Incredibly, cancer, obesity, heart disease, osteoporosis, and even infections may all be partially alleviated by the same simple cure: green tea. Water brewed with Camellia Sinesis, a concoction more commonly known as tea, has played an integral role in human culture for thousands of years. Recently, a number of studies have indicated that this plant may be responsible for much more than simply quenching our thirst. As science catches up with folklore, green tea, which differs from black tea in that the leaves are not fermented, has been found to be beneficial in fighting a wide variety of human diseases.
The Camellia Sinesis plant has a large number of polyphenols, which are known to have a multitude of beneficial effects. Unfortunately, these positive attributes are destroyed during the fermentation of black tea, but remain available to green tea drinkers. In general, polyphenols are a class of molecules found in many plants, wine, and grapes, and are responsible for the bright pigmentation of a multitude of fruits and vegetables. Their primary function is to protect the plants from disease and damage from UV light. The
predominant family of polyphenols in Camellia Sinesis is the catechins. In turn, the most populous members of the catechin family are epigallocatechin gallate (EGCG), epicatechin (EC), and epigallocatechin (EGC).
Just as the polyphenols function to protect plants from UV damage, several studies have indicated that green tea catechins such as EGCG may function to prevent cancer in mammals. These polyphenols have been found to capture and remove reactive oxygen species, which are known instigators of DNA damage (and thus cancer). In humans, temporary increases in such anti-oxidant activity have been observed after the consumption of tea and green tea catechins. Scientists have cited these beneficial effects in fighting bladder, prostate, esophagus, and stomach cancer, among others. In addition to acting to prevent cancer, an April 2003 study by Dr. Hadi and colleagues suggests that in the presences of copper, these same polyphenols may also have the capacity to destroy cancerous cells through activation of oxidant pathways. Perhaps most notably, another team directed by Dr. Katiyar of the University of Alabama found that topical application of EGCG in water-resistant ointment prevented UVB-induced cell stress signals that can initiate the path to cancer. This result was duplicated even when the EGCG was administered orally in drinking water, although the effects were reduced.
In addition to possessing potential cancer-fighting properties, green tea is also attributed with the ability to fight obesity. A 1999 study published in the American Journal of Clinical Nutrition investigated whether catechin polyphenols could increase twenty-four hour energy expenditure and fat oxidation in humans. The authors, led by Dr. Vandermander, found that 90 mg of EGCG significantly increased twenty-four hour energy expenditure, and that this effect was independent of the presence of caffeine. Moreover, other studies have indicated that administering a diet high in green tea powder had suppressive effects on body weight increase, cholesterol levels, lipid metabolism and adipose tissues of mice.
These same polyphenols have also been determined to decrease the risk of atherosclerosis and heart disease. Catechins act to block the synthesis of LDL cholesterol by interfering with a key oxidation step in the normal LDL creation process. Thus, by lowering the plasma levels of LDL cholesterol, a major risk factor for atherosclerosis and heart disease, green tea yields yet another health benefit. Furthermore, some studies have indicated that green tea may also function to decrease triglyceride levels, which would help alleviate yet another risk factor for heart disease.
As if benefits in fighting cancer, obesity and heart disease weren’t enough, evidence has also highlighted a potential role for EGCG in alleviating osteoporosis. In individuals suffering osteoporosis, osteoclasts, which are cells that act to break done bone mass, proliferate and have long-term detrimental effects on the maintenance of healthy bones. For healthy individuals, the actions of these osteoclasts are balanced by those of osteoblasts, which are the primary bone-forming cells of the body. A 2002 study by Dr. Nakagawa and associates determined that EGCG induced the cell death of osteoclast-like cells after a twenty-four hour treatment. Thus, EGCG functions to reduce the cells causing the destruction of bone mass. Critically, EGCG was found to have no effect on the function or survival of the osteoblasts. Although further studies are needed to confirm these results, such research indicates yet another potentially promising benefit of green tea.
Although there are a multitude of benefits ascribed only to green tea, scientists from Brigham and Women’s Hospital and Harvard Medical School have recently identified a component present in all tea varieties that helps boost the body’s immunity. The group, lead by Dr. Jack Bukowski, isolated a molecule called L-theanine from black tea, but noted that it is also found in green and oolong tea. Their work showed that L-theanine is processed in the liver to become ethylamine, which acts to prime certain infection-fighting T cells of the immune system. As a result of this priming, the immune system is stimulated to attack sources of infection such as bacteria, viruses, and fungi. Bukowski and colleagues found that five cups of tea a day were enough to significantly enhance the body’s defenses against disease.
In recent years, scientific documentation has finally started to unravel the truth behind folklore benefits long-ascribed to green tea. Initial studies have indicated promising advantages in using green tea as an auxiliary measure in fighting cancer, obesity, heart disease, osteoporosis, and even general infection. Further studies and clinical trials are required however to clarify and fully utilize these disease fighting properties.
