Natural Health Products

Green Tea

Common Name(s): Green Tea
Scientific Name(s): Camellia sinensis L. (Family: Theaceae); synonym: Thea sinensis, Camellia thea, Camellia theifera, Thea bohea, Thea viridis
Green Tea
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General Information

Green tea is made from an evergreen shrub called Camellia sinensis, native to China, Japan, and countries in North Africa and Middle East.

How to Use

People commonly consume green tea as a beverage or as an extract. When taken by adults, it is recommended not to exceed 690 mg of total catechins and 150 mg of caffeine per day.

Your health care provider may have recommended using this product in other ways. Contact a health care provider if you have questions.

What to Use For

Green tea extract is used as a source of antioxidants for the maintenance of good health. It is also used as an adjunct to a weight management program in combination with healthy diet and regular exercise.

It may be used to lower the risk of heart disease, cholesterol levels, and certain types of cancer.

Your health care provider may have recommended this product for other conditions. Contact a health care provider if you have questions.

Be Aware Of

There may be some evidence to support the use of green tea extract in lowering the risk of heart disease, cholesterol levels, and certain types of cancer. There is limited evidence to support the use of green tea extract for other conditions.

When consumed in moderate amounts, green tea is usually well tolerated. Side effects may include bloating, constipation, diarrhea, gas, nausea, and upset stomach. In rare cases, it may cause liver damage, lowered potassium levels, and a rare type of blood clotting condition called thrombotic thrombocytopenic purpura.

Green tea extract may interact with:

  • 5-fluorouracil
  • adenosine
  • anticoagulants (e.g., apixaban, warfarin)
  • antiplatelets (e.g., acetylsalicylic acid (ASA), clopidogrel)
  • atorvastatin
  • beta agonists (e.g., salbutamol, vilanterol)
  • bortezomib
  • cimetidine
  • clozapine
  • dipyridamole
  • diuretics (e.g., furosemide, hydrochlorothiazide)
  • ephedrine
  • estrogens
  • ethosuximide
  • fluvoxamine
  • imatinib
  • lisinopril
  • lithium
  • monoamine oxidase inhibitors (e.g., phenelzine, rasagiline, selegiline)
  • nadolol
  • nicotine
  • quinolone antibiotics (e.g., ciprofloxacin, moxifloxacin)
  • rosuvastatin
  • seizure medications (e.g., carbamazepine, phenobarbital, phenytoin, valproate)
  • stimulants (e.g., amphetamines, lisdexamfetamine)
  • theophylline
  • verapamil

Consult a health care practitioner before using green tea extract if you:

  • are pregnant or breast-feeding
  • are experiencing diarrhea
  • have any of the following medical conditions:
    • anxiety
    • bleeding disorders
    • diabetes
    • glaucoma
    • heart conditions
    • high blood pressure
    • irritable bowel syndrome (IBS)
    • liver disorder or symptoms of liver trouble
    • iron deficiency
    • osteoporosis due to menopause

Before taking any new medications, including natural health products, speak to your physician, pharmacist, or other health care provider. Tell your health care provider about any natural health products you may be taking.

Reference

  1. Health Canada. Drugs and Health Products. Green Tea Extract. https://webprod.hc-sc.gc.ca/nhpid-bdipsn/atReq.do?atid=greentea_thevert&lang=eng.
  2. Natural Medicines Comprehensive Database. Green Tea. 

All material copyright MediResource Inc. 1996 – 2020. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.