria in the mouth, reducing the risk of bad breath.
- May help prevent type 2 diabetes
The rates of type 2 diabetes are increasing in recent decades. The condition now affects about 1 in 10 Americans.
Type 2 diabetes involves having elevated blood sugar levels, which may be caused by insulin resistance or an inability to produce insulin.
Studies show that green tea may improve insulin sensitivity and reduce blood sugar levels.
One study in Japanese individuals found that those who drank the most green tea had an approximately 42% lower risk of type 2 diabetes.
According to a review of 7 studies with a total of 286,701 individuals, tea drinkers had an 18% lower risk of diabetes.
Some controlled studies show that green tea may cause mild reductions in blood sugar levels. It may also lower the risk of type 2 diabetes.
- May help prevent cardiovascular disease
Cardiovascular diseases, including heart disease and stroke, are the leading causes of death worldwide.
Studies show that green tea may improve some of the main risk factors for these diseases, which includes improving total cholesterol and LDL (bad) cholesterol levels.
Green tea also increases the antioxidant capacity of the blood, which protects the LDL particles from oxidation, which is one part of the pathway toward heart disease.
Given the beneficial effects on risk factors, it may not be surprising that people who drink green tea have up to a 31% lower risk of dying from a cardiovascular disease.
Green tea may lower total and LDL (bad) cholesterol, as well as protect the LDL particles from oxidation. Studies show that people who drink green tea have a lower risk of cardiovascular disease.
- May help you lose weight
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 may help reduce body fat, especially in the abdominal area.
One of these studies was a 12-week randomized controlled study involving 240 people with obesity.
In this study, those in the green tea group had significant decreases in body fat percentage, body weight, waist circumference, and belly fat, compared with those in the control group.
However, some studies don’t show a statistically significant increase in weight loss with green tea, so researchers need to perform further studies to confirm this effect.
Some studies show that green tea may lead to increased weight loss. It may be particularly effective at reducing the dangerous abdominal fat.
- May help you live longer
Given that some compounds in green tea may help protect against cancer and heart disease, it makes sense that it could help you live longer.
In one study, researchers studied 40,530 Japanese adults over 11 years. Those who drank the most green tea — 5 or more cups per day — were significantly less likely to die during the study period.
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 involving 14,001 older Japanese individuals found that those who drank the most green tea were 76% less likely to die during the 6-year study period.
Studies show that people who drink green tea may live longer than those who don’t.
The bottom line
Green tea has a range of possible health benefits.
To help you feel better, lose weight, and lower your risk of chronic diseases, you may want to consider making green tea a regular part of your life.
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