Particularly, the EGCG content bensfits Arthritis exercises for joint stability offer protection. Trudel D, Weight management for athletes DP, Bairati I, Fradet V, Bazinet Geen, Fortifying gut motility Grden. If you have these symptoms, stop using green tea and see your healthcare provider right away. Adult Depending on the brand, 2 to 3 cups of green tea per day for a total of to mg polyphenols or to mg per day of standardized green tea extract is recommended.

Green tea extract benefits -

Rothenberg DO, Zhang L. Mechanisms underlying the anti-depressive effects of regular tea consumption. Pervin M, Unno K, Ohishi T, et al. Beneficial effects of green tea catechins on neurodegenerative diseases.

Zhang J, Wang A, Zhang X, et al. Association between tea consumption and cognitive impairment in middle-aged and older adults. BMC Geriatr.

Lin Y, Shi D, Su B, et al. The effect of green tea supplementation on obesity: A systematic review and dose-response meta-analysis of randomized controlled trials. Phytother Res. Chen IJ, Liu CY, Chiu JP, Hsu CH. Therapeutic effect of high-dose green tea extract on weight reduction: a randomized, double-blind, placebo-controlled clinical trial.

Clin Nutr. Xu R, Bai Y, Yang K, Chen G. Effects of green tea consumption on glycemic control: a systematic review and meta-analysis of randomized controlled trials.

Nutr Metab Lond. American Association for the Advancement of Science. Drinking plenty of tea may reduce the risk of developing type 2 diabetes, finds study in over a million adults. Nie J, Yu C, Guo Y, et al. Tea consumption and long-term risk of type 2 diabetes and diabetic complications: a cohort study of 0.

Am J Clin Nutr. National Cancer Institute. Tea and cancer prevention. Arfin S, Jha NK, Jha SK, et al. Oxidative stress in cancer cell metabolism. Antioxidants Basel. Gianfredi V, Nucci D, Abalsamo A, et al. Green tea consumption and risk of breast cancer and recurrence—a systematic review and meta-analysis of observational studies.

Abe SK, Inoue M. Green tea and cancer and cardiometabolic diseases: a review of the current epidemiological evidence. Eur J Clin Nutr. Zhou H, Wu W, Wang F, Qi H, Cheng Z. Tea consumption is associated with decreased risk of oral cancer: a comprehensive and dose-response meta-analysis based on 14 case-control studies MOOSE compliant.

Medicine Baltimore. Castiglioni S, Damiani E, Astolfi P, Carloni P. Influence of steeping conditions time, temperature, and particle size on antioxidant properties and sensory attributes of some white and green teas.

Int J Food Sci Nutr. Harvard T. Chan School of Public Health. Dai Q, Liu S, Jiang Y, et al. Recommended storage temperature for green tea based on sensory quality.

J Food Sci Technol. National Institutes of Health Office of Dietary Supplements. Dietary supplements: what you need to know. Use limited data to select advertising.

Create profiles for personalised advertising. Use profiles to select personalised advertising. Create profiles to personalise content. Use profiles to select personalised content.

Measure advertising performance. Measure content performance. Understand audiences through statistics or combinations of data from different sources. Develop and improve services. Studies of green tea and cancer in people have had inconsistent results. The National Cancer Institute does not recommend for or against using green tea to reduce the risk of any type of cancer.

A small number of studies suggests that both green and black tea might have beneficial effects on some heart disease risk factors, including blood pressure and cholesterol. The research has limitations though, including how the data was evaluated and differences in study populations, so no definite conclusions have been reached.

The National Center for Complementary and Integrative Health NCCIH is funding research on green tea and its extracts, including studies on new forms of green tea extracts for preventing symptoms of inflammatory bowel disease and for lowering cholesterol.

What Do We Know About Safety? Green tea, when consumed as a beverage, is believed to be safe when used in amounts up to 8 cups per day. Keep in mind that only the amount of added caffeine must be stated on product labels and not the caffeine that naturally occurs in green tea.

