Green tea contains nutrients and antioxidants that provide many health benefits – from preventing cancer to improving brain function. Read this article to learn all about this nutritional drink.

What is Green Tea?

Green tea contains polyphenols and catechins, which are micronutrients found naturally in our foods that can act as antioxidants.

Epigallocatechin gallate (EGCG) is the main polyphenol found in green tea and is known to have many beneficial effects on human health. The polyphenols can reduce the formation of free radicals, which play a role in diseases. This protects cells and molecules from damage. There are also minerals found in green tea that are important for health [R].

L-theanine is also found in green tea, and it is especially good for the brain.

Because there are no known health risks associated with green tea and no toxic level, green tea is a great way to help you become a healthier person [R].

EGCG Snapshot


  • Antioxidants found in green tea can help prevent cancer
  • EGCG promotes brain health and defends against Parkinson’s and Alzheimer’s Disease
  • EGCG protects the heart
  • It protects against inflammation
  • Drinking green tea can help you lose weight


  • The caffeine found in green tea can lead to anxiety, heart rate problems, etc. if you drink too much
  • It might lower testosterone levels

Health Benefits of Green Tea

1) Antioxidants Found in Green Tea Can Lower Your Cancer Risk

Oxidative damage is known to cause various cancers in the body, so the many antioxidants found in green tea help lower your risk [R].

Many studies have been done on the antioxidant properties of green tea and it has been shown that green tea lowers the risk of breast, prostate, and colon cancer in humans [R, R, R].

The polyphenols found in green tea prevents cancer from growing by regulating cancer cell growth, survival, and metastasis. It affects the cancer cells at the DNA, RNA, and protein levels [R].

2) Green Tea Promotes Brain Health

The EGCG, caffeine, and L-theanine all work to improve brain function and health.

The amount of caffeine found in green tea is enough to help improve memory and reaction time. It also increases the amount of dopamine and norepinephrine in the brain [R].  

EGCG and L-theanine both increase memory and attention in patients with mild brain damage [R].

L-theanine also has anti-anxiety effects and can help you calm down [R].

On the other hand, EGCG was proven to reduce fatigue [R].  It can refresh and relax your brain [R]. 

The polyphenols found in the brain also protects neurons and help protect against dementia, Alzheimer’s, and Parkinson’s disease [R].

Green tea also reduced depressive symptoms and increased reward learning [R].

3) Green Tea Helps You Lose Weight

Green tea can help you lose weight in many ways.

It has been shown to increase your metabolism and help burn more fat [R].

Green tea suppresses appetite and leads to less energy consumption [R].

Green tea also interacts with other compounds that burn fat as well as adrenaline to increase the body’s metabolic rate [R].

EGCG suppresses an enzyme that breaks down norepinephrine, so this increases the amount of norepinephrine in the body. This hormone signals for more fat cells to be broken down, which can now be used as energy [R].

In addition to these properties, green tea can increase your endurance. The exhaust time for patients that drink green tea was extended. This means that you can exercise for a longer time and be able to lose more weight [R]

Consumption of green tea also decreases carbohydrate consumption as well as block fat absorption [R].

In a study done on overweight and obese women, green tea consumption resulted in more weight loss [R].

4) EGCG Reduces Heart Disease Risk

Polyphenols found in green tea can reduce cholesterol, which is the main factor of heart disease [R].

Green tea also lowers blood pressure by increasing blood flow in the body [R].

5) Green Tea Lowers Risk of Diabetes

Catechins in green tea can help reduce your risk for Type II Diabetes by improving insulin sensitivity [R].

This then lowers blood glucose levels [R].

6) Green Tea Fights Against Bacterial Infections

Green tea acts as an antimicrobial agent. Its properties can reduce bacteria spores in the body [R].

EGCG damages bacterial membrane and fights against infections [R]

Mouthwash with green tea in it also reduced plaque and gingivitis [R].  

7) EGCG Has Anti-Inflammatory Effects

Polyphenols found in green tea helped prevent inflammation due to UV rays [R].   

