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Green Tea (Camellia sinensis)

July 25, 2017   /

Alternate names

  • Chinese tea
  • Japanese tea

Native to

  • India
  • China

Medicinal parts used

  • Fresh leaves from the Camellia sinensis plant are steamed to produce green tea
  • Green tea is usually brewed and drunk
  • Green tea extracts are taken in capsules and are sometimes used in skin products


  • Green tea and its extracts may help protect against or slow the growth of certain cancers, but studies have shown mixed results
  • Green tea is used for improving mental alertness, aiding in weight loss, and lowering cholesterol levels, but clinical studies have not yet supported this
  • Ointment made with green tea extract has US Food and Drug Administration (FDA) approval to treat genital warts

How it works

  • Green tea extract is bioflavonoid rich, and one of its main uses is fighting free radicals in the body
  • Green tea extract contains high level of polyphenols, which may:
    • Protect against digestive and respiratory infections
    • Block the actions of carcinogens, which promote cancer
    • Help in lowering cholesterol levels

Side effects and warnings

  • Little to no side effects or contraindications in adults, when used in moderate amounts
  • Green tea and extracts contain caffeine, which can cause the following in some people:
    • Insomnia
    • Anxiety
    • Irritability
    • Upset stomach
    • Nausea
    • Diarrhea
    • Frequent urination
  • Patients on anticoagulants should use with caution because of the vitamin K content of green tea
  • If taken with stimulant drugs, green tea could increase heart rate and blood pressure


  • 3 cups tea/day provide 240–320 milligrams (mg) of polyphenols
  • 10 cups of tea daily are associated with decreased cholesterol levels

References and recommended readings

MedlinePlus. Green tea. Accessed March 30, 2011.

National Center for Complementary and Alternative Medicine. Green tea. Accessed March 30, 2011.