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Green Tea

By

Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Last full review/revision Jul 2020| Content last modified Jul 2020
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Green tea is made from the dried leaves of the same plant as traditional tea. However, traditional tea leaves are fermented, and green tea leaves are steamed but unfermented. Green tea may be brewed and drunk or ingested in tablet or capsule form. It is thought to have effects that protect cells from damage by oxygen, mutations, and cancer. Green tea contains caffeine, but many extracts have been decaffeinated. It is high in flavonoids, polyphenols, and catechins.

Medicinal claims

Green tea is said to have multiple health benefits, few of which are supported by strong scientific evidence. People take green tea for many reasons, including prevention of cancer and coronary artery disease Overview of Coronary Artery Disease (CAD) Coronary artery disease is a condition in which the blood supply to the heart muscle is partially or completely blocked. The heart muscle needs a constant supply of oxygen-rich blood. The coronary... read more Overview of Coronary Artery Disease (CAD) , as well as treatment of external genital warts Human Papillomavirus (HPV) Infection Human papillomavirus (HPV) causes warts. Some types of HPV cause skin warts, and other types cause genital warts (growths in or around the vagina, penis, or rectum). Infection with some HPV... read more Human Papillomavirus (HPV) Infection . Other reasons are reduction of fat (lipid) levels in the blood, relief of osteoarthritis pain and menopausal symptoms, and enhancement of weight loss, memory, and longevity.

Possible side effects

Side effects are related to the effects of caffeine. They include insomnia, anxiety, rapid heart rate (tachycardia), and mild tremor. Pregnant women should avoid excessive caffeine. Rare case reports document liver toxicity.

Drug interactions

Vitamin K in green tea may decrease anticoagulant effects of warfarin, thus increasing the risk of blood clots.

More Information about Green Tea

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
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