Green Tea

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Green Tea Safety and Side Effects

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...

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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. The fresh leaves are used to make medicine.

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 (Veregen, Bradley Pharmaceuticals) is FDA-approved for treating genital warts.
  • Increasing mental alertness, due to the caffeine content of green tea.

Possibly Effective for...

  • Preventing dizziness upon standing up (orthostatic hypotension) in older people.
  • Preventing bladder, esophageal, ovarian, and pancreatic cancers.
  • Reducing the risk of Parkinson's disease.
  • Decreasing high levels of fat in the blood (hyperlipidemia).
  • Reducing abnormal development and growth of cells of the cervix (cervical dysplasia) caused by human papilloma virus (HPV) infection.
  • Low blood pressure. Green tea might help in elderly people who have low blood pressure after eating.

Possibly Ineffective for...

  • Preventing colon cancer.

Insufficient Evidence to Rate Effectiveness for...

  • Weight loss, high blood pressure, heart disease prevention, stroke prevention, osteoporosis, type 2 diabetes, skin cancer, breast cancer, lung cancer, stomach cancer, dental cavities, gingivitis, kidney stones, prostate cancer, diarrhea, chronic fatigue syndrome (CFS), and other conditions.

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, and Insufficient Evidence to Rate (detailed description of each of the ratings).


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