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green tea leaves

© 2018 Steven Foster

A green tea monograph for the home

Latin Name: Camellia sinensis

Common Name: green tea


This green tea monograph provides basic information about green tea—common names, usefulness and safety, and resources for more information.

Source: https://nccih.nih.gov/

Green Tea Basics

  • Green, black, and oolong teas all come from the same plant, Camellia sinensis, but are prepared using different methods. To produce green tea, fresh leaves from the plant are lightly steamed.
  • Tea has been used for medicinal purposes in China and Japan for thousands of years.
  • Current uses of green tea as a beverage or dietary supplement include improving mental alertness, relieving digestive symptoms and headaches, and promoting weight loss. Green tea and its extracts, such as one of its components, EGCG, have been studied for their possible protective effects against heart disease and cancer.
  • Green tea is consumed as a beverage. It is also sold in liquid extracts, capsules, and tablets and is sometimes used in topical products (intended to be applied to the skin).

Green Tea in Health Research

  • Although many studies have been done on green tea and its extracts, definite conclusions cannot yet be reached on whether green tea is helpful for most of the purposes for which it is used.

Green Tea Health Summary

  • There’s evidence that green tea enhances mental alertness, as would be expected because of its caffeine content.
  • The U.S. Food and Drug Administration has approved a specific green tea extract ointment as a prescription drug for treating genital warts.
  • 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.
  • Very few long-term studies have investigated the effects of tea on heart disease risk. However, the limited evidence currently available suggests that both green and black tea might have beneficial effects on some heart disease risk factors, including blood pressure and cholesterol.
  • Green tea extracts haven’t been shown to produce a meaningful weight loss in overweight or obese adults. They also haven’t been shown to help people maintain a weight loss.
  • The National Center for Complementary and Integrative Health (NCCIH) is funding research on green tea and its extracts, including studies of the effects of high doses of tea components on the liver, whether substances in green tea can be helpful for iron overload disease, and the safety of a component of green tea in people who are HIV-positive.

Green Tea Safety

  • Green tea, when consumed as a beverage, is believed to be safe when used in moderate amounts.
  • Liver problems have been reported in a small number of people who took concentrated green tea extracts. Although the evidence that the green tea products caused the liver problems is not conclusive, experts suggest that concentrated green tea extracts be taken with food and that people discontinue use and consult a health care provider if they have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice.
  • Except for decaffeinated green tea products, green tea and green tea extracts contain substantial amounts of caffeine. Too much caffeine can make people feel jittery and shaky; interfere with sleep; and cause headaches.
  • Green tea 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.

Green Tea References

 

PubMed Articles About


Source: National Center for Biotechnology Information (NCBI)[Internet]. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information; [1988] – [cited 2018 Apr 5]. Available from: https://www.ncbi.nlm.nih.gov/

Wang, CX., Wu, D., Yang, PP., Wu, QH., (2020) [Efficacy and safety of non-vitamin K antagonist versus vitamin K antagonist oral anticoagulants in the prevention and treatment of thrombotic disease in active cancer patients: a systematic review and meta-analysis of randomized controlled trials].

We aimed to compare the efficacy and safety of non-vitamin K antagonist oral anticoagulants (NOAC) and vitamin K antagonist (VKA) in the prevention and treatment of thrombotic diseases in patients with active cancer. To find randomized controlled trials (RCT) in which NOACs were compared VKAs in active cancer, we searched the electronic databases (PubMed, Web of Science and Clinical Trials) up to May 2019 and and languages restricted to Chinese and English. According to the screening strategy, two researchers independently screened and extracted literature, evaluated the quality of literature, the suitability of collected cross study data for analysis, and tested the heterogeneity. The relative risk () and 95% confidence interval (95%) of major bleeding, clinically related non-major bleeding, VTE, stroke and all-cause mortality in active cancer patients with VTE, active cancer patients with non-valvular atrial fibrillation (NVAF) was calculated and the results were compared between NOAC with VKA. A total of 9 RCTs were included, including 5 cancers with VTE (5/9) and 4 cancers with NVAF (4/9). A total of 5 867 patients were included. After excluding 1 818 (30.99%) patients with cancer history, 4 049 (68.86%) patients with active cancer were statistically analyzed. Among them, 2 278 (56.26%) received NOAC treatment, 1 771 patients (43.74%) received VKA treatment. The quality of the included documents was high (all scores were>5 points), and the data of each included document could be summarized and analyzed (>0.05). The heterogeneity of main outcome events was very low ( = 0). In VTE patients with active cancer, NOACs were more effective in reducing recurrence of VTE (=0.55, 95% 0.36 -0.84; 0.005) and clinically related non-major bleeding (=0.77, 95% 0.60 -0.98; 0.03) than VKAs. In NVAF patients with active cancer, efficacy of NOACs and VKAs was similar in terms of reducing VTE, stroke, clinically related non-major bleeding, major bleeding and all-cause mortality events (>0.05). For patients with active cancer accompanied by VTE, NOAC may has more advantages in efficacy and safety compared to VKA in the prevention and treatment of thrombotic diseases.

