Green tea is one of the most ancient and popular beverages consumed by people in many countries of the world during centuries. Green tea originated in China and became the traditional drink not only in Chine but also in Asian countries. During last decade green tea became popular also in western countries – many people switch to green tea because of its healthy properties and health benefits.
Ancient medicine recommends green tea for several diseases. Numerous studies have previously suggested green tea and its extracts may provide suitable treatments for cancer, as well as other diseases. There is no conclusive scientific evidence that green tea helps to prevent or treat cancer in people but there are several observation studies which demonstrate health benefits of green tea.
Modern medicine is trying to understand the breakthrough involved identifying the process by which the substance of green tea attacks cancer cells (anticancer action).
Green tea contains different enzymes, amino acids, carbohydrates, lipids, sterols, dietary minerals and phytochemicals (polyphenols, flavanols, caffeine) – all of them have several positive influences at human body including anticancer functions. The researchers reveal the active component of green tea which disrupts the metabolism of pancreatic cancer cells (without interfering in healthy cells). The active biological agent of green tea (as anticancer) called epigallocatechin gallate (EGCG) changes the metabolism of pancreatic cancer cells by suppressing the expression of lactate dehydrogenase, a critical enzyme in cancer metabolism. It means green tea can be recommended for prevention and may be even for slowing pancreatic cancer development.
Some experts suggest that drinking green tea may lower risk of digestive system cancers in women while another found EGCG delivered intravenously directly to tumors made two-thirds of them shrink or disappear within one month.
Several scientific studies are offering an explanation for effect of green tea on reducing risk of cancer and slowing its progression.
Green tea was subject of several studies in Japan as Japan being the country where studying consumption of green tea is easiest (most population use green tea every day few times a day).
Japanese women already diagnosed with breast cancer, whose disease was still at an early stage (non-metastasized) and who consumed at least three cups of green tea a day, had 57% fewer relapses than women who drank one cup or less per day (Inoue et al., 2001).
Scientists noted that green tea changes estrogen metabolism and breast cancer risks. National Institutes of Health shows that the biochemicals in green tea change a women’s estrogen metabolism, revealing at least one of its mechanisms for reducing the risk of breast cancer.
Green tea (as anticancer product) can interfere with some chemotherapy drugs – this is why you should avoid green tea during chemotherapy treatments.
“As a rich source of phytochemicals that can interact with and regulate xenobiotic metabolizing enzymes, green tea may modify metabolism or conjugation of estrogens and may thereby impact breast cancer risk.”
Green tea benefits
Green tea consumption is becoming important during perimenopause and menopause. Scientific studies discovered that postmenopausal women who consume green tea every day had 20% less urinary estrone and 40% less urinary estradiol levels (compared with same age women who consume green tea less than one time per week). It is well known that high levels of estrogens (estradiol, estrone) are correlated with increased risks for breast cancer.
Men with prostate cancer notably benefited from the consumption of FIVE or more cups of tea a day. This reduced by 50% the risk that their prostate cancer would progress to an advanced stage (Kurahashi et al., 2007).
A compound in green tea has been found to kill mouth cancer cells while leaving healthy cells undamaged.
Epidemiological studies found limited evidence that green tea consumption may be associated with a moderately reduced risk of liver cancer in Chinese and Japanese people (Fon Sing M, Yang WS, Gao S, Gao J, Xiang YB, 2011).
In 2014 scientists discovered the evidence that green tea consumption may be associated with reduced risk of esophageal cancer in the Chinese population, decreased risk of lung cancer in women and lower risk of oral cancer in Asian people.
Several epidemiologic studies about association between green tea consumption and cancer risk have been published during last decades. Results are different – some are inconsistent and some demonstrated links between green tea consumption and reduced risks of cancers of the colon, breast, ovary, prostate and lung. The inconsistent results could be explained by differences in green tea preparation and consumption, by different methods of tea production, by different genetic variation in how people respond to green tea consumption and by different lifestyle factors (physical activity, weight status, eating habits) that may influence women’s risks of developing different types of cancer.
Disclaimer: It is strongly recommended to consult your doctor for professional advice. Above mentioned information and recommendations are just general and should be adapted to each person according to personal health indicators and status.