Green Tea – Magic Drink
Today, millions of people drink tea around the world, and it is now considered as one of the most widely consumed beverages in the world, second after drinking water. Multiple studies confirm the Eastern Medicine conclusions that drinking green tea (Camellia Sinesis) in particular has many outstanding benefits for your health. Green tea is a botanical that has been shown to protect people from many types of cancer, reduces inflammation, helps protect the liver, boosts metabolism and shows many other positive health effects.
There are three main varieties of tea — green, black, and oolong. The difference between the teas is in their processing. Green tea is made from unfermented leaves and reportedly contains the highest concentration of powerful antioxidants called polyphenols.
Antioxidants are substances that scavenge free radicals — damaging compounds in the body that alter cells, tamper with DNA (genetic material), and even cause cell death. Free radicals occur naturally in the body, but environmental toxins (including ultraviolet rays from the sun, radiation, cigarette smoke, and air pollution) also give rise to these damaging particles. Many scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems, including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.
Green tea has been consumed throughout the ages in India, China, Japan, and Thailand. In traditional Chinese and Indian medicine, practitioners used green tea as a stimulant, diuretic (to promote the excretion of urine), astringent (to control bleeding and help heal wounds), and to improve heart health. Other traditional uses of green tea include treating flatulence (gas), regulating body temperature and blood sugar, promoting digestion, and improving mental processes.
Green tea and pancreatic cancer
Green tea has so many health related advantages for humans, so it is not surprising that medical scientists are trying to look if it can be useful for pancreatic cancer prevention. Pancreatic cancer is famous by its difficulties and diagnostics, so in many cases, it is identified at the moment when the tumor is incurable. Therefore, it so important to identify ways of preventing this deadly disease, or, actually, decreasing the risk of getting it.
In the recent article "Green tea and the risk of pancreatic cancer and colon cancer," the group of researchers from Columbia University examined the question of the effectiveness of green tea as a remedy against certain types of cancer. This is a preliminary study and researchers admitted that the results are not statistically conclusive yet, suggesting to complement it with additional researches on animal and human. However, the results are quite positive, and may lay a trail to the future studies and consumer recommendations.
Testing the hypothesis of the ability of green tea regular consumption to influence the risk of getting several types of cancer, the researchers conducted extensive study in Shanghai, China. The research team found the direct correlation between drinking green tea and cancer development rates: the higher consumption of green tea led to the lower the risk of cancer. Therefore, it seems that green tea can, in fact, reduce the incidence of both colon and pancreatic cancer, which is especially important for the people having certain predisposition to the tumor development.
Another study has been performed, looking for the causal relationship between green tea drinking and risk of development of pancreatic cancer in particular. And the results were also encouraging, showing the substantial health related benefits. Interesting that the study showed general difference in results - significantly higher positive effect has been observed among females, where the risk of pancreatic cancer decreased 50%, while male green tea drinkers has shown just 37% of the risk decrease.
Definitely, more studies are needed, but based on these results, and general benefits of Green Tea, I would say that it is highly recommended to be included in your daily diet, especially when you read its health benefits for other functional systems of your body and mind.
Other health benefits
Only a few clinical studies have examined the relationship between bladder cancer and green tea consumption. In one study that compared people with and without bladder cancer, researchers found that women who drank black tea and powdered green tea were less likely to develop bladder cancer. A follow-up clinical study by the same group of researchers revealed that bladder cancer patients (particularly men) who drank green tea had a substantially better 5-year survival rate than those who did not.
Clinical studies in animals and test tubes suggest that polyphenols in green tea inhibit the growth of breast cancer cells. In one study of 472 women with various stages of breast cancer, researchers found that women who consumed the most green tea experienced the least spread of cancer (particularly premenopausal women in the early stages of breast cancer). They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to suffer recurrences of the disease after completion of treatment. However, women with late stages of breast cancer experienced little or no improvement from drinking green tea. In terms of breast cancer prevention, the studies are inconclusive.
In a clinical study conducted on ovarian cancer patients in China, researchers found that women who drank at least one cup of green tea per day survived longer with the disease than those who didn’t drink green tea. In fact, those who drank the most tea, lived the longest.
Laboratory studies have found that green tea extracts prevent the growth of prostate cancer cells in test tubes. In a large clinical study conducted in Southeast China researchers found that the risk of prostate cancer declined with increasing frequency, duration and quantity of green tea consumption.
The main polyphenol in green tea is epigallocatechin gallate (EGCG). Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anti-cancer properties that may help prevent the onset and growth of skin tumors.
Inflammatory Bowel Disease (IBD)
Green tea may help reduce inflammation associated with Crohn’s disease and ulcerative colitis, the two types of IBD. If green tea proves to be helpful for preventing colon cancer, this would be an added benefit for those with IBD because they are at risk for colon cancer.
Green tea has been used traditionally to control blood sugar in the body. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. People with type 1 diabetes produce little or no insulin, a hormone that converts glucose (sugar), starches, and other foods into energy needed for daily life. Green tea may help regulate glucose in the body. A few small clinical studies have found that daily supplementation of the diet with green tea-extract powder lowered the hemoglobin A1c level in individuals with borderline diabetes.
