Green tea comes from the Camellia sinensis plant, the same plant that produces black tea and oolong tea. Different types of processing determine the tea classification. Green tea does not undergo fermentation, and as a result it contains the highest antioxidant levels of the three types of tea. Touted as beneficial for weight loss, heart disease, cancer and even tooth decay, green tea seems like a near-perfect beverage. Unfortunately, you can get too much of a good thing. In addition to its potential benefits, green tea has a few drawbacks.
Green Tea Properties
Green tea contains polyphenols that serve as antioxidant agents. Antioxidants neutralize free radicals, which are compounds that can damage cells in the body and contribute to aging and the development of disorders like cancer, according to the University of Maryland Medical Center. Green tea also contains tannins and caffeine, which can cause undesirable effects.
Caffeine stimulates the central nervous system, and can trigger anxiety, insomnia, tremors, heart palpitations, loss of appetite and irritability, reports the "Gale Encyclopedia of Alternative Medicine." Green tea's tannin content might make some people nauseous, and it might inhibit the absorption of iron from foods or supplements.
The risk of side effects increases proportionally with the amount of green tea you drink. Steeping time is also a factor. Individual teabags are available in health food stores, as well as many grocery stores, and one teabag contains about 2 tsp. of tea leaves. To minimize the amount of caffeine and tannins you consume, the "Gale Encyclopedia" recommends steeping a teabag for no longer than five minutes and drinking no more than 300mg, or three to four cups of green tea per day.
Green tea is generally recognized as safe, or GRAS, but consuming the tea might stimulate gastric acid, making it inadvisable for people with ulcers, reports the "Gale Encyclopedia." In addition, pregnant women, breastfeeding mothers and people with kidney disease or heart disease should not drink green tea, unless directed to do so by their doctors.
Green tea may interfere with medications you're currently taking, including drugs used to treat heart conditions, blood-thinning medications, sedatives, antibiotics, contraceptives and medications used to treat cancer. Your doctor is the best source of advice for determining whether drinking green tea is safe for you.