Name: Green Tea - Standardized Extract
Scientific Name: Camellia Sinensis
Intro: Green tea is one of many teas consumed around the world today, but the only one widely known for its health benefits. Green tea is made from unfermented leaves and is reputed to contain the highest concentration of polyphenols, chemicals that act as powerful antioxidants. Antioxidants are substances that scavenge free radicals -- damaging compounds in the body that alter cell membranes, tamper with DNA (genetic material), and even cause cell death. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.
In traditional Chinese and Indian medicine, green tea has been used 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, regulating body temperature and blood sugar, promoting digestion, and improving mental processes.
Nutrient Content: The healthful properties of green tea are largely attributed to polyphenols, chemicals with potent antioxidant properties. In fact, the antioxidant effects of polyphenols appear to be greater than vitamin C. The polyphenols in green tea also give it its somewhat bitter flavor.
Polyphenols contained in teas are classified as catechins. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate (also known as EGCG). EGCG is considered to be the most active component in green tea and is the best researchered of all the green tea polyphenols. Green tea contains roughly 30% to 40% polyphenols and black tea contains only 3% to 10% polyphenols.
Green tea also contains alkaloids including caffeine, theobromine, and theophylline. These alkaloids provide green tea's stimulant effects.
Benefits:
Comments: The Dietary Supplements Information Bureau recommends a daily dosage of 250-500 mg of standardized extract for optimal health.
Caution: Contains a small amount of caffeine and, therefore, should not be used in large quantities by pregnant women or nursing mothers
Persons with anxiety disorders or irregular heartbeat should use intake green tea extract with caution
People with heart problems, kidney disorders, stomach ulcers, and psychological disorders (particularly anxiety) should not take green tea
Possible Interactions
If you are currently being treated with any of the following medications, you should not drink green tea or take green tea extract without first talking to your healthcare provider:
Adenosine
Green tea may inhibit the actions of adenosine, a medication administered in a hospital setting 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
Green tea should not be taken with warfarin, a blood-thinning medication, because the herb contains vitamin K and, thus, can render warfarin ineffective.
Similarly, green tea and aspirin should not be mixed because they both prevent platelets from clotting. Using the two together, therefore, 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. These results have not yet been demonstrated in studies of people, however.
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, black and green tea (as well as extracts of these teas) should not be taken while receiving chemotherapy for prostate cancer in particular.
Clozapine
The anti-psychotic effects of the medication clozapine may be reduced if taken less 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 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.