Green Tea: 13 Health Benefits, Side Effects & How to Prepare

Green tea is made using fresh Camellia sinensis leaves. It can offer many health benefits, like preventing several types of cancer, preventing heart disease, promoting weight loss and improving mental health. 

Green tea has so many benefits because this plant is rich in phenolic compounds, catechins, flavonoids and caffeine. These substances contain antioxidant, hypoglycemic, anti-obesity, anti-inflammatory, antibacterial, antiviral, antimutagenic, diuretic and stimulating action.

Green tea can be found in supermarkets, natural health stores or pharmacies in powder, teabag or capsule form. 

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Health benefits

The main health benefits that green tea can provide include: 

1. Preventing some types of cancer

Consuming green tea regularly helps to prevent some types of cancer, mainly prostate, colon, stomach, breast, lung, ovarian and bladder cancer. This tea is rich in antioxidants that prevent cellular damage caused by excessive free radicals. 

In addition, the high quantities of catechins found in green tea help to strengthen the immune system, which can prevent the formation of cancerous cells.

2. Promoting weight loss

Because of its diuretic effect, green tea is also effective in eliminating excess fluid in the body and reducing swelling and water retention. Learn about other teas for water retention that you can prepare at home. 

In addition, the bioactive compounds in green tea, like caffeine, catechins and flavonoids, also help to boost metabolism. This can lead to more calorie burning and stimulate weight loss.

3. Preventing early aging

Green tea has a high amount of antioxidants that treat free radicals that may cause wrinkles, flaccidity, and early aging. 

The catechins present in green tea also help to reduce advanced glycation end-products (AGEs) to reduce inflammation and prevent skin flaccidity. 

4. Preventing cold and flu

Green tea contains antimicrobial properties that help to fight bacteria and virus cells. It can prevent the emergence of viral illnesses like a cold, influenza A and influenza B. 

5. Preventing heart disease

Green tea helps to regulate cholesterol levels, mainly "bad" cholesterol or LDL. It contains high amounts of antioxidants and helps to inhibit clot formations in the blood. It is beneficial to prevent conditions like heart attacks, heart failure and thrombosis. 

6. Improving dental health

Due to its antimicrobial and anti-inflammatory properties, green tea and help prevent cavities and gum inflammation, which reduces the risk for periodontitis. This tea is also a great option for managing bad breath. 

7. Preventing diabetes

Due to the antioxidant action of catechins, green tea reduces oxidative stress and improves insulin functioning. This helps to regulate blood sugar levels to prevent or treat diabetes. 

8. Managing blood pressure

In addition to being a diuretic, green tea also contains catechins, which are bioactive compounds with antioxidant properties. They help to dilate blood vessels and, consequentially, regulate blood pressure. 

Although the caffeine in green tea is thought to increase blood pressure, studies  [1,2,3] have shown that the high amounts of catechins in this tea help to decrease inflammation, reduce oxidation and improve blood circulation to manage blood pressure. 

Green tea also contains 3 times less caffeine than coffee, therefore it is still a good option to help manage high blood pressure. 

9. Improving performance during exercise

Regularly drinking green tea can improve performance during resistance-based workouts. It can also stimulate the use of body fat for energy and increase calorie burning.  

10. Preventing neurodegenerative disease 

The catechins and flavonoids in green tea contain essential antioxidant activity that fights free radicals in the brain and prevents neurodegenerative disease, like Alzheimer’s and Parkinson’s disease. 

In addition, the polyphenols present in green tea also help to improve memory and mobility in people with Alzheimer’s and Parkinson’s.

11. Maintaining intestinal health

The catechins present in green tea contain antioxidant, antimicrobial and anti-inflammatory action that strengthens the good bacteria in the gut. These compounds also fight bad bacteria to keep the intestines healthy and treat intestinal infections and inflammatory bowel diseases. 

In addition, green tea also contains caffeine, a bioactive compound that naturally stimulates bowel movements. It can be a good option for stimulating bowel movements and managing constipation. 

12. Improving mood and concentration

Green tea contains caffeine, a substance that can boost nervous system functioning. It also promotes the release of serotonin to improve overall mood.

Green tea also increase the release of adrenaline, noradrenaline and dopamine in the body, which are hormone and neurotransmittors that boost concentration and reduce drowsiness. 

13. Treating water retention 

The main component of green tea is caffeine, which contains diuretic properties that help to manage water retention. It also contains other components in lesser quantities, like theobromine and theophylline, which help to stimulate fluid elimination and decreases symptoms of hypertension.

How to prepare

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Green tea can be prepared on its own or with lemon and mint leaves to help add flavor.


  • 1 cup of water
  • 1 teaspoon of green tea leaves
  • Juice of half a lemon 

How to prepare:

Boil the water in a pot or teapot, add the green tea leaves and remove from heat. Cover the pot and allow to infuse for for 10 minutes. Then strain, add the lemon juice and drink warm or cold.

How to take green tea

You are advised to green 2 to 4 cups of tea per day between meals. People who have high blood pressure should drink a maximum of 3 cups of green tea per day.

Green tea taken in capsule form should be taken in a 1 capsule dose, 2 to 3 times per day. 

Green tea should be consumed between meals, as it can decrease the absorption of some nutrients, like iron and calcium. 

Possible side effects

When consumed in high quantities, green tea can cause nausea, headaches, insomnia, irritability, burning, esophageal irritation, vomiting and arrhythmias. 

In addition, when excessive doses are taken, green tea can decrease the absorption of iron, and can cause liver toxicity.


Green tea is contraindicated for use during pregnancy and breastfeeding. It is not recommended for people who have difficulty sleeping, or having a history of thyroid, kidney, liver, anemia and stomach problems. 

Green tea may also interfere with the action of some medications, like anticoagulants, cholesterol meds, and blood pressure meds, therefore consumption of green tea should be monitored by a doctor.