Population-based clinical studies have shown that men who drink more than 10 cups of green tea per day are less likely to develop disorders of the liver. Green tea also seems to protect the liver from the damaging effects of toxic substances such as alcohol. Animal studies have shown that green tea helps protect against the development of liver tumors in mice.
Results from several animal and human studies suggest that one of the polyphenols present in green tea, known as catechin, may help treat viral hepatitis (inflammation of the liver from a virus). In these studies, catechin was isolated from green tea and used in very high concentrations. It is not clear whether green tea (which contains a lower concentration of catechins) confers these same benefits to people with hepatitis.
Green tea also benefits your heart. A Japanese study found that drinking four cups of green tea may reduce the severity of coronary heart disease. A similar Dutch study found that green tea consumption correlated with less clogging of the coronary arteries. Because the antioxidants in green tea are dilators, consuming more green tea improves the flexibility of blood vessels and may make them less likely to become clogged.
Clinical studies suggest that green tea extract may boost metabolism and help burn fat. One study confirmed that the combination of green tea and caffeine improved weight loss and maintenance in overweight and moderately obese individuals. Some researchers speculate that substances in green tea known as polyphenols, specifically the catechins, are responsible for the herb’s fat-burning effect. Studies in Japan and the Netherlands have supported this claim. Participants in the Dutch study who drank the most green tea lost the most weight and body fat, had lower blood pressure, and had lower “bad” cholesterol.
Depending on the brand, 2 - 3 cups of green tea per day (for a total of 240 - 320 mg polyphenols) or 100 - 750 mg per day of standardized green tea extract is recommended. Caffeine-free products are available and recommended.
The use of herbs is a time-honored approach to strengthening the body and treating disease. However, herbs contain active substances that can trigger side effects and interact with other herbs, supplements, or medications. For these reasons, people should take herbs with care, under the supervision of a practitioner knowledgeable in the field of botanical medicine.
People who drink excessive amounts of caffeine (including caffeine from green tea) for prolonged periods of time may experience irritability, insomnia, heart palpitations, and dizziness. Caffeine overdose can cause nausea, vomiting, diarrhea, headaches, and loss of appetite. If you are drinking a lot of tea and start to vomit or have abdominal spasms, you may have caffeine poisoning. If your symptoms are severe, lower your caffeine intake and see your health care provider.
If you are being treated with any of the following medications, you should not drink green tea or take green tea extract without first talking to your health care provider:
Adenosine -- Green tea may inhibit the actions of adenosine, a medication given in the hospital for an irregular (and usually unstable) heart rhythm.
Antibiotics, Beta-lactam -- Green tea may increase the effectiveness of beta-lactam antibiotics by reducing bacterial resistance to treatment.
Benzodiazepines -- Caffeine (including caffeine from green tea) has been shown to reduce the sedative effects of benzodiazepines (medications commonly used to treat anxiety, such as diazepam and lorazepam).
Beta-blockers, Propranolol, and Metoprolol -- Caffeine (including caffeine from green tea) may increase blood pressure in people taking propranolol and metoprolol (medications used to treat high blood pressure and heart disease).
Blood Thinning Medications (Including Aspirin) -- People who take warfarin, a blood thinning medication, should not drink green tea. Since green tea contains vitamin K, it can make warfarin ineffective. Meanwhile, you should not mix green tea and aspirin because they both prevent platelets from clotting. Using the two together may increase your risk of bleeding.
Chemotherapy -- The combination of green tea and chemotherapy medications, specifically doxorubicin and tamoxifen, increased the effectiveness of these medications in laboratory tests. However, these results have not yet been demonstrated in studies on people. On the other hand, there have been reports of both green and black tea extracts stimulating a gene in prostate cancer cells that may cause them to be less sensitive to chemotherapy drugs. Given this potential interaction, people should not drink black and green tea (as well as extracts of these teas) while receiving chemotherapy for prostate cancer in particular.
Clozapine -- The antipsychotic effects of the medication clozapine may be reduced if taken fewer than 40 minutes after drinking green tea.
Ephedrine -- When taken together with ephedrine, green tea may cause agitation, tremors, insomnia, and weight loss.
Lithium -- Green tea has been shown to reduce blood levels of lithium (a medication used to treat manic/depression).
Monoamine Oxidase Inhibitors (MAOIs) -- Green tea may cause a severe increase in blood pressure (called a "hypertensive crisis") when taken together with MAOIs, which are used to treat depression. Examples of MAOIs include phenelzine and tranylcypromine.
Oral Contraceptives -- Oral contraceptives can prolong the amount of time caffeine stays in the body and may increase its stimulating effects.
Phenylpropanolamine -- A combination of caffeine (including caffeine from green tea) and phenylpropanolamine (an ingredient used in many over-the-counter and prescription cough and cold medications and weight loss products) can cause mania and a severe increase in blood pressure. The FDA issued a public health advisory in November 2000 to warn people of the risk of bleeding in the brain from use of this medication and has strongly urged all manufacturers of this drug to remove it from the market.
- Allow tea to steep for three to five minutes to bring out its catechins.
- The best way to get the catechins and other flavonoids in tea is to drink it freshly brewed. Decaffeinated, bottled ready-to-drink tea preparations, and instant teas have less of these compounds.
- Tea can impede the absorption of iron from fruits and vegetables. Adding lemon or milk or drinking tea between meals will counteract this problem.
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