Studies in laboratory animals have found that green tea polyphenols inhibit the growth of esophageal cancer cells (in line with its anti-cancer properties). Other clinical studies have found that green tea offers protection against the development of esophageal cancer, particularly among women. However, one large-scale population-based clinical study found just the opposite: drinking green tea was associated with an increased risk of esophageal cancer, and the stronger and hotter the tea, the greater the risk. It seems that if the water is very hot, it can damage the esophagus and lead to long-term adverse consequences. So just make sure the tea you drink isn’t extremely hot.
What are your thoughts on this topic? Chat with us on Twitter by mentioning @goodhealth and @CynthiaSass. Cynthia Sass is a nutritionist and registered dietitian with master’s degrees in both nutrition science and public health. Frequently seen on national TV, she’s Health’s contributing nutrition editor, and privately counsels clients in New York, Los Angeles, and long distance. Cynthia is currently the sports nutrition consultant to the New York Rangers NHL team and the New York Yankees MLB team, and is board certified as a specialist in sports dietetics. Cynthia is a three time New York Times best selling author, and her brand new book is Slim Down Now: Shed Pounds and Inches with Real Food, Real Fast. Connect with her on Facebook, Twitter and Pinterest.
There are also several harmful effects of green tea over-consumption that are possible. These include consuming tainted supplements marked as green tea extract, high caffeine consumption, consuming aluminum, and the effects of tea polyphenols on iron bioavailability. Green tea extracts should not be taken by patients suffering from renal failure, liver disease, heart conditions or major cardiovascular problems without supervision from a doctor. People sensitive to caffeine should be careful of their intake. Pregnant and breast-feeding women should drink no more than one or two cups per day, as some research shows that more caffeine than this amount may interfere with normal heart rhythms.
A 2007 study concluded that green tea could hold promise as a new treatment for skin disorders such as psoriasis and dandruff. Researchers studied an animal model for inflammatory skin diseases, often characterized by patches of dry, red, flaky skin caused by the inflammation and overproduction of skin cells. Those treated with green tea showed slower growth of skin cells and the presence of a gene that regulates the cells' life cycles.
Zen Buddhism and the Chinese methods of preparing powdered tea were brought to Japan in 1191 by the monk Eisai. In Japan it became an important item at Zen monasteries and from the fourteenth through to the sixteenth centuries was highly appreciated by members of the upper echelons of society. Although powdered tea has not been popular in China for some time, there is now a global resurgence in the consumption of Matcha tea, including in China.
Matcha, the focal point of the Japanese Tea Ceremony, is a fine powder made by grinding green tea leaves. Only the finest, young, shade-grown gyokuro tea leaves are used to create matcha. The leaves are plucked and laid out flat to dry. Veins are removed and the leaves, now called tencha, are carefully ground in granite mills until they become the precious powder. Easy preparation is achieved by placing 1 teaspoon of matcha per cup (or to taste) in a cup, adding a few drops of hot water (160-180F) and stirring with a spoon until a paste forms. Add the rest of the water and stir.
Japanese researchers published a study on green tea and its effect on the beta-amyloid protein plaques found in Alzheimer’s disease in the April 2008 issue of the Journal of Nutritional Biochemistry. The protein plaques associated with Alzheimer’s disease increase brain cell damage and death due to oxidative stress. The researchers found that green tea catechins reduced the level of damaging free radicals in the brains of rats. The green tea rodents showed much less plaque-induced deficits in memory compared to rodents that didn’t receive green tea and those that were infused with beta-amyloid proteins. (8)
Tea seeds were first brought to Japan in the early 9th century by the Buddhist monks Saicho and Kukai. During the Heian period (794–1185), Emperor Saga introduced the practice of drinking tea to the imperial family. The Zen Buddhist priest Eisai (1141–1215), founder of the Rinzai school of Buddhism, brought tea seeds from China to plant in various places in Japan. Eisai advocated that all people, not just Buddhist monks and the elite, drink tea for its health benefits.
Being a green tea, matcha does contain caffeine and in higher levels than other green teas. Because the entire leaf is used, matcha tea can contain nearly as much caffeine as a cup of coffee. However, caffeine release is believed to be slower because you are drinking the entire leaf. This slower release of caffeine reduces “caffeine jitters” that coffee or other teas can cause.
The next morning, I had a bagel and one daily tea, as instructed. I felt my stomach become uneasy as most stomachs do when they’re working their “digestive magic.” Suddenly, the worst cramp of my life hit me out of nowhere. It was the sharpest PANG I’ve ever felt as it made its way from my stomach to my chest. As a reflex, I jumped up. That’s when I felt another wave of pain and swiftly made my way to the restroom.
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.