Green tea is said to bring down cholesterol levels and improve the ratio of high density lipoprotein (HDL) to low density lipoprotein (LDL) cholesterol. Moreover, it is also believed to boost the immune system and prevent cavities and tooth decay because of its bacterial-destroying properties.
Green tea drinks are now widely available in supermarkets, grocery stores, and food outlets. These come in bottles, cans, sachets, and dispensers.
Today, scientific researches in Asia and in the West are providing hard evidence on health benefits associated with drinking green tea over long periods. A study in China showed that drinking green tea reduced the risk of esophageal cancer among Chinese men and women by a cool 60 percent. Another University of Purdue study concluded that green tea inhibits growth of cancer cells.
The polyphenols found in green tea called catechin is a powerful anti-oxidant that inhibits growth of cancer cells and kills cancer cells without harming healthy tissues.
Links are also being made between the effects of drinking green tea and the "French paradox". For years, researchers were puzzled by the fact that despite a diet rich in fat, the French have lower heart disease incidence than Americans. The answer was traced to the French's consumption of red wine, which also contains polyphenol called resveratrol that limits the negative effects of smoking and a fatty diet.
In another study in Kansas University, researchers discovered that catechins in green tea is twice as powerful as resveratrol found in red wine. Another study at University of Geneva in Switzerland, researchers revealed that men, given a combination of caffeine and green tea extract, burned more calories than those given caffeine alone or placebo. Hence green tea aids in weight reduction.
To date, the only reported negative side effect from drinking green tea is insomnia because it contains caffeine. But it is still lower than the caffeine in coffee.
With these health benefits, one would ask: "How much green tea should be consumed?" There are many answers to this question as there are researchers investigating the natural properties of green tea.
Japanese researchers reported that men who drank ten cups of green tea per day stayed cancer-free three years longer than those who drank less. Another group of Japanese scientists in the Saitama Cancer Research Institute revealed that women with a history of drinking green tea five or more cups per day experienced fewer recurrences of breast cancer.
Another study by Cleveland's Western Reserve University claimed that drinking four or more cups of green tea daily could help prevent rheumatoid arthritis or reduce symptoms to those already suffering from the disease.
Still another University of California study said that drinking as few as two cups per day could be enough to attain the desired level of cancer prevention qualities of green tea.
On the other hand, a company selling green tea capsule formula said that swigging 10 cups per day are necessary to reap the maximum benefits.
How can these conflicting claims make sense to anyone's daily living? Given all the evidences, it is arguably safe to drink minimal amounts of green tea (one to three cups) per day. Whether drinking more will give added benefits remains to be determined by further research. It is generally advised that drinking green tea should not be made as a substitute to treatment regimen of any type of disease.
In general, 100g of dried green tea leaves yield energy (357kcal), protein (21.7g), carbohydrate (65.3g), dietary fiber (11.2g), calcium (656mg), phosphorous (258mg), iron (18.4mg), niacin (6.8mg), and water (7.4g).
The Food and Nutrition Research Institute of the Department of Science and Technology has been conducting studies on the role of functional foods like rootcrops, legumes, and coconut flour in lowering blood glucose and cholesterol levels. But no study so far has been done on green tea.