People who make green tea a regular part of their lifestyle may significantly reduce their risk of death from heart disease and colorectal cancer. According to scientists in Japan, consuming seven cups of green tea daily for the long-term is necessary to gain this benefit.
The benefits of green tea have been reported by the Chinese since ancient times, when it was used to treat headache, depression, and a wide variety of ailments. Scientific research has since provided evidence to support some of the traditional claims, as well as new ones. In 1994, for example, a study published in the Journal of the National Cancer Institute reported that drinking green tea reduced the risk of esophageal cancer by nearly 60 percent. A more recent study (August 2009) reported that green tea could be helpful against bladder cancer. Green tea has also been credited with lowering cholesterol and helping with weight loss.
The current study from Japan evaluated 12,251 adults ages 65 to 84. The researchers found that compared with drinking less than one cup of green tea daily, people who drank seven or more cups daily reduced their risk of dying from heart disease by 75 percent. A reduction in the risk of colorectal cancer was 31 percent when comparing people who drank seven cups versus those who drank less than three cups of green tea daily. Over the 5.2 years of follow-up, 1,224 patients died: 400 due to cancer and 405 from cardiovascular disease.
The key to the secret of green tea’s positive impact on heart disease and colorectal cancer may be the high levels of polyphenols (30 to 40 percent) found in green tea, compared with only 3 to 10 percent found in black tea. Polyphenols are chemical substances, found in plants, that have antioxidant properties. The four main polyphenols in tea leaves are epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).
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