Green Tea and Breast Cancer

Tea, which contains catechins and other polyphenols, has been shown to have many health benefits, including reducing risk of heart disease, stroke, and cancer. Both black tea and green tea have cancer fighting effects.

These two teas come from the same plant, but black tea has been oxidized. Oxidation occurs when the leaves are chopped, activating polyphenol oxidase, which rapidly results in black tea. Tea will remain green if tea leaves are steamed first, deactivating the enzyme and thereby preserving polyphenol content. Without oxidation, the polyphenol EGCG, or epigallocatechin-3-galate remains intact in green tea, along with other polyphenols.

EGCG has been shown to inhibit growth of ER (estrogen receptor positive) breast cancer and induce apoptosis of HER2-postive breast cancer cells in mice, even those that are resistant to Herceptin. It also has been shown to have a synergistic effect with Tamoxifen and Taxol in inhibitng the growth of ER cells. Green tea polyphenols have also been shown to inhibit development of breast cancer cells from normal breast cells, and may also prevent recurrent breast cancer (stage I and II).

Intake of mushrooms may decrease breast cancer risk, and there is also a synergistic effect with intake of green tea with mushrooms, further reducing breast cancer risk. Green tea does interact with nutrient absorption, reducing the absorption of folic acid and iron, but this may in turn reduce breast cancer risk by reducing amounts of folic acid and iron in breast tissue that can promote breast cancer.

A word of caution: drinking very hot tea is associated with increased risk of esophageal cancer and should be avoided. On the other hand, intake of ice tea and cold bottled teas has minimal beneficial effects due to the low polyphenol content, unless iced tea is made and served fresh. When brewing tea, let it steep at least three minutes to extract the greatest amount of phytochemicals.

by Julie Harris, M.S., R.D., L..D.

References: The Color Code, by James A Joseph, and


Leave a Reply