Green tea is the healthiest beverage on the planet.
It is loaded with antioxidants and nutrients that have powerful effects on the body.
This includes improved brain function, fat loss, a lower risk of cancer and many other incredible benefits.
Here are 10 health benefits of green tea that have been confirmed in human research studies.
1. Green Tea Contains Various Bio-Active Compounds That Can Improve Health
Green tea is more than just green liquid.
Many of the bio-active compounds in the tea leaves do make it into the
final drink, which contains large amounts of important nutrients. It is
loaded with
polyphenols like flavonoids and catechins, which function as powerful antioxidants (
1).
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.
One of the more powerful compounds in green tea is the antioxidant
Epigallocatechin Gallate (EGCG),
which has been studied to treat various diseases and may be one of the
main reasons green tea has such powerful medicinal properties.
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 levels of fluoride (
2). That being said, even if you choose a lower quality brand, the benefits still far outweigh any risk.
Bottom Line: Green tea is loaded with bioactive compounds that can have various beneficial effects on health.
2. Compounds in Green Tea Can Improve Brain Function and Make You Smarter
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 (
3,
4).
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 (
5).
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 (
6).
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 (
7,
8,
9).
Studies show that caffeine and L-theanine can have synergistic
effects. Thecombination of the two is particularly potent at improving
brain function (
10,
11).
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.
Bottom Line: 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.
3. Green Tea Increases Fat Burning and Improves Physical Performance
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 (
12,
13).
In one study in 10 healthy men, green tea increased energy expenditure by 4% (
14).
Another study showed that fat oxidation was increased by 17%,
indicating that green tea may selectively increase the burning of fat (
15).
However, I’d like to point out that some studies on green tea don’t
show any increase in metabolism, so the effects may depend on the
individual (
16).
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 (
17,
18). In two separate review studies, caffeine has been shown to increase physical performance by 11-12%, on average (
19,
20).
Bottom Line: Green tea has been shown to boost
the metabolic rate and increase fat burning in the short term, although
not all studies agree.
4. Antioxidants in Green Tea May Lower Your Risk of Various Types of Cancer
Cancer is caused by uncontrolled growth of cells. It is one of the
world’s leading causes of death. It is well known that oxidative damage
contributes to the development of cancer and that antioxidants can have a
protective effect (
21).
Green tea is an excellent source of powerful antioxidants, so it
makes perfect 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 22% lower risk of
developing breast cancer, the most common cancer in women (22).
- 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 (23).
- Colo-rectal cancer: A study of 69,710 Chinese women found that green tea drinkers had a 57% lower risk of colo-rectal cancer (24).
Multiple other observational studies show that green tea drinkers are significantly less likely to get various types of cancer (
25,
26,
27). It is important to keep in mind that it may be a bad idea to put
milk in your tea, because it can reduce the antioxidant value (
28).
Bottom Line: 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.
5. Green Tea May Protect Your Brain in Old Age, Lowering Your Risk of Alzheimer’s and Parkinson’s
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 neuro-degenerative disease in humans and a leading cause of
dementia.
Parkinson’s disease is the second most common neuro-degenerative
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 (
29,
30,
31).
Bottom Line: The bio-active compounds in green
tea can have various protective effects on neurons and may reduce the
risk of both Alzheimer’s and Parkinson’s, the two most common
neuro-degenerative disorders.
6. Green Tea Can Kill Bacteria, Which Improves Dental Health and Lowers Your Risk of Infection
The
catechins in
green tea have other biological effects as well. Some studies show that
they can kill bacteria and inhibit viruses like the influenza virus,
potentially lowering your risk of infections (
32,
33,
34,
35).
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 (
36,
37,
38,
39,
40,
41).
Another awesome benefit of green tea… multiple studies show that it can reduce bad breath (
42,
43).
Bottom Line: The 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.
7. Green Tea May Lower Your Risk of Type II Diabetes
Type II
diabetes is a disease that has reached epidemic proportions in the past few decades and now afflicts about 300 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 (
44,
45).
One study in Japanese individuals found that those who drank the most
green tea had a 42% lower risk of developing type II diabetes (
46).
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 (
47).
Bottom Line: Some controlled trials show that
green tea can cause mild reductions in blood sugar levels. It may also
lower the risk of developing type II diabetes in the long term.
8. Green Tea May Reduce Your Risk of Cardiovascular Disease
Cardiovascular diseases, including heart disease and stroke, are the biggest causes of death in the world (
48). Studies show that green tea can improve some of the main risk factors for these diseases.
This includes total
cholesterol, LDL cholesterol and triglycerides (
49).
Green tea also dramatically increases the antioxidant capability of the
blood, which protects the LDL cholesterol particles from oxidation,
which is one part of the pathway towards heart disease (
50,
51,
52).
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 (
53,
54,
55).
Bottom Line: Green 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.
9. Green Tea Can Help You Lose Weight and Lower Your Risk of Becoming Obese
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 (
56,
57,
58).
One of these studies was a randomized controlled trial in 240 men and
women that went on for 12 weeks. In this study, the green tea group had
significant decreases in body fat percentage, body weight, waist
circumference and abdominal fat (
59).
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 (
60).
Bottom Line: Some studies show that green tea
leads to increased weight loss. It is particularly effective at reducing
the dangerous abdominal fat.
10. Green Tea May Decrease Your Risk of Dying and Help You Live Longer
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 (
61):
- 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 65-84
years found that those who drank the most green tea were 76% less likely
to die during the 6 year study period (
62).
Take Home Message
If you want to feel better, lose weight and lower your risk of
chronic diseases, then you might want to consider making green tea a
regular part of your life.
