Green Tea
Introduction
This fact sheet provides an overview of green tea, including its common names, uses, potential side effects, and resources for further information.
Common Names
- Green tea
- Chinese tea
- Japanese tea
Latin Name
- Camellia sinensis
Uses
Green tea and its extracts, particularly EGCG, are used for:
- Preventing and treating various cancers (e.g., breast, stomach, skin)
- Improving mental alertness
- Aiding in weight loss
- Lowering cholesterol levels
- Protecting skin from sun damage
How It Is Used
Green tea is typically brewed and consumed as a beverage. Extracts can be taken in capsule form and are sometimes included in skin care products.
Scientific Insights
- Laboratory studies indicate that green tea may help protect against or slow the growth of certain cancers, though human studies have shown mixed results.
- Some evidence suggests that green tea can enhance mental alertness, likely due to its caffeine content. However, there is insufficient data to confirm its effectiveness in weight loss, cholesterol reduction, or skin protection.
- Ongoing studies are being supported by NCCAM to explore the effects of green tea components on conditions like cancer, diabetes, and heart disease.
Side Effects and Cautions
- Generally safe for most adults in moderate amounts.
- Rare cases of liver issues have been reported with concentrated extracts, not with brewed tea. It is advised to take extracts with food and consult a healthcare provider if liver problems arise.
- Contains caffeine, which may cause insomnia, anxiety, irritability, upset stomach, nausea, diarrhea, or frequent urination in some individuals.
- Contains small amounts of vitamin K, which may interfere with anticoagulant medications like warfarin.
- It is important to inform healthcare providers about any complementary practices to ensure coordinated care.
Sources
- Sarma DN, Barrett ML, Chavez ML, et al. Safety of green tea extracts: a systematic review by the US Pharmacopeia. Drug Safety. 2008;31(6):469-484.
- National Cancer Institute. Tea and Cancer Prevention.
- Green tea. Natural Medicines Comprehensive Database.
- Green tea (Camellia sinensis). Natural Standard Database.
NCCAM National Institutes of Health
This summary provides a comprehensive look at green tea, its benefits, and considerations for use.
