What is green tea?

All types of tea are made from the camellia sinensis plant. Green tea gets its name from the emerald green colour created when brewing these unprocessed, unfermented leaves.


With origins dating as far back as 5,000 years, green tea is commonly drunk and grown in East Asia where the health properties are highly valued.

Green tea benefits include:

  • High in protective plant compounds called polyphenols
  • May support focus and attention
  • May promote calm
  • May protect the brain
  • May boost metabolism
  • May support blood sugar control
  • May reduce diabetes risk
  • May reduce the risk of heart disease
  • May support bone health
  • May improve gut health

Discover our full range of health benefit guides and read more about the profile of other teas in our series: including ginger tea, peppermint tea, chamomile tea and rooibos tea.

Nutritional profile of green tea

The drink’s primary nutritional benefits lie in the active plant compounds it contains. These include epicatechin, gallic acid and epigallocatechin.

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The tea you use, the temperature and the steeping time all have a significant effect on the levels of these compounds. Warm and ambient temperatures are best to retain antioxidant compounds, so allow the boiled water to cool slightly before pouring over the tea leaves, and steep for between 2-3 minutes.

A woman drinking tea feeling relaxed

What are the top 10 health benefits of green tea?

1. High in protective plant compounds called polyphenols

Compounds called polyphenols are known to protect the body against disease and make an important contribution towards a healthy, balanced diet. These antioxidant compounds are found in a wide range of fruit, vegetables and other unprocessed foods.

Green tea has numerous health benefits many of which are attributed to the fact that it is largely unprocessed and rich in these plant compounds. The main bioactive compounds in green tea are flavonoids, with the most potent being catechins and epigallocatechin gallate (EGCG).

2. May support focus and attention

Green tea contains a number of natural stimulants, including caffeine, which although not at the same levels as that found in coffee, may still help maintain alertness and focus.

3. May promote calm

Green tea is a source of the amino acid L-theanine, which has a relaxing effect; it does this by increasing mood-enhancing brain chemicals including GABA, dopamine and serotonin.

4. May protect the brain

The beneficial polyphenols of green tea may help slow the damaging effects of aging on the brain.

5. May boost metabolism

Research suggests that green tea may exert a small weight loss in overweight or obese people. This is thought to be thanks to the natural thermogenic properties provided by caffeine, and by the plant compounds such as catechins.

6. May support blood sugar control

Studies suggest green tea may improve insulin sensitivity and as a result have a beneficial effect on blood sugar management.

7. May reduce diabetes risk

Tea polyphenols have the ability to inhibit digestive enzymes like lactase and delay the uptake of glucose (sugar) in the gut, this has led some studies to conclude that a consistent intake (over a lifetime) of polyphenols from the likes of green tea may be as effective as some medication in reducing the risk of diabetes; however, more studies are needed.

8. May reduce the risk of heart disease

Research suggests green tea is a useful beverage for helping to reduce the risk of heart disease and associated conditions, such as stroke. One way it may help is in its beneficial effects on cholesterol management.

9. May support bone health

Green tea may help maintain bone density and as a result reduce the risk of fracture. The protective effect is thought to be thanks to the tea’s polyphenol content.

10. May improve gut health

Plant compounds like polyphenols, including those from tea, pass unabsorbed to the large intestine where they are broken down by gut bacteria. In this way they provide a source of fuel for the beneficial bacteria that reside in this part of the gut, allowing them to thrive and diversify and helping to improve gut function and modify the immune system.

A woman making a heart shape with her hands over her stomach

Is green tea safe for everyone?

If you’ve been diagnosed with iron-deficiency anaemia you should be aware that, like other teas, green tea contains natural compounds called tannins. These compounds interfere with the absorption of iron – for this reason it’s useful to avoid drinking tea with an iron-rich meal and leave at least one hour before having a brew.

Because of green tea’s beneficial effects, a number of ‘health’ products include traces of green tea. However, there is limited evidence to suggest these products are effective. If you are hoping to use green tea for medicinal purposes, refer to your GP to ensure you may do so without risk to your health.

If you are sensitive to caffeine, it is advisable to limit the total number of caffeinated drinks you drink in a day. Too much caffeine may disrupt sleep and, in some people, increase anxiety; if this is relevant to you, look to reduce your intake and aim to have your last caffeinated drink at about 12 noon.

Overall, is green tea healthy?

Green tea offers numerous health benefits – it’s a relaxing drink that helps increase our attention and focus, is heart-friendly, good for the gut and may help manage blood sugar. It offers a useful option if you are looking for a flavourful, low-calorie, unsweetened hot drink with less caffeine than coffee.

Looking for more information on how much caffeine is in tea? Our in-depth guide compares different types of tea and discusses which factors affect the caffeine content.

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This article was reviewed on 20 February 2024 by Kerry Torrens.

Jo Lewin is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Follow her on Twitter @nutri_jo.

Kerry Torrens BSc. (Hons) PgCert MBANT is a Registered Nutritionist with a post graduate diploma in Personalised Nutrition & Nutritional Therapy. She is a member of the British Association for Nutrition and Lifestyle Medicine (BANT) and a member of the Guild of Food Writers. Over the last 15 years she has been a contributing author to a number of nutritional and cookery publications including Good Food. Find her on Instagram at @kerry_torrens_nutrition_


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