Green tea leaf extract
Green tea is safe for most adults. Green tea extract seems to be safe for most people for short-term use. In some people, green tea can cause stomach upset and constipation. Green tea extracts have been reported to cause liver problems.
Too much green tea, such as more than five cups per day, can cause side effects because of the caffeine. 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 seems to reduce the absorption of iron from food.
If you are pregnant or breastfeeding, green tea in small amounts is probably not harmful. Do not drink more than 2 cups a day of green tea. This amount of tea provides about 200 mg of caffeine. Consuming more than this amount has been linked to an increased risk of miscarriage and other negative effects...
What other names is Green Tea known by?
Camellia sinensis, Camellia thea, Camellia theifera, Constituant Polyphénolique de Thé Vert, CPTV, EGCG, Epigallo Catechin Gallate, Épigallo-Catéchine Gallate, Epigallocatechin Gallate, Extrait de Camellia Sinensis, Extrait de Thé, Extrait de Thé Vert, Extrait de Thea Sinensis, Green Sencha Tea, Green Tea Extract, Green Tea Polyphenolic Fraction, GTP, GTPF, Japanese Tea, Kunecatechins, Poly E, Polyphenon E, PTV, Té Verde, Tea, Tea Extract, Tea Green, Thé, Thé de Camillia, Thé Japonais, Thé Vert, Thé Vert de Yame, Thé Vert Sensha, Thea bohea, Thea sinensis, Thea viridis, Yame Green Tea, Yame Tea.
What is Green Tea?
Green tea is a product made from the Camellia sinensis plant. It can be prepared as a beverage, which can have some health effects. Or an "extract" can be made from the leaves to use as medicine.
Green tea is used to improve mental alertness and thinking.
It is also used for weight loss and to treat stomach disorders, vomiting, diarrhea, headaches, bone loss (osteoporosis), and solid tumor cancers.
Some people use green tea to prevent various cancers, including breast cancer, prostate cancer, colon cancer, gastric cancer, lung cancer, solid tumor cancers and skin cancer related to exposure to sunlight. Some women use green tea to fight human papilloma virus (HPV), which can cause genital warts, the growth of abnormal cells in the cervix (cervical dysplasia), and cervical cancer.
Green tea is also used for Crohn's disease, Parkinson's disease, diseases of the heart and blood vessels, diabetes, low blood pressure, chronic fatigue syndrome (CFS), dental cavities (caries), kidney stones, and skin damage.
Instead of drinking green tea, some people apply green tea bags to their skin to soothe sunburn and prevent skin cancer due to sun exposure. Green tea bags are also used to decrease puffiness under the eyes, as a compress for tired eyes or headache, and to stop gums from bleeding after a tooth is pulled.
Green tea in candy is used for gum disease.
Green tea is used in an ointment for genital warts. Do not confuse green tea with oolong tea or black tea. Oolong tea and black tea are made from the same plant leaves used to make green tea, but they are prepared differently and have different medicinal effects. Green tea is not fermented at all. Oolong tea is partially fermented, and black tea is fully fermented.
Is Green Tea effective?
There is some scientific evidence that drinking green tea can improve thinking skills, and might help lower cholesterol and other fats called triglycerides. Green tea consumption might also prevent or delay Parkinson's disease and possibly help to prevent cancer of the bladder, esophagus, and pancreas. But green tea does not seem to help prevent stomach cancer.
There isn't enough information to know if green tea is effective for the other conditions people use it for including: kidney disease, heart disease, kidney stones, tooth decay, and others.
Likely Effective for...
- Genital warts. A specific green tea extract ointment (, Bradley Pharmaceuticals) is FDA-approved for treating genital warts.
- High cholesterol. Taking green tea by mouth seems to lower cholesterol levels. Research suggests that consuming 145-3000 mg of green tea catechins, an antioxidants found in green tea, daily for up to 24 weeks reduces total cholesterol and low-density lipoprotein (LDL or "bad") cholesterol.
- Mental alertness. Drinking green tea and other caffeinated beverages seems to help people maintain mental alertness throughout the day. Combining caffeine with sugar as an "energy drink" seems to improve mental performance more than caffeine or sugar alone. Also, taking a combination of green tea extract and L-theanine for seems to improve memory and attention in people with mild mental problems.