The health effects of green tea have long been touted by the Chinese people, but within the past few decades, green tea has received more attention in the United States. Because green tea is rich in catechin polyphenols, particularly epigallocatechin gallate (EGCG), it is a powerful anti-oxidant. Drinking green tea is reputed to be helpful in preventing cancer, rheumatoid arthritis, high cholesterol, cardiovascular disease, infection, and impaired immune function.
What makes green tea different from other Chinese teas?
Green, oolong, and black teas all come from the leaves of the Camelia sinensis plant. However, green tea leaves are steamed, which prevents the EGCG from being oxidized. Black and oolong tea leaves are made from fermented leaves, which results in the EGCG being converted into other compounds that are not nearly as effective in preventing and fighting various diseases.
Health Benefits of Green Tea
Green Tea Fights Against Cancer
Most scientists believe that catechins in green tea have a tremendous effect on cancer. It is believed that it lowers the toxicity of certain carcinogens, thereby reducing their cancer-reducing potential. It also interferes with the binding of cancer-causing substances to the DNA of healthy cells. Green tea also acts as an antioxidant, protecting your body from free radical damage. Furthermore, scientists believe that green tea works together with antioxidants and enzymes in the small intestine, liver, and lungs to prevent tumors from starting. Thus, it inhibits tumor activation.
Interest in green tea and its effect on cancer was initially aroused by a comparison of the lung cancer rates in Japan to those of the United States. The Japanese seemed to smoke nearly twice as many cigarettes as Americans, but had only about half the amount of lung cancer. So far, green tea has been studied as having a positive influence on stomach, pancreatic, colon, esophageal and prostate cancers. With stomach cancer, a case-controlled study in Northern Kyushu, Japan, found that people who drank 10 or more cups of green tea per day had a decreased risk of gastric cancer. With pancreatic cancer, a study found that those who drank 2 or more cups of green tea per day, the risk of developing pancreatic cancer was almost 60% lower than those who did not drink tea. With colon cancer, a 1990 study published in the Japanese Journal of Cancer Research found that consumption of green tea lowered the risk of colon cancer. In 1994 the Journal of the National Cancer Institute published the results of an epidemiological study indicating that drinking green tea reduced the risk of esophageal cancer in Chinese men and women by nearly sixty percent. And finally, in a recent study by the University of Purdue, prostate cancer cells were mixed with testosterone, the hormone that makes them grow uncontrollably. But when green tea extract was added to the solution, the cells grew more slowly. The more green tea, the slower the growth of the cancer cells.
Green Tea Helps Stabilize Diabetes
Insulin, a hormone produced by the pancreas, is made in response to the level of glucose (sugar) in the bloodstream. Insulin serves two purposes: it lowers blood sugar levels and increases the availability of sugar for normal cell functioning. Normally, after a meal, complex carbohydrates are digested and absorbed from the intestine into the bloodstream in the form of glucose and other simple sugars. This resulting rise in blood sugar causes the pancreas to secrete insulin, which encourages the transportation of sugar from the blood into the cells. As blood sugar levels fall, blood insulin levels return to the pre-meal state.
With diabetes, either the pancreas secretes too little or no insulin in response to the rise in blood sugar after a meal or the pancreas secretes a normal amount of insulin but the cells do not respond to the hormone. In either case, the result is that blood sugar levels remain high, and many complications can develop in the body from the abnormal blood sugar levels.
One study found that feeding green tea to rats reduced both blood glucose and insulin levels, and that catechins were very effective starch and sucrose blockers in the digestive tracts of rats. Similar results were observed in humans. When 300 mg (about 3 cups) of green tea were given to subjects ten minutes before taking in 50 grams of starch, their glucose and insulin levels did not rise nearly as much as was expected. Besides, because of green tea’s starch-blocking effect, it may also help get rid of excess fat, the villain that can make diabetes much worse.
Green Tea Prevents Cardiovascular Disease
Drinking green tea is said to improve cholesterol levels, thereby reducing platelet aggregation, and helping keep blood pressure in check. There is research indicating that drinking green tea lowers total cholesterol levels, as well as improving the ratio of good (HDL) cholesterol to bad (LDL) cholesterol. Green tea also inhibits the abnormal formation of blood clots. This is important when you consider that thrombosis (the formation of abnormal blood clots) is the leading cause of heart attacks and stroke. Much of these affects can be contributed to green tea’s antioxidants that decrease the effects of free radicals from a fatty diet that contribute to blood clot formation and atherosclerosis.
If you remember in the 1990’s researchers studied the “French Paradox” where the French people consumed a higher fat diet than the Americans but had a lower incidence of heart disease. The answer was the French drank more red wine which contains resveratrol. In a 1997 study, researchers from the University of Kansas determined that EGCG found in green tea is twice as powerful as resveratrol.
If you find this post interesting, please return here tomorrow for part two of this post which will include the treatment of acne, weight loss, tooth decay, and how much green tea you should drink to get its benefits.