Zhang, ZD., Liu, H., Lyu, J., Yu, DD., Sun, MH., (2020) [Systematic review and Meta-analysis of efficacy and safety of Xiangsha Yangwei Pills in treatment of chronic gastritis].

To systematically evaluate the efficacy and safety of Xiangsha Yangwei Pills in the treatment of chronic gastritis. Compu-ter retrieval was performed for Cochrane Library, Medline, EMbase, China Knowledge Network Database(CNKI), China Biomedical Literature Service System(SinoMed), Chongqing Weipu Chinese Science and Technology Journal Database(VIP) and WanFang Database(WanFang) randomized controlled trials about Xiangsha Yangwei Pills combined with Western medicine in the treatment of chro-nic gastritis. The retrieval time ranged from the establishment of the library to April 26, 2019. Meta-analysis was performed by RevMan 5.3 software after two independent researchers conducted literature screening, data extraction and quality evaluation according to inclusion and exclusion criteria. A total of 1 720 patients were enrolled in 18 RCT. According to the classification of chronic gastritis, they were divided into three subgroups: chronic gastritis, chronic atrophic gastritis and chronic superficial gastritis. The results of Meta-ana-lysis showed that the efficacy of Xiangsha Yangwei Pills combined with Western medicine in treating chronic gastritis was higher than that of Western medicine. As for the recurrence rate, Xiangsha Yangwei Pills combined with Western medicine was lower than Western medicine. And there was no statistical difference about helicobacter pylori(Hp) eradication rate between Xiangsha Yangwei Pills combined with Western medicine as well as Western medicine. In terms of the incidence of adverse reactions, Xiangsha Yangwei Pills combined with Western medicine was lower than Western medicine, and no serious adverse reaction was reported. The results of this systematic review showed that compared with the conventional Western medicine group, Xiangsha Yangwei Pills combined with Western medicine can significantly alleviate clinical symptoms of chronic gastritis, with fewer adverse reactions. However, due to the low methodological quality of the included studies and the reliability of the impact conclusions, high-quality multi-center, large-sample, randomized, double-blind controlled trials are needed for validation.

Clifford, T., Jeffries, O., Stevenson, EJ., Davies, KAB., (2020) The effects of vitamin C and E on exercise-induced physiological adaptations: a systematic review and Meta-analysis of randomized controlled trials.

We conducted a systematic review and meta-analysis of randomized controlled trials examining the effect of vitamin C and/or E on exercise-induced training adaptations. Medline, Embase and SPORTDiscus databases were searched for articles from inception until June 2019. Inclusion criteria was studies in adult humans where vitamin C and/or E had to be consumed alongside a supervised exercise training program of ≥4 weeks. Nine trials were included in the analysis of aerobic exercise adaptations and nine for resistance training (RT) adaptations. Vitamin C and/or E did not attenuate aerobic exercise induced improvements in maximal aerobic capacity (O (SMD -0.14, 95% CI: -0.43 to 0.15,  = 0.35) or endurance performance (SMD -0.01, 95% CI: -0.38 to 0.36,  = 0.97). There were also no effects of these supplements on lean mass and muscle strength following RT (SMD -0.07, 95% CI: -0.36 to 0.23,  = 0.67) and (SMD -0.15, 95% CI: -0.16 to 0.46,  = 0.35), respectively. There was also no influence of age on any of these outcomes ( > 0.05). These findings suggest that vitamin C and/or E does not inhibit exercise-induced changes in physiological function. Studies with larger sample sizes and adequate power are still required.

Chen, G., Chen, Y., Chen, Z., Gao, S., Zhang, P., Zhang, H., Huang, Y., Lin, Y., Wei, L., (2021) Sanao decoction for asthma: Protocol of a systematic review.

Asthma is a chronic inflammatory disease characterized by recurrent attacks of breathlessness and wheezing, which often worsen at night or in the early morning and vary from person to person in severity and frequency. Sanao decoction (SAD), as a traditional Chinese medicine compound, has a long history of clinical application in the treatment of respiratory diseases. Whereas neither systematic nor meta-analysis of randomized controlled articles explain the efficacy of SAD in treating asthma. Therefore, we provide a protocol to evaluate the efficacy and safety of SAD for asthma.

Ahmad, I., Zaman, GS., Silvian, SP., Alshaharani, MS., Ahmad, I., Mansuri, N., Fayazuddin, S., (2021) Resistance training exercises for obese and non-obese individuals living in high-altitude regions utilizing biochemical markers-A controlled trial.

High-altitude disease prevalence varies according to types of exposure and the effects of hypoxic and hypobaric environments, with the result that people at high altitudes present many different physiological responses.