TEA AND CANCER
In a study carried out in Japan over a ten-year period, consumption of 3 or more cups of green tea a day was shown to reduce the risk of recurrence of breast cancer (Cancer Lett. 2001, 167,175-82).
In Japan, The Saitama Cancer Research Institute has discovered that women with a history of breast cancer who drank 5 cups of tea daily were 50% less likely to have a recurrence than women who drink none or less than 5 daily cups. In a separate study, drinking strong tannin-rich tea has been shown to benefit genetic haemochromatosis, since tannates and other ligands inhibit the absorption of iron (BMJ no. 7168 (7th Nov ’98) p1330).
A Chinese study has shown that men who drink at least 1 cup of green tea per week for 6 months have a reduced risk of cancer of the colon, rectum or pancreas (Int. J. Cancer 1997, 70, 255-258).
A joint US-Chinese study carried out in China compared green tea consumption among 133 stomach cancer patients, 166 patients with colonic gastritis and 433 people with no stomach disease. They found that people who drank one to three cups of green tea daily had a 30% lower rate of stomach cancer, whilst those who drank more than three cups had a 61% lower rate (International Journal of Cancer, May 2001).
In research at the Karolinska Institute in Stockholm, finding suggests that a compound found in green tea may be useful in fighting malignant tumors, which must form new blood vessels in order to grow. Drs. Yihai Cao and Renhai Cao report that green tea, and one of its components, epigallocatechin-3-gallate (EGCG), significantly prevents the growth of new blood vessels in animals. The researchers conclude that long-term consumption of 2 to 3 cups of green tea might inhibit angiogenesis, an effect that may be beneficial in the prevention of cancers as well as other angiogenesis-dependent diseases, such as diabetic retinopathy - an eye disease that is a common cause of blindness. The researchers warn that where angiogenesis is important, as in pregnancy or in patients with healing wounds, people should not drink large amounts of tea. (Nature 1999;398:381-382).
Previous studies have shown that green tea contains powerful anti-oxidants that fight harmful free radicals. This enables green tea to reduce the risk and prevent the development of many cancers. But the effect of green tea is not limited to internal organs. It can also improve the health of the skin by preventing wrinkles, reducing damage from sunburn and even decreasing the risk of skin cancer when applied topically. A recent study reviewed several previous studies that looked at green tea and skin. Green tea taken orally or applied directly to the skin has prevented damage from ultraviolet light, which can lead to skin cancer. Mice exposed to a chemical that causes skin cancer were less likely to develop tumours if they had green tea ointment applied for 1 week prior to exposure. (Archives of Dermatology 2000;136:989-994, 1051).
In an Australian study of 254 Chinese patients with epithelial ovarian cancer and 652 healthy controls, it was found that the risk of ovarian cancer declined both with the more tea they drank and the length of time they had been drinking tea, with those drinking tea daily having only 39% of the risk (compared to non tea drinkers) and those who had drunk tea for more than 30 years having a 23% risk. (Cancer Epidemio Biomarkers Prev 2002; 11: 713-18).
