Research shows that taking products containing green tea antioxidants reduces the risk of prostate cancer in high-risk patients. But most early research has found that drinking higher amounts of green tea is not linked with a reduced risk prostate cancer. Also, taking green tea or green tea extracts does not seem to slow the progression of prostate cancer that has already been diagnosed. Early research suggests that taking green tea extract by mouth for 7 days reduces stress and increases calmness in healthy people. Population research suggests that drinking at least 3 cups of green tea daily is linked to a reduced risk of having a stroke.
An autoimmune disease that causes widespread swelling (systemic lupus erythematosus or SLE). Early research shows that green tea extract seems to improve symptoms and general health in people with lupus. Research suggests that using a footbath containing green tea extract for 15 minutes once daily for 12 weeks doesn't improve symptoms of athletes foot, but does improve skin condition. A type of inflammatory bowel disease (ulcerative colitis). Early research suggests that taking a specific green tea product twice daily for 8 weeks might improve inflammatory bowel disease and help people with this condition achieve remission. Early research suggests that gargling and swallowing green tea over 4 days is less effective than labdanum lozenges for reducing symptoms of upper respiratory tract infections. Infections of the kidney, bladder, or urethra (urinary tract infections or UTIs). A small study shows that adding green tea capsules to antibiotic treatment seems to reduce symptoms of UTI more than taking the antibiotic alone. Some early research suggests that taking green tea antioxidants twice daily for 2 years does not reduce the signs of sun damage to the face in women.
Also, applying a green tea cream and taking green tea by mouth daily seems to improve some aspects of skin aging in women, but overall appearance of skin does not seem to improve. However, some early research shows that drinking a beverage containing green tea antioxidants improves skin roughness, hydration, and elasticity in middle-aged women. Inability to become pregnant within a year of trying to conceive (infertility). White patches inside the mouth that are usually caused by smoking (oral leukoplakia). More evidence is needed to rate green tea for these uses. When taken by mouth : Drinking green tea is LIKELY SAFE for most healthy adults when consumed in moderate amounts (about 8 cups per day). Green tea extract is POSSIBLY SAFE for most people when taken by mouth for up to 2 years or when used as a mouthwash, short-term. In some people, green tea extract can cause stomach upset and constipation. Green tea extracts have been reported to cause liver and kidney problems in rare cases. Drinking green tea is POSSIBLY UNSAFE when consumed for a long time or in high doses (more than 8 cups per day). Drinking large amounts of green tea might cause side effects due to the caffeine content. These side effects can range from mild to serious and include headache, nervousness, sleep problems, vomiting, diarrhea, irritability, irregular heartbeat, tremor, heartburn, dizziness, ringing in the ears, convulsions, and confusion. Green tea also contains a chemical that has been linked with liver injury when used in high doses. When applied to the skin : Green tea extract is LIKELY SAFE when a specific, FDA-approved ointment (Veregen, Bradley Pharmaceuticals) is applied to the skin, short-term. Green tea is POSSIBLY SAFE when other green tea products are applied to the skin, short-term. Special Precautions & Warnings: Children : Green tea is POSSIBLY SAFE for children when taken by mouth in amounts commonly found in foods and beverages, or when used for gargling three times daily for up to 90 days. Not enough is known about safety of green tea extract when taken by mouth in children. However, cases of liver damage have been reported for adults who used green tea extract. Therefore, some experts recommend that children under the age of 18 years old do not take green tea extract. Pregnancy and breast-feeding : If you are pregnant or breast-feeding, drinking green tea is POSSIBLY SAFE in amounts of 6 cups per day or less. This amount of green tea provides about 300 mg of caffeine. Drinking more than this amount during pregnancy is POSSIBLY UNSAFE and has been linked to an increased risk of miscarriage and other negative effects. Also, green tea might increase the risk of birth defects associated with folic acid deficiency. In women who are nursing, caffeine passes into breast milk and can affect a nursing infant. Nursing mothers should closely monitor caffeine intake to make sure it is on the low side (2-3 cups per day).
High intake of caffeine by nursing mothers can cause sleep problems, irritability, and increased bowel activity in breast-fed infants. "Tired blood" (anemia) : Drinking green tea may make anemia worse. Anxiety disorders : The caffeine in green tea might make anxiety worse. Bleeding disorders : Caffeine in green tea might increase the risk of bleeding.
Don't drink green tea if you have a bleeding disorder. Heart conditions : Caffeine in green tea might cause irregular heartbeat. Diabetes : Caffeine in green tea might affect blood sugar control.