Green tea is a staple of cultures around the world, and only now are we getting to know the benefits of it in this country. Studies conducted on this beverage have shown some promise in helping heart disease, cancer and cholesterol, but more investigating is required to know the full scope of its worth. If you are considering adding green tea to your diet for the polyphenols, check with your doctor first. He can match it against your total medical history and make sure it is safe for you.
Types of Tea
There are four types of tea that have polyphenols in them: white, green, black and oolong. White teas are immature forms of the leaves and contain the highest amount of the chemical catechins, which contain polyphenols, according to the Linus Pauling Institute. Polyphenols are antioxidants that destroy free radicals, or toxins, that cause harm to the body. Green teas are next highest in polyphenols and are unfermented mature leaves. Black and oolong teas are processed so that they have very low amounts of catechins, but are high in other nutrients.
Theapeutic Uses
Polyphenol studies have looked at heart disease and cancer primarily. There is some evidence that green tea is effective against atherosclerosis, or hardening of the arteries. However, in 2006, the Food and Drug Administration would not allow tea makers to put that claim on their boxes and stated there was no evidence that green tea helped with heart disease, according to the University of Maryland Medical Center. Studies into its efficacy in fighting cancer are mixed. For example, animal studies show that polyphenols inhibit breast cancer, but some human studies show no affect. Green tea studies also focused on inflammatory bowel disease, diabetes, weight loss and liver disease.
Dangers and Interactions
Many people around the world drink tea with no side effects, but there are some considerations you should take if you decide to add tea to your lifestyle. Tea, when taken as a drink, contains large amounts of caffeine and can lead to anxiety, nervousness and insomnia. You could possibly get caffeine poisoning if you drink too much tea, according to the University of Maryland Medical Center. Symptoms include nausea, vomiting, diarrhea, headache and loss of appetite. Green tea can also cause extremely high blood pressure when taken with monoamine oxidase inhibitors, or MAOIs. Other drugs it can interact with are adenosine, blood thinners such as warfarin, lithium, birth control pills and beta-blockers such as metoprolol.
Dosages
In order to benefit from the polyphenols in green tea, you have to take a therapeutic dose of green tea every day. You can either drink the tea itself or take an extract in capsule form. The University of Maryland Medical Center recommends two to three cups of green tea per day for 240 to 320 mg of polyphenols. If you prefer the extract, 100 to 750 mg per day is recommended. Decaffeinated versions are available. However, some supplements had high amounts of lead in them, and there were also two cases of liver failure from extracts, according to New York University Langone Medical Center.
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