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For centuries, doctors, healers and tea drinkers have known that green tea possesses remarkable healing properties. Today, after decades of research, it’s become apparent that green tea truly is a "steaming cup of medicine." The results of hundreds of studies performed by top scientists at leading universities and research centers demonstrate that green tea, even in moderate amounts, may help ward off or combat a variety of ailments by:
- Boosting the immune system
- Regulating cholesterol levels
- Fighting the build-up of sticky plaque in the arteries
- Interfering with the cancer process
- Assisting in weight loss
- Fighting harmful bacteria and viruses
- Protecting the body against free radical damage
What is Green Tea?
Tea is a hot water infusion made from the leaves of the camellia sinensis bush. The way the leaves are processed determines whether the result is green, black or oolong tea. For green tea, the leaves are steamed or pan-fired immediately after picking to prevent them from fermenting. For black tea, the leaves are crushed and left to wither to encourage fermentation. For oolong, the leaves are withered for a shorter time, so they become only partially fermented.
Unfermented tea leaves contain large amounts of catechins, which are the powerful antioxidants and disease fighters responsible for green tea’s many health benefits. And while you can find some catechins in black and oolong tea, they’re found in much larger quantities in green tea. It’s the quick processing of green tea that keeps the catechins in place. When tea leaves are allowed to ferment, the catechins convert to another form that doesn’t have nearly as many health benefits. There are five types of catechins, but the most potent is epigallocatechin gallate (EGCg, for short).
Most studies have concluded that you need 3-10 cups of green tea per day, or up to 1,000 mg. of catechins for maximum health benefits. (The average 6-ounce cup of green tea contains between 50 and 100 mg catechins.)
What Can Green Tea Do For Your Health?
A wealth of laboratory, animal and human studies has provided evidence that green tea can help promote heart health, ward off cancer, fight obesity, lessen free radical damage to the cells, and even slow the progression of age-related cognitive impairment and Alzheimer’s disease. Samples of some interesting findings:
Green Tea and Cholesterol
Many researchers believe that green tea helps reduce cholesterol by lowering its absorption in the digestive tract and increasing its excretion.
Italian researchers studying two groups of volunteers following a controlled diet found that those who drank two cups of green tea (about 250 mg of catechins) per day for 6 weeks reduced their LDL "bad" cholesterol by an average of 13 mg/dl.1
A double blind, randomized, placebo-controlled study involving 240 people with mildly to moderately-elevated cholesterol found that taking 375 mg of theaflavin-enriched green tea extract daily for 12 weeks caused a reduction in total cholesterol of 11.3% and in LDL cholesterol of 16.4%, while the HDL "good" cholesterol increased by 2.3%.2
Animal studies have shown that even when consuming a diet rich in lard and cholesterol, rats who receive green tea catechins have much lower cholesterol levels than those who don't receive the catechins.3
Green Tea and Cardiovascular Disease
Green tea is associated with a reduction in many risk factors for cardiovascular disease. Besides improving cholesterol values, it may also help lower blood pressure, decrease blood stickiness, and prevent of LDL oxidation (a crucial beginning step in the atherosclerotic process). And while no one has actually proven that green tea can prevent heart disease, some recent findings are exciting:
A study of nearly 400 people scheduled for coronary angiography found that those who drank at least 1 cup of green tea per day were 42% less likely to have a heart attack than those who didn’t drink green tea.4
Green tea may also reduce a person’s risk of dying of a heart attack. Researchers interviewed 1900 people four days after having a heart attack. Four years later, those who consumed tea in moderate amounts (about 2 cups per day) decreased their risk of dying by 31%, while those who drank more than 2 cups per day decreased their risk by 39%.5
Green tea seems to be particularly protective against stroke-induced deaths. In a 2006 study, researchers who had been tracking 40,530 Japanese age 40 or older over an 11-year period reported that women who drank five or more cups of green tea daily were 42% less likely to die of a stroke than those who drank less than one cup.6
Green Tea and Obesity
Green tea has recently become the latest weapon in the war on weight. But does it really work? The results of some new studies are promising, finding that green tea can increase the rate of calorie burning, reduce body fat levels and even prevent excess weight gain. Although most tests have been performed on laboratory animals, at least one with humans showed that taking in the equivalent of 3 cups of green tea per day burned an additional 80 calories per day.
In a study of energy expenditure in men, those who took green tea extract containing EGCg plus caffeine three times daily burned about 80 more calories per day than those who didn't take the extract. (Taking caffeine with EGCg didn't have the same effect.) They took in roughly the amount of EGCg found in 3 cups of green tea a day.7
In another study, green tea extract actually helped prevent obesity. Two groups of mice were placed on a high-fat diet that ensured weight gain, and one group also received green tea extract, while the other did not. The mice that got the green tea extract gained 47% less weight than those who didn't get the extract.8
Finally, green tea extract helped to reverse established obesity. Rats that had become obese through deliberate overfeeding had their obesity reversed by supplementation with EGCg, which markedly decreased the amount of adipose tissue.9
Green tea is believed to help prevent obesity by revving up the fat-burning effects of brown fat, sending glucose to muscle tissue where it’s more likely to be burned, rather than to fat tissue, and inhibiting the action of fat-digesting enzymes so the fat that you eat is less available to the body.