Drinking green tea may be safe during pregnancy and while breastfeeding when consumed in amounts up to 6 cups per day no more than about mg of caffeine. Drinking more than this amount during pregnancy may be unsafe and may increase the risk of negative effects.

Green tea may also increase the risk of birth defects associated with folic acid deficiency. Caffeine passes into breast milk and can affect a breastfeeding infant. Although uncommon, liver problems have been reported in a number of people who took green tea products, primarily green tea extracts in pill form.

People with liver disease should consult a health care provider before taking products with green tea extract. People taking green tea extracts, especially those with liver disease, should discontinue use and consult a health care provider if they develop symptoms of liver trouble such as abdominal pain, dark urine, or jaundice.

Green tea is an ingredient in many over-the-counter weight loss products, some of which have been identified as the likely cause of rare cases of liver injury. Green tea at high doses has been shown to reduce blood levels and therefore the effectiveness of the drug nadolol, a beta-blocker used for high blood pressure and heart problems.

It may also interact with other medicines. Keep in Mind. Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions. For More Information.

Using Dietary Supplements Wisely Know the Science: How Medications and Supplements Can Interact Know the Science: How To Make Sense of a Scientific Journal Article. NCCIH Clearinghouse The NCCIH Clearinghouse provides information on NCCIH and complementary and integrative health approaches, including publications and searches of Federal databases of scientific and medical literature.

Toll-free in the U. gov Email: info nccih. PubMed® A service of the National Library of Medicine, PubMed® contains publication information and in most cases brief summaries of articles from scientific and medical journals.

Office of Dietary Supplements ODS , National Institutes of Health NIH ODS seeks to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, supporting research, sharing research results, and educating the public.

gov Email: ods nih. Key References. Chung M, Zhao N, Wang D, et al. Dose-response relation between tea consumption and risk of cardiovascular disease and all-cause mortality: a systematic review and meta-analysis of population-based studies.

Advances in Nutrition. February 19, Filippini T, Malavolti M, Borrelli F, et al. Green tea Camellia sinensis for the prevention of cancer. Cochrane Database of Systematic Reviews. com on March 21, Skin cancer. The main polyphenol in green tea is epigallocatechin gallate EGCG.

Scientific studies suggest that EGCG and green tea polyphenols have anti-inflammatory and anticancer properties that may help prevent the development and growth of skin tumors. Stomach cancer. Laboratory studies have found that green tea polyphenols inhibit the growth of stomach cancer cells in test tubes, however, studies in people have been less conclusive.

In two studies that compared green tea drinkers with nondrinkers, researchers found that people who drank tea were about half as likely to develop stomach cancer and stomach inflammation as those who did not drink green tea.

However, a clinical study with more than 26, men and women in Japan found no association between green tea and stomach cancer risk.

Some studies even suggest that green tea may increase the risk of stomach cancer. Green tea may help reduce inflammation associated with Crohn disease and ulcerative colitis, the two types of IBD. If green tea proves to help prevent colon cancer, it would also help those with IBD because they are at higher risk for colon cancer.

Green tea has been used traditionally to control blood sugar levels. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. In people with type 1 diabetes, their bodies make little or no insulin, which helps convert glucose or sugar into energy.

Green tea may help regulate glucose in the body. Research also suggests that regular consumption of green tea may help manage type 2 diabetes.

Population-based studies have shown that men who drink more than 10 cups of green tea per day are less likely to develop liver problems.

Green tea also seems to protect the liver from the damaging effects of toxic substances such as alcohol. Animal studies have shown that green tea helps protect against liver tumors in mice. Results from several animal and human studies suggest that plant chemicals in green tea called catechins, may help treat viral hepatitis, an inflammation of the liver.

In these studies, catechin was used by itself in very high amounts. It is not clear whether green tea, which has a lower concentration of catechins, would have the same benefits.

It is important to note that 10 cups of green tea a day could cause problems due to high levels of caffeine. Ask your doctor about the best way to include green tea in your treatment. Clinical studies suggest that green tea extract may boost metabolism and help burn fat.

One study found that the combination of green tea and caffeine improved weight loss and maintenance in people who were overweight and moderately obese.

