Green Tea & Estrogen Levels

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Estrogen is a hormone that is essential for the normal sexual and reproductive development of women. It is produced by the ovaries and regulates the menstrual cycle. Low estrogen levels commonly occur during menopause and may lead to symptoms such as hot flashes, night sweats, vaginal dryness and mood swings. They may also indicate other conditions including atherosclerosis and osteoporosis. High levels of the hormone may increase the risk of serious conditions including breast cancer. Medications and supplements such as green tea may help regulate estrogen levels.

Green Tea

Green tea is made from the unfermented leaves of the Camellia sinensis plant that is native to East Asia. It is a popular beverage in many parts of the world. The leaves are a rich source of anti-oxidant polyphenols called catechins, along with vitamin C, and have also been used traditionally to treat a variety of conditions including high cholesterol, certain types of cancers, diabetes, liver diseases and inflammatory bowel disorder. The supplements are available as teas, liquid extracts and capsules. If you plan to use green tea for medicinal purpose, your doctor may help determine the appropriate dose for you based on your age and health history.

Estrogen Levels

The blood estrogen levels were 13 percent lower in women who regularly drink green tea, when compared to irregular tea drinkers, according to a study in the May 2005 issue of the journal “Carcinogenesis”; however, the authors of the study recommend more studies to understand the role of green tea in preventing high-estrogen related conditions such as breast cancer. Another study that was presented at the 2006 American Association of Cancer Research meeting revealed that in the laboratory green tea enhances the anti-estrogen effects of drugs such as tamoxifen. Tamoxifen is often prescribed to breast cancer patients. Thus, the study indicates that consuming green tea may be beneficial to breast cancer patients. Dr. Gideon Koren, author of the book “Medication Safety in Pregnancy and Breastfeeding,” also reaffirms that green tea may lower estrogen levels in postmenopausal women; however, these benefits have not been demonstrated in actual clinical cases, hence, more research may be needed before green tea replaces your existing anti-estrogen medications.

Side Effects

Green tea contains significant amounts of caffeine, and excessive consumption of the beverage or supplements may lead to side effects such as insomnia, dizziness, increased heart rate, irritability and anxiety. It may also cause vomiting and upset stomach. The University of Maryland Medical Center also warns pregnant and breastfeeding women and those with kidney disorders and stomach ulcers to avoid the drink. Green tea also interferes with certain blood-thinning, contraceptive and cancer medications.


Always talk to a doctor before using green tea for medicinal purposes. Choose a decaffeinated version if possible. Remember the production of green tea supplements in the United States is not regulated by the FDA. Hence, consult a pharmacist to find a product that has been tested for its safety and efficacy, or look for the USP logo, which is given to supplements that have been submitted for safety tests voluntarily.