Green Tea and Cancer
Animal studies have clearly shown that green tea can help prevent the growth of tumors in the breast, prostate, lung and skin. And many studies of large populations have linked green tea to a reduction of cancer of the stomach, lung, pancreatic, breast, colon, esophageal, prostate and skin.
Green tea’s catechins (particularly EGCg) appear to inhibit the cancer process at all stages. Specifically, they protect the body from free radical damage by acting as an antioxidant, lower the toxicity of certain carcinogens, interfere with the binding of carcinogens to the DNA of healthy cells, inhibit cancer activation, slow tumor growth and spread, inhibit the growth of blood vessels to feed the tumor, and encourage cancer cells to “commit suicide” (programmed cell death). Some of the more interesting studies of green tea’s effects on cancer include:
Stomach Cancer
Researchers from Shanghai, China compared 206 people newly diagnosed with stomach cancer to 415 healthy control subjects. After studying the volunteers’ health, diet and lifestyle habits, the researchers concluded that drinking green tea reduced the risk of developing stomach cancer by as much as 41%.10
Lung Cancer
The diet and lifestyle habits of 649 nine women with lung cancer were compared to those of 675 healthy women. The researchers found that drinking green tea reduced the risk of developing green tea by as much as 35% (in the nonsmokers only), and that the more green tea consumed, the greater the protection.11
Breast Cancer
A study of 1,100 Asian-American women, half of whom had breast cancer, showed that those in the non-cancer group were much more likely to be green tea drinkers. The researchers concluded that "green tea drinkers showed a significantly reduced risk of breast cancer..." and the more green tea consumed, the greater the protection.12
The combined results four studies (a meta-analysis) showed a 12% reduction in risk of developing breast cancer for those drinking the most green tea compared to those drinking the least.13
Pancreatic Cancer
A case-control study of cancer of the pancreas involving over 200 people found a significantly decreased risk of developing the disease in those who consumed green tea.14
Another study found that those who drank 2 or more cups of green tea per day had a 60% lower risk of developing pancreatic cancer.15 In test-tube studies, green tea has been shown to fight pancreatic cancer by damaging the mitochondria of the cancer cells and inhibiting cancer activation.16
Prostate Cancer
A double-blind, placebo-controlled study of green tea’s ability to fight prostate cancer was published in Cancer Research in 2006. Sixty men with HG-PIN, a condition that can quickly progress to prostate cancer, were divided into two groups. One group received 600 mg of green tea catechins per day; the other did not. After one year, only one prostate tumor was found among the green tea group compared to 9 in the control group.17
Skin Cancer
Much of the research of green tea’s effects on skin cancer has been done on hairless mice since their skin is very similar to human skin. And it’s been found that green tea extract, whether taken internally or painted on the skin, does help prevent skin cancer at both the induction and promotion phases. Mice given green tea extract in their drinking water for 50 days, then injected with a powerful skin cancer-inducing substance, got 44% fewer skin tumors than rats that hadn’t been given the extract.18 In another study, mice exposed to UVB rays who received green tea catechins through their water supply developed 41% fewer skin tumors than mice treated in the same manner, who didn’t get green tea. The tumors that they did develop were smaller.19 And recent test-tube studies have found that EGCg inhibits the growth and spread of the deadly skin cancer melanoma.20
Green Tea, the Health Elixir
Perhaps the Japanese Buddhist monk Eisai was right when he wrote circa 1211 that “Tea is a miraculous medicine for the maintenance of health.” Countless studies have shown that not only can green tea aid in heart health, interfere with the cancer process and help ward off obesity, it can also fight deadly bacteria, including the kind that cause tuberculosis21, guard against dental cavities22,23, inhibit the action of viruses24, fight free radical damage to the cells25 and preserve the freshness of foods26,27 and cosmetics.
How Much Do You Need?
Most experts agree that a daily intake of 3-10 cups of green tea (the equivalent of 300-1,000 mg of catechins) is ideal for maximum health benefits. In extract form, to get 300 mg of catechins you’d need to take about 480 mg of a 50:1 extract containing 60% catechins (60% of 480 mg = 300 mg).
But even a single cup of green tea per day can be beneficial (just this small amount confers powerful protection against dental cavities and breast cancer). So pour yourself a steaming cup of medicine and enjoy! It could be the beginning of a life-long love affair with a potent and delightful health-enhancer.
