Good question... and the answers you will get will be varied
Green tea from about.com
A University of California study on the cancer-preventative qualities of green tea concluded that you could probably attain the desired level of polyphenols by drinking merely two cups per day. On the other hand, a company selling a green tea capsule formula insists that ten cups per day are necessary to reap the maximum benefits.
How can you make sense of these conflicting claims? Given all the evidence,
it is probably safe to plan on drinking four to five cups of green tea per daily. If you're a real devotee, by all means drink more; but whether or not you'll derive added health benefits remains to be determined by further research
However, Auntie Maleficent says, green tea also has caffeine in it so i'd start slowly and not have 5 cups at once.. youmight get jittery if you aren't used to caffeine... and watch consumption after 2 -3 pm... so it won't interfere with sleep.
From
cancer.org
Description
Green tea is a drink made from the steamed and dried leaves of the Camellia sinesis plant, a shrub native to Asia. Black tea is also made from this plant, but unlike green tea, it is made from leaves that have been fermented. (This may reduce the levels of some compounds, such as antioxidants, in black tea.)
Overview
Some researchers believe green tea may have a protective effect against certain cancers because it contains antioxidants. However, results from human studies have been mixed. More research is needed to determine its role in cancer prevention.
How is it promoted for use?
Green tea is widely consumed in Japan, China, and other Asian nations and is becoming more popular in Western nations. Some reports indicate green tea may have the ability to help prevent cancers of the skin, esophagus, stomach, colon, pancreas, lung, bladder, prostate, and breast.
Green tea contains chemicals known as polyphenols, which have antioxidant properties. Catechins are the major group of polyphenols in green tea. The most important catechin seems to be epigallocatechin-3-gallate (EGCG). EGCG may cause cancer cells to die like normal cells do. It may also work by stopping new blood vessels from forming, a process called angiogenesis, thereby cutting off the supply of blood to cancer cells.
Herbalists use green tea and extracts of its leaves for stomach problems, vomiting, and diarrhea, and to reduce tooth decay, blood pressure, cholesterol levels, and blockages of the blood vessels in the heart that can lead to heart attacks. Green tea is also promoted as an herb that can prevent certain bacterial infections. In recent years, some researchers have suggested that black tea may also be effective in cancer prevention. These claims are currently being studied.
What does it involve?
The amount of green tea consumed varies widely, and it is not clear how much might be needed for beneficial effects. Three cups a day or more is the amount typically taken in Asian countries. Green tea is usually brewed using 1 to 2 teaspoons of the dried tea in a cup of boiling water or is steeped for 3 to 15 minutes.
Green tea extracts are also available in capsule form. Three capsules of green tea extract a day are often recommended by proponents, but this dosage and its effects remain uncertain. There is wide variation in the contents of these extracts. Because they are sold as dietary supplements in the Unites States (as opposed to drugs), companies that market them do not have to prove they are effective, or even safe, as long as they donÂ’t claim they can prevent, treat, or cure a specific disease. Unlike drugs, dietary supplements are not highly regulated in terms of ensuring the contents match what is described on the product label.
What is the history behind it?
The Chinese have been drinking green tea to promote good health for at least 3,000 years. In recent years, scientists have begun to study its health effects more closely in lab animals and in observational human studies.
What is the evidence?
Many lab studies in cell cultures and animals have shown green tea has activity against cancer cells. It is tempting to assume that it may therefore help prevent some cancers, but studies in humans have been mixed. Most human studies have been population-based studies done in East Asia, in which researchers compared tea drinkers with non-tea drinkers while trying to account for other lifestyle differences. These types of studies are complex, and it is often hard to draw firm conclusions from them.
Large population-based studies in East Asia generally have not found that green tea drinkers have a lower risk of breast, stomach, or colon cancers than non-tea drinkers. One study found that Asian-American women who drink green tea regularly have a lower risk of breast cancer than those who do not. A Chinese study found that green tea drinking was associated with fewer cancers of the esophagus for people who did not smoke. Other studies of green teaÂ’s ability to prevent or treat lung, prostate, bladder, or other cancers have yielded similarly mixed results.
While the results of lab studies have been promising, at this time there is no conclusive evidence that green tea can help prevent or treat any specific type of cancer in humans. Controlled, randomized clinical trials are needed to determine its effectiveness. Several studies are currently under way.
Are there any possible problems or complications?
Green tea is generally considered safe. Asians have consumed this tea for thousands of years with few dangerous side effects. However, some people may develop allergic reactions and should stop drinking it.
Drinking large amounts of tea may cause nutritional and other problems because of the caffeine content and the strong binding activities of the polyphenols.
Possible effects from too much caffeine are the major concern with green tea. Too much caffeine can lead to nausea, trouble sleeping, and frequent urination. Because caffeine acts as a stimulant, people with irregular heartbeats or who have anxiety attacks should be cautious in its use.
Women who are pregnant or breast-feeding should not drink green tea in large amounts. Caffeine can cross the placenta and be passed along in breast milk.
Relying on this type of treatment alone, and avoiding conventional medical care, may have serious health consequences
