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Tea has a long and varied history that includes everything from it being used for social occasions, to religious ceremonies, to political rebellion. In fact, next to water, it is the most widely consumed beverage in the world.
Derived from a plant native to Central and Eastern Asia, tea can be classified into four different basic types: black, green, oolong and herbal. These types are determined both by the process used to prepare the leaves and by the amount of oxidation the leaves receive.
Black teas — which comprise about 90 percent of tea consumption in this country — have leaves that have been withered, rolled, sifted and fermented. Green tea leaves are fired soon after they are harvested to prevent fermentation, yielding a distinctive green-gold color and a more delicate taste than the amber-colored black tea leaves. Oolong tea leaves are withered, rolled, twisted and partly fermented, producing a taste and appearance that is in between that of black and green teas. Instead of leaves, herbal teas contain grasses, peels, leaves, berries, flowers and flavorings derived from a variety of plants.
For centuries, many cultures have recognized tea for its medicinal purposes. New studies are confirming many of these traditional uses of tea for healing and health. Green tea in particular has been shown to have some amazing health benefits. Here are some of the highlights:
All plants contain certain phytochemicals (both polyphenols and carotenoids) that help them fight disease. Tea—particularly green tea—is rich in particular types of polyphenols called catechins that are particularly powerful. Studies have shown the significance of a polyphenol called epigallocatechin-3-gallate (EGCG) found in green tea.
EGCG has antioxidant effects against unstable molecules, or free radicals, which can damage healthy cells in the body. According to the American Cancer Society, EGCG may help kill types of cancer cells. One study, for example, found EGCG worked to suppress lung cancer cells, and an analysis of several studies indicated that women who drank green tea regularly had a lower risk of developing breast cancer than non-green tea drinkers.
Another study, this one by the University of California Los Angeles, found that men who had been diagnosed with prostate cancer who drank green tea had less inflammation of prostate tissue than those study participants who did not drink green tea.
Heart Diseases and High Blood Pressure Protection
In Japan, where green tea is consumed on a wide basis, a study of more than 40,000 people found that green tea drinkers had a significantly lower risk of dying from cardiovascular disease or stroke than people who did not drink green tea. Those catechins contained in green tea inhibit the free radicals in the lining of the arteries, which helps to prevent blood clots. A study published in the Journal of the American College of Nutrition concluded that consuming green tea with 200–300 mg of EGCG is useful for “maintaining cardiovascular and metabolic health.”
Research also has linked drinking green tea with reductions in LDL or “bad” cholesterol. A study published in the Journal of the American Dietetic Association showed that green tea catechins taken in capsule form or in beverage form led to statistically significant reductions in total and LDL (“bad”) cholesterol compared to a control study group who did not consume any green tea.
Many dieters have found that green tea works as part of a healthy eating and exercise regime. The polyphenol in green tea works to heighten levels of fat oxidation and the rate at which your body turns food into calories. In one British study, participants who drank four cups of tea each day had a 12 percent higher fat oxidation rate and burned an average of 67 additional calories a day than those who drank no green tea.
Green tea may help to regulate glucose levels in the body, helping to prevent spikes in insulin. An analysis of nine studies with a combined total of 324,141 participants revealed that drinking more than four cups of green tea daily may contribute to reduced risk of type 2 diabetes.
Brain imaging taken as part of a Swiss study showed that participants who drank green tea had greater activity in the area of the brain that involves working memory, and that their green tea consumption have worked to stop the plaque formations that are connected with Alzheimer’s disease.
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Green tea may also help you relax. It contains theanine, an amino acid that provides a calming effect.
Most studies are based on drinking five or more cups of green tea a day, but a few show results with just two to three cups a day. Since most current studies focus on the health benefits of green tea, you may be wondering about the benefits of other teas. All teas contain EGCG, but since green tea leaves are steamed, they retain higher concentrations of the compound.
Temperature and brewing time do affect the EGCG content and antioxidant potential of green tea. Boiling water can kill the useful catechins, so aim for water temperature of 160 to 170 degrees. The health benefits will degrade as the tea cools, however, so drink freshly brewed tea.
Also be sure to steep the tea for a minimum period of three to five minutes. Skip the milk, as dairy products make it harder for your body to absorb the catechins. Instead add some lemon; vitamin C aids in the absorption process.
Yes, green tea does contain caffeine – even caffeine-free kinds have some caffeine — so be mindful of other sources of this stimulant in your diet. Green tea does contain less caffeine than coffee. A six to eight ounce cup of green tea contains about 30 to 60 mg. of caffeine as compared with about 100 mg. in eight ounces of coffee. Nevertheless, if you regularly take medications or supplements, it’s a good idea talk with your doctor before adding multiple cups of green tea to your diet.
Green tea also contains tannins, which can decrease the body’s absorption of iron and folic acid. Green tea consumption is not ideal for pregnant women or those trying to conceive, since those nutrients are important for both baby and mother.
Keep in mind that canned or bottled green tea drinks have little of the tea’s health benefits. As with other foods, canning and other processes deplete the nutrient content. So brew yourself a cup of fresh tea and try this powerhouse beverage for yourself.