Updated 05 October 2015

All about green tea

Green tea is 25 times better than vitamin E at shielding cells from damage that causes cancer and heart disease. Learn more.


Key benefits of green tea

  • Research indicates that green tea may benefit people who have arthritis by reducing inflammation and slowing cartilage breakdown.
  • The high antioxidant (polyphenol) content of green tea has lead researchers to believe that the tea could possibly reduce cancer. Japanese research shows, for example, that drinking green tea may lower your risk of developing certain blood cancers. Other research shows that green tea may help prevent oral cancer. But overall, the relationship of green tea consumption and cancer remains inconclusive.
  • Research seems to indicate that regular intake of green tea may cut one's risk for atherosclerosis, and thus also the risk of heart attack.
  • There's strong evidence to suggest that green tea helps to prevent cold and flu symptoms.
  • One study showed that a fertility blend that contained green tea helped women to conceive.
  • Research indicates that green tea could possibly have a positive effect on cholesterol levels.
  • One study conducted in healthy postmenopausal women showed that a menopausal formula containing green tea was effective in relieving menopausal symptoms, but more research is needed to confirm these results.
  • Several small studies have looked at the use of green-tea extract capsules for weight loss and weight maintenance. Study results are mixed (although some were quite positive), and better research is needed before a strong recommendation can be made.
  • A chemical found in green tea may also shrink lymph nodes and reduce white blood cell counts in patients with chronic lymphocytic leukemia (CLL).
  • Recent studies in humans and cell cultures suggest that green tea may also benefit bone health. 

Downsides of green tea

Tea has half the amount of caffeine than coffee and far less than caffeinated cooldrinks. Nevertheless, too much green tea can still hold risks. Take note that caffeine can cause:

  • Insomnia
  • Worsening incontinence, due to caffeine's diuretic effect
  • Worsening of stomach-ulcer symptoms
  • Increased heart rate and blood pressure
  • Increased blood-sugar levels

Note, however, that out of the three main types of tea, green tea contains the least caffeine. Extensive research shows that up to 300mg of caffeine (about eight cups of tea) per day isn't a health risk.

Anaemics should avoid excessive tea drinking during meals because the tannins in the tea could reduce your ability to absorb iron.

Drinking a lot of tea can discolour your teeth. But if you visit an oral hygienist every three months, this shouldn't be a problem.

How much green tea do you need?

The benefits of specific doses of green tea haven't been established.

Most studies have examined green tea in the form of a brewed beverage, rather than in capsule form. According to the US National Institutes of Health, one cup of tea contains approximately 50mg of caffeine and 80mg to 100mg of polyphenol content, depending on the strength of the tea and the size of the cup. Studies have examined the effects of habitually drinking anywhere from one to ten cups of tea per day.

In capsule form, there is considerable variation in the amount of green-tea extract, and there may be anywhere from 100mg to 750mg per capsule. Currently, there's no established recommended dose for green-tea-extract capsules.

Interesting facts

Green tea is made from the dried leaves of Camellia sinensis, a perennial evergreen shrub.

A product of the Far East, green tea is seen by many to be the healthiest tea on the market. This is because the antioxidant, epigalloctechin-3 gallate (or EGCG) that is lost during the fermentation process of black and oolong teas, is preserved in green tea. EGCG has been shown to kill cultured cancer cells.

The incidence of prostate cancer in China, where green tea is consumed regularly, is the lowest in the world.

Despite all its benefits, only four percent of all tea that is consumed worldwide is green tea. 


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