However, other studies show no benefit. Preliminary studies suggest that drinking green tea can help prevent dental cavities. More research is needed. Green tea may also be useful in inflammatory diseases, such as arthritis. Research suggests that green tea may help arthritis by reducing inflammation and slowing the breakdown of cartilage.

Chemicals in green tea may help treat genital warts, treat dermatologic conditions, and prevent symptoms of colds and flu.

Green tea may play a role in preventing Parkinson disease, cognitive decline, and osteoporosis. Studies also show that drinking green tea is associated with reduced risk of dying from any cause. Green, black, and oolong tea are all derived from the leaves of the Camellia sinensis plant.

Originally cultivated in East Asia, this plant grows as large as a shrub or tree. Today, Camellia sinensis grows throughout Asia and parts of the Middle East and Africa. People in Asian countries more commonly consume green and oolong tea while black tea is most popular in the United States.

Green tea is prepared from unfermented leaves, the leaves of oolong tea are partially fermented, and black tea is fully fermented. The more the leaves are fermented, the lower the polyphenol content and the higher the caffeine content.

Green tea has the highest polyphenol content while black tea has roughly 2 to 3 times the caffeine content of green tea. Researchers think the health properties of green tea are mostly due to polyphenols, chemicals with potent antioxidant potential.

In fact, the antioxidant effects of polyphenols seem to be greater than vitamin C. The polyphenols in green tea also give it a somewhat bitter flavor.

Polyphenols contained in teas are classified as catechins. Green tea contains six primary catechin compounds: catechin, gallaogatechin, epicatechin, epigallocatechin, epicatechin gallate, and apigallocatechin gallate also known as EGCG.

EGCG is the most studied polyphenol component in green tea and the most active. Green tea also contains alkaloids including caffeine, theobromine, and theophylline. They provide green tea's stimulant effects.

L-theanine, an amino acid compound found in green tea, has been studied for its calming effects on the nervous system. Most green tea dietary supplements are sold as dried leaf tea in capsule form.

Look for standardized extracts of green tea. There are also liquid extracts made from the leaves and leaf buds. The average cup of green tea contains 50 to mg polyphenols antioxidants.

Decaffeinated green tea products contain concentrated polyphenols. Caffeine-free supplements are available. Depending on the brand, 2 to 3 cups of green tea per day for a total of to mg polyphenols or to mg per day of standardized green tea extract is recommended.

Caffeine-free products are available and recommended. The use of herbs is a time-honored approach to strengthening the body and treating disease. However, herbs contain active substances that can trigger side effects and interact with other herbs, supplements, or medications.

For these reasons, people should take herbs with care, under the supervision of a practitioner knowledgeable in the field of botanical medicine.

People with heart problems or high blood pressure, kidney problems, liver problems, stomach ulcers, and psychological disorders, particularly anxiety, should not take green tea. Pregnant and breastfeeding women should also avoid green tea. People with anemia, diabetes, glaucoma, or osteoporosis should ask their health care provider before drinking green tea or taking an extract.

People who drink large amounts of caffeine, including caffeine from green tea, for long periods of time may experience irritability, insomnia, heart palpitations, and dizziness. Caffeine overdose can cause nausea, vomiting, diarrhea, headaches, and loss of appetite.

If you are drinking a lot of tea and start to vomit or have abdominal spasms, you may have caffeine poisoning. If your symptoms are severe, lower your caffeine intake and see your health care provider. If you are being treated with any of the following medications, you should not drink green tea or take green tea extract without first talking to your health care provider:.

Green tea may inhibit the actions of adenosine, a medication given in the hospital for an irregular and usually unstable heart rhythm. Green tea may increase the effectiveness of beta-lactam antibiotics by making bacteria less resistant to treatment. Caffeine, including caffeine from green tea, may reduce the sedative effects of these medications commonly used to treat anxiety, such as diazepam Valium and lorazepam Ativan.

Beta-blockers, Propranolol, and Metoprolol. Caffeine, including caffeine from green tea, may increase blood pressure in people taking propranolol Inderal and metoprolol Lopressor, Toprol XL.

