The consumption of fermented black tea has been common in the West for thousands of years. Recently, the health effects of green unfermented tea, as consumed in the Orient, has garnered much scientific attention. Epidemiological evidence from studies in Japan showed significant cancer preventative effects from the daily consumption of green tea.
Further human and animal studies have shown a remarkable anticancer effect from the polyphenols and gallocatechins present in green tea and green tea extracts.
The results of these studies have been impressive enough for the National Cancer Institute to evaluate green tea and the polyphenols found in green tea extracts in its Designer Nutrient Program, an international research effort to investigate the cancer preventative and therapeutic benefits of green tea. Although the scope of the international research on the health effects of green tea is enormous, several conclusions have been reached.
The polyphenols and gallocatechins present in green tea have numerous impressive biological functions. These include potent antioxidant effects, which studies have shown to be twenty times stronger than vitamin E and four stronger than BHA; protection from radiation, including increased survival and decreased incidence of radiation-induced tumors; anti-mutagenic action, against both spontaneous and chemically induced mutations; anti-tumor action, inhibiting tumor cell growth, as well as preventing spontaneous and chemically induced cancer development; antibacterial activity against food-borne pathogenic bacteria and cavity-inducing bacteria; cholesterol and body-fat lowering activity in subjects on normal or high-fat, high-cholesterol diets.
Regulatory effects on blood pressure and high-blood-pressure-induced strokes were impressive, with persons consuming greater than five cups a day (or one 250 mg supplemental capsule) having a 500% decrease in stroke incidence; anti hyperglycemic action, lowering both blood glucose and normalizing insulin release; bowel regulating effects, helping both diarrhea and constipation; and antiviral effects, inhibiting reproduction of numerous viruses including influenza and human immunodeficiency virus (HIV).