Choan, E., Roanne Segal, Derek Jonker, Shawn Malone, Neil Reaume, Libni Eapen, and Victor Gallant. “A prospective clinical trial of green tea for hormone refractory prostate cancer: an evaluation of the complementary/alternative therapy approach.” In Urologic Oncology: Seminars and Original Investigations, vol. 23, no. 2, pp. 108-113. Elsevier, 2005.
Tea culture of Korea was actively suppressed by the Japanese during the Japanese forced occupation period (1910‒1945), and the subsequent Korean War (1950‒1953) made it even harder for the Korean tea tradition to survive. The restoration of the Korean way of tea began in the 1970s, around Dasolsa. Commercial production of green tea in South Korea only began in the 1970s,. By 2012 the industry was producing 20% as much tea as Taiwan and 3.5% as much as Japan. Green tea is not as popular as coffee or other types of Korean teas in modern South Korea. The annual consumption per capita of green tea in South Korea in 2016 was 0.16 kg (0.35 lb), compared to 3.9 kg (8.6 lb) coffee. Recently however, as the coffee market reached saturation point, South Korean tea production doubled during 2010‒2014, as did tea imports during 2009-2015, despite very high tariff rate (513.6% for green tea, compared to 40% for black tea, 8% for processed/roasted coffee, and 2% for raw coffee beans).
Green tea contains significant amounts of flavonoids, antioxidants that protect against heart disease by slowing the breakdown of LDL cholesterol, preventing blood clots, and improving blood vessel function. The benefits of green tea also include associations with lower cholesterol and lower rates of artery blockages. People who drink a cup or two a day have a 46 percent lower risk of developing narrowed arteries. Upping that to three cups a day lowers the risk of having a heart attack by 43 percent and of dying from a heart attack by 70 percent. It can even help prevent a second heart attack. In a study of 1,900 patients recovering from heart attacks at Beth Israel Deaconess Medical Center in Boston, the death rate among patients who drank at least two cups of tea a day was 44 percent lower than among non-tea drinkers.
Research also shows that green tea lowers total cholesterol, improving the overall cholesterol profile. One population-based clinical study found that men who drink green tea are more likely to have lower total cholesterol than those who do not drink green tea. Other clinical studies that look at populations of people indicate that the antioxidant properties of green tea may help prevent atherosclerosis, particularly coronary artery disease. The benefits also seem to extend to preventing stroke, reducing high blood pressure, and inhibiting the formation of blood clots. Much of the effect may also be due to the ability of green tea to help lower blood sugar and insulin levels.
Grown under shade for three weeks prior to plucking, gyokuro is one of the most exclusive varieties of tea produced in Japan. The shading technique imparts a sweeter flavor, and produces a particularly rich color thanks to the higher amounts of chlorophyll in the shaded leaf. Gyokuro tea is associated with the Uji region, the first tea-growing region in Japan. It is often made using smaller-leaf cultivars of the tea plant.