Green tea is a "true" tea (i.e., Camellia sinensis) that has undergone minimal oxidation during processing. Green tea is popular in China, Taiwan, Hong Kong, Japan, Korea, and the Middle East. Recently it has become more widespread in the West as its virtues are being discovered. Green tea is so ubiquitous in Japan that it is more commonly known as "tea" (ocha) and even "Japanese tea" (nihoncha).
Generally, 1 teaspoon of tea per 6 ounces of water should be used. If the quality of the Green tea is unknown then it should be prepared with 180F water (not boiling) and steeped 2 to 3 minutes. However some finer qualities of tea require cooler water, and less brewing time. Your specific tea should come with instructions.
There is archeological evidence that suggests that tea has been consumed for almost 5000 years, with India and China being two of the first countries to cultivate it. Green tea has been used as traditional medicine in areas such as India, China, Japan and Thailand to help everything from controlling bleeding and helping heal wounds to regulating body temperature, blood sugar and promoting digestion.
- A 2006 study published in the September 13 issue of the Journal of the American Medical Association concluded "Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease but not with reduced mortality due to cancer." The study, conducted by the Tohoku University School of Public Policy in Japan, followed 40,530 Japanese adults, ages 40-79, with no history of stroke, coronary heart disease, or cancer at baseline beginning in 1994. The study followed all participants for up to 11 years for death from all causes and for up to 7 years for death from a specific cause. Participants who consumed 5 or more cups of tea per day had a 16 percent lower risk of all-cause mortality and a 26 percent lower risk of cardiovascular disease than participants who consumed less than one cup of tea per day. The study also states, "If green tea does protect humans against CVD or cancer, it is expected that consumption of this beverage would substantially contribute to the prolonging of life expectancy, given that CVD and cancer are the two leading causes of death worldwide."
- A study published in the February 2006 edition of the American Journal of Clinical Nutrition concluded "A higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans." In May 2006, researchers at the Yale School of Medicine weighed in on the issue with a review article that looked at more than 100 studies on the health benefits of green tea. They pointed to what they called an "Asian paradox," which refers to lower rates of heart disease and cancer in Asia despite high rates of cigarette smoking. They theorized that the 1.2 liters of green tea that is consumed by many Asians each day provides high levels of polyphenols and other antioxidants. These compounds may work in several ways to improve cardiovascular health, including preventing blood platelets from sticking together and improving cholesterol levels, said the researchers, whose study appeared in the May issue of the Journal of the American College of Surgeons. Specifically, green tea may prevent the oxidation of LDL cholesterol (the "bad" type), which, in turn, can reduce the buildup of plaque in arteries, the researchers wrote.
- A study published in the August 22, 2006 edition of Biological Psychology looked at the modification of the stress response via L-Theanine, a chemical found in green tea. It "suggested that the oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation." In a double-blind, randomized, placebo-controlled trial done by Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, 240 adults were given either theaflavin-enriched green tea extract in form of 375mg capsule daily or a placebo. After 12 weeks, patients in the tea extract group had significantly less low-density lipoprotein cholesterol (LDL-C) and total cholesterol (16.4% and 11.3% lower than baseline, than the placebo group. The author concluded that theaflavin-enriched green tea extract can be used together with other dietary approaches to reduce LDL-C.
- A study published in the January, 2005 edition of the American Journal of Clinical Nutrition concluded "Daily consumption of tea containing 690 mg catechins for 12 wk reduced body fat, which suggests that the ingestion of catechins might be useful in the prevention and improvement of lifestyle-related diseases, mainly obesity." Antioxidants in green tea may prevent and reduce the severity of rheumatoid arthritis, according to a CWRU's School of Medicine study published in the April 13 2005 issue of the Proceedings of the National Academy of Sciences. The study examined the effects of green tea polyphenols on collagen-induced arthritis in mice, which is similar to rheumatoid arthritis in humans. In each of three different study groups, the mice given the green tea polyphenols were significantly less likely to develop arthritis. Of the 18 mice that received the green tea, only eight (44 percent) developed arthritis. Among the 18 mice that did not receive the green tea, all but one (94 percent) developed arthritis. In addition, researchers noted that the eight arthritic mice that received the green tea polyphenols developed less severe forms of arthritis.
- A German study found that an extract of green tea and hot water (filtered), applied externally to the skin for 10 minutes, three times a day could help people with skin damaged from radiation therapy (after 16-22 days).
- A study published in the December 1999 American Journal of Clinical Nutrition found that "Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se. The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis, fat oxidation, or both."In lab tests, EGCG, found in green tea, was found to prevent HIV from attacking T-Cells. However, it is not known if this has any effect on humans yet.
- A study in the August, 2003 issue of a new potential application of Cellular and Molecular Life Sciences found that "a new potential application of ()-epigallocatechin-3-gallate [a component of green tea] in prevention or treatment of inflammatory processes is suggested"