What Is It?
Legend has it that in ancient times, a Chinese emperor was drinking some hot water when leaves from a nearby tea shrub (Camellia sinensis) dropped into his cup. He apparently liked the soothing drink that resulted from this chance event. And so began what is today a worldwide love affair with tea. It’s now second only to water as the most popular drink in the world.
Interestingly, research studies in recent years have confirmed the presence of various healing substances that provide the therapeutic properties long ascribed to the ubiquitous tea leaf. Of particular importance are potent antioxidant chemicals called polyphenols that help guard against many kinds of basic cell damage.
To prepare green tea, the leaves of Camellia sinensis are steamed, rolled, and dried. Black and oolong teas come from the same plant, but the leaves are processed differently (they are fermented) and therefore don’t provide the same types of therapeutic effects as green tea does. Products labeled gunpowder tea are also green tea. These pellets, imported from China, are just tightly compressed green tea leaves that will unfold when steeped.
In addition to the tea, a number of different forms of green tea supplements are now available.
Green tea is well-established as a potent source of healing antioxidants–the same beneficial compounds found in fruits and vegetables, and even in red wine. The leaf also boasts the presence of a superstar antioxidant called EGCG (epigallocatechin-gallate) as well as other notable healing substances, including fluoride, catechins, and tannins.
Many of the medicinal claims made for green tea haven’t been examined outside a laboratory setting, specifically in clinical trials that assess the plant’s health effects in people. On the other hand, the pure research findings are exciting, and there certainly appears to be no harm in integrating this ancient brew (or green tea supplements) into your daily diet.
For example, ongoing research suggests that thanks to its numerous and varied antioxidant compounds, sipping green tea regularly may help to prevent various types of cancer, guard against heart disease by lowering cholesterol levels and reducing blood pressure, promote longevity, stave off tooth decay (the tea contains the cavity fighter, fluoride), help heal gum infections, and provide a number of other benefits.
Researchers have found that only about 10 ounces of green tea will significantly increase the body’s antioxidant capacity for at least two hours. These increases are similar to those reported after drinking 10 ounces of red wine, another famed source of antioxidants; however, wine should be limited as a health drink because of its alcoholic content.
Because it contains astringent tannin compounds, green tea in moderation can ease indigestion, diarrhea, and other forms of stomach upset. Swiss researchers even have preliminary evidence that green tea accelerates the burning of fat calories in people who are overweight. A small but interesting 1999 study reported in the American Journal of Clinical Nutrition reported increased energy expenditure and fat oxidation in men who took a green tea extract as opposed to a placebo or caffeine alone.
Specifically, green tea may help to:
Prevent cancer. The antioxidant EGCG sets in motion a process called apoptosis. Interestingly, the cell death that ensues only affects cancer cells, not healthy ones. EGCG may well enhance the body’s natural antioxidant system as well, encouraging the elimination of damaging oxygen molecules called free radicals.
One large-scale study in China found that people who drank as little as one cup of green tea a week for six months had a reduced risk of developing certain kinds of cancers (rectal, pancreatic, and others) than did people who drank green tea less frequently or not at all. Other preliminary research indicates that green tea can help to combat breast, stomach, and skin cancer.
Counter aging. Given the latest findings on the potent antioxidants in green tea, it’s no wonder that this brew has long been touted for promoting long life. Its high antioxidant concentrations apparently enhance longevity by fighting heart disease and cancer, among other ailments. According to epidemiologic studies, Japanese men and women who drink five to 10 cups of green tea daily are more likely to live longer (they’re also more likely to stay cancer- and heart disease-free).
Treat arthritis. Antioxidants in green tea may prevent and reduce the severity of osteoarthritis. Studies have shown that if you consume approximately four cups of green tea a day you may be able to protect yourself from developing arthritis, and if you already have arthritis, consuming green tea can help to diminish the inflammation it causes.
Special tips: –Green tea capsules provide a more potent antioxidant effect than a cup of green tea: Green tea leaf is 8% to12% polyphenols (the key antioxidants) while the capsules can contain anywhere from 50% to 90% polyphenols, depending on the brand.
–To get an adequate amount of polyphenols, you need three to four cups of green tea a day or 100 mg of the extract in capsule form. What you do is largely a matter of personal taste. If you want to make green tea your mealtime beverage (as they do in Japan), then obviously you don’t need to take extract capsules. If you drink just one cup a day, you’re better off with a capsule.
–Antioxidant researchers say that two 8-ounce cups of green tea contain about as many flavonoids (a type of antioxidant) as a serving of vegetables or fruit.
For cancer prevention, anti-aging protection, and arthritis pains: Drink 3 or 4 cups of green tea a day.
Guidelines for Use
The healing properties of green tea can be derived from all its forms, but brewing the tea may certainly be the most pleasant way to ingest it. Of course, the taste of green tea may not appeal to everyone. A generous dollop of honey makes it more palatable for some people.
Preparing the tea with loose leaves provides no benefit over tea bags, but do try to find bags that haven’t been lying around for months.
For a caffeine-free product, look for decaffeinated green tea to brew or, better yet, switch to capsules, many of which don’t contain any caffeine to begin with.
It doesn’t appear to matter what time of day you drink green tea, although doing so throughout the day may be the most beneficial because you get a constant supply of antioxidants. And remember, green tea does contain caffeine, so drink the brew earlier in the day if you find that it keeps you awake at night.
Take green tea supplements at meals with a tall glass of water to ensure optimal absorption and effectiveness.
Although there are topical forms of green tea extract available (often in shampoos, skin creams, and other products), they provide no apparent health benefits.
There are no known drug or nutrient interactions associated with green tea.
Claims that high concentrations of vitamin K in green tea leaves can pose blood clotting problems, particularly in people taking anticoagulant medications for heart disease or other problems, have been discounted; the amount of vitamin K in an 8-ounce cup of brewed tea (or in a supplement pill) is negligible.
Possible Side Effects
Most of the side effects of green tea are the result of its caffeine content. Most green tea supplements have very little caffeine, about 5 to 6 mg in two 250 mg pills. One cup of brewed tea, however, has about 40 mg of caffeine. If you drink excessive amounts of brewed tea, you may experience caffeine-related irritability, sleeplessness, irregular heartbeat, dizziness, vomiting, diarrhea, headache, or loss of appetite.
Use green tea supplements (which are very low in caffeine) instead of drinking the tea while breast-feeding; the caffeine in the tea can affect a baby’s sleep habits adversely.
Never brew or drink green tea with boiling water; the high temperature can destroy valuable therapeutic compounds and sipping such hot tea may harm the throat and esophagus.
Aging 250 mg extract twice a day
Cancer Prevention 100 mg twice a day; may be partially covered by daily antioxidant complex
David Edelberg, MD