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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

Uses

  • 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

Dosage

  • 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. http://www.nlm.nih.gov/medlineplus/druginfo/natural/960.html. Accessed March 30, 2011.

National Center for Complementary and Alternative Medicine. Green tea. http://nccam.nih.gov/health/greentea/. Accessed March 30, 2011.