Green tea, which is made from unfermented tea leaves, has long been used medicinally in traditional Chinese and Indian medical systems, according to the University of Maryland Medical Center, or UMMC. Supplements made from concentrated green tea extracts are used to treat a variety of conditions, but most of these uses are unproven and there can be risks. Talk to your doctor before taking green tea supplements.
Uses
A number of studies have suggested that green tea might help prevent a range of cancers including bladder, esophageal, ovarian, pancreatic, breast, colon, prostate and lung cancer. Most of this research has been done on tea drinkers and not those taking supplements. None of this research is strong enough to prove that green tea prevents cancer, according to UMMC. Other research has suggested that green tea might help lower cholesterol, open blocked arteries, control blood sugar in people with diabetes and treat liver disease. It may also help people lose weight by boosting the body's ability to burn calories and fat. But none of these uses is proven.
How It Works
Green tea contains high levels of polyphenols, a type of antioxidant that helps combat dangerous free radicals, which can damage cells and DNA. Polyphenols may also be able to prevent inflammation and swelling, according to MedlinePlus. The antioxidants in green tea supplements may help protect the heart and blood vessels. However, more research is needed to confirm these benefits.
Side Effects
Typical side effects include stomach upset and constipation. Green tea supplements can contain caffeine, which can cause side effects, according to the National Center for Complementary and Alternative Medicine, or NCCAM. These include insomnia, anxiety, headache, nervousness, tremor, ringing in the ears, irritability, indigestion, heart palpitations, dizziness, appetite loss, nausea and diarrhea.
Other Safety Concerns
In rare cases, green tea supplements have been linked to liver problems, although the link is not proved, according to NCCAM. Do not take green tea supplements if you have liver disease or if you develop symptoms of a liver problem such as abdominal pain, dark urine or yellowing of the skin. Green tea supplements may also worsen anemia, anxiety disorders, bleeding conditions, heart disease, diabetes, glaucoma, high blood pressure and osteoporosis. If you have any of these conditions, consult your doctor before taking green tea supplements.
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