EGCG also prevents and treats inflammation due to rheumatoid arthritis [R].

8) EGCG Improves Liver Health

Polyphenols in green tea can help improve liver health. It lowers lipid levels in the body and reduces the risk for non-alcoholic fatty liver disease [R].

9) EGCG Helps Skin

EGCG has anti-wrinkle effects and also reduced redness in the skin [R].

10) EGCG Prevents Baldness

EGCG helps to prevent baldness. The polyphenols in green tea can stimulate human hair growth [R].

11) EGCG Promotes Dental Health

EGCG helps oral defense mechanisms and can prevent gingivitis. It provides additional protection against oxidative stress in the mouth [R].

The polyphenol also helps enhance the activity of dental adhesives [R].

12) EGCG Prevents Osteoporosis

EGCG  promotes osteoclast and osteoblast growth in bone cells. EGCG can be used in stem cell research to help prevent osteoporosis [R].

13) Green Tea Can Help You Live Longer

Polyphenols in green tea protect telomeres from damage. Telomere damage can affect your biological age and increase disease risk. Thus, polyphenols can help prevent aging [R, R].

Finally, all of the benefits that green tea and EGCG offers will make your life healthier, which can also boost your longevity [R].

EGCG could prevent telomere shortening [R].


Green tea increases N-acetyl aspartate [R], which can help with intelligence.

Green tea may lower thyroid function [R].

Interactions With Other Nutrients

  • Fish Oil and Fish: Fish oil worked together with catechins in green tea to increase fat and glucose metabolism while nutrients found in fish helped lower blood pressure [R].
  • Ubiquinone: This supplement helps to increase the effectiveness of EGCG’s antioxidant properties [R].
  • Curcumin: Curcumin works together with EGCG to reduce tumor progression in colon cells [R].
  • Vitamin C: This vitamin works with green tea to reduce cancer risk [R].
  • Capsicum vanilloids: Found in hot peppers, capsicum vanilloids help fight against cancer by increasing cell killing ability [R]
  • Vitamin E: Coupled with Vitamin E, green tea polyphenols improved exercise capacity, lowered glucose levels, and reduced body weight [R].

Side Effects & Risks

Harmful effects of tea overconsumption (black or green) are due to a few main factors [R]:

  • Its caffeine content
  • The presence of aluminum [R, R]
  • The inhibition of iron absorption by tea polyphenols [R]
  • Toxicity to the liver in high dosages

If you drink too much, the caffeine found in green tea can lead to anxiety, heart rate problems, etc. L-theanine found in green tea can also cause dizziness, headaches, and digestive problems [RR].

In rats, green tea consumption lowered testosterone levels by 20% and sperm count by 2%. This might affect reproduction [R].

There is a risk of liver toxicity if too much EGCG is taken, but it is rare. There was an individual reported to have liver failure from taking EGCG supplements [R, RR].

Higher intake of green tea might cause oxidative DNA damage of hamster pancreas and liver [R].

EGCG acts as a pro-oxidant, rather than an antioxidant, in pancreatic insulin-secreting cells. Therefore, high intake of green tea may be detrimental for diabetic animals [].

At a high dose (5% of diet for 13 wk), green tea extract induced a thyroid enlargement (goiter) in normal rats [R]. This high-level treatment altered concentrations of thyroid hormones. However, drinking even a very high dietary amount of green tea would be unlikely to cause these adverse effects in humans.

Green tea should not be taken by patients suffering from heart conditions or major cardiovascular problems. Pregnant and breastfeeding women should drink no more than one or two cups per day because caffeine can cause an increase in heart rhythm.

Caution should be taken if an individual is taking a diuretic drug (as a result of caffeine’s diuretic effects).

Some studies revealed the capacity of tea plants to accumulate high levels of aluminum [R, R]. This aspect is important for patients with kidney failure or those with neurological diseases, because aluminum can be accumulated in the brain.

Because of the rare risk of liver failure, we don’t recommend taking more than 1 capsule of the extract, or 400mg of EGCG.


Do not exceed 400mg of EGCG per a day, as more has been associated with liver issues.

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