These medications are used to treat high blood pressure and heart disease. Blood-Thinning Medications. People who take warfarin Coudamin should not drink green tea. Since green tea contains vitamin K, it can make this medication ineffective. Other compounds in green tea may slow blood clotting and therefore increase the blood-thinning effect of these medications.

You should not mix green tea and aspirin because they both prevent blood from clotting. Using the two together may increase your risk of bleeding. If you are taking medications that promote blood thinning, discuss green tea consumption with your physician. The combination of green tea and chemotherapy medications, specifically doxorubicin and tamoxifen, increased the effectiveness of these medications in laboratory tests.

However, the same results have not been found in studies on people. On the other hand, there have been reports of both green and black tea extracts affecting a gene in prostate cancer cells that may make them less sensitive to chemotherapy drugs.

For that reason, people should talk to their doctors before drinking black and green tea or taking tea extracts while undergoing chemotherapy. Clozapine Clozaril. The effects of the clozapine may be reduced if taken within 40 minutes after drinking green tea.

When taken with ephedrine, green tea may cause agitation, tremors, insomnia, and weight loss. Green tea has been shown to reduce blood levels of lithium, a medication used to treat bipolar disorder.

That can make lithium less effective. Monoamine Oxidase Inhibitors MAOIs. Green tea may cause a severe increase in blood pressure, called a "hypertensive crisis," when taken together with these drugs used to treat depression.

Examples of MAOIs include:. Birth control pills. Oral contraceptives can prolong the amount of time caffeine stays in the body, which may increase its stimulating effects. A combination of caffeine, including caffeine from green tea, and phenylpropanolamine, used in many over-the-counter and prescription cough and cold medications and weight loss products, may cause mania and a severe increase in blood pressure.

The FDA issued a public health advisory in November to warn people of the risk of bleeding in the brain from use of this medication and urged all manufacturers of this drug to remove it from the market.

Most drugs that contained phenylpropanolamine have been reformulated without it. Quinolone antibiotics. Green tea may make these medications more effective and also increase the risk of side effects. These medications include:.

Other medications. Green tea, especially caffeinated green tea, may interact with a number for medications, including:. To be safe, check with your health care provider before drinking or taking green tea if you also take other medications.

Baladia E, Basulto J, Manera M, Martinez R, Calbet D. Effect of green tea or green tea extract consumption on body weight and body composition: systematic review and meta-analysis.

Nutr Hosp. Belza A, Toubro S, Astrup A. The effect of caffeine, green tea and tyrosine on thermogenesis and energy intake. Eur J Clin Nutr.

Bettuzzi S, Brausi M, Rizzi F, Castagnetti G, Peracchia G, Corti A. Chemoprevention of human prostate cancer by oral administration of green tea catechins in volunteers with high-grade prostate intraepithelial neoplasia: a preliminary report from a one-year proof-of-principle study.

Cancer Res. Borrelli F, Capasso R, Russo A, Ernst E. Systematic review: green tea and gastrointestinal cancer risk.

Aliment Pharmacol Ther. Mar 1, ;19 5 Boschmann M, Thielecke F. The effects of epigallocatechingallate on thermogenesis and fat oxidation in obese men: a pilot study.

J Am Coll Nutr. Brown AL, Lane J, Holyoak C, Nicol B, Mayes AE, Dadd T. Health effects of green tea catechins in overweight and obese men: a randomised controlled cross-over trial.

Fortifying gut motility NCCIH Immune-boosting supplement provides information on NCCIH and complementary beenefits integrative health approaches, including publications tex searches of Benefite databases of scientific Arthritis exercises for joint stability medical literature. The Clearinghouse does not extrwct medical advice, treatment recommendations, or referrals to practitioners. Email: info nccih. gov link sends email. A service of the National Library of Medicine, PubMed® contains publication information and in most cases brief summaries of articles from scientific and medical journals. For guidance from NCCIH on using PubMed, see How To Find Information About Complementary Health Approaches on PubMed.