Natural Standard Monograph, Copyright © 2014 (www.naturalstandard.com). Commercial distribution prohibited. This monograph is intended for informational purposes only, and should not be interpreted as specific medical advice. You should consult with a qualified health care professional before making decisions about therapies and/or health conditions.
Uses based on scientific evidence
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare professional.
Polyphenon E®, a green tea extract, has been FDA-approved for genital warts caused by the human papilloma virus (HPV). A study reports that Polyphenon E® ointment may have antioxidant, anti-inflammatory, and anticancer effects. Polyphenon E® ointment should be used under the care of a doctor or other health professional. Other research suggests that green tea creams may be useful for genital and anal warts and may be a less expensive alternative to regular treatment.
Research suggests that green tea may lower cholesterol; however, studies in people with high cholesterol are limited. Further study in people with this condition is needed before a firm conclusion can be made.
Research suggests that green tea may improve acne by blocking the bacteria that causes this condition. More study is needed to determine the possible benefits of green tea and green tea extract.
Limited research reports that benifuuki green tea reduced symptoms of hay fever caused by Japanese cedar. More studies are needed before a conclusion can be made.
Green tea contains an amino acid called L-theanine, which has been studied and compared to caffeine or alprazolam (Xanax®), for anxiety. L-theanine was found to have positive effects on anxiety under some conditions. However, more high-quality research is needed in this area.
Green tea has been found to have anti-inflammatory benefits. It has been considered for use in osteoarthritis and rheumatoid arthritis. However, research in humans is lacking. More research is needed.
Evidence is mixed from available research of green tea catechins for exercise performance. Further study in this field is needed.
Several reviews have discussed green tea for cancer prevention. Several large studies have looked for a possible link between green tea consumption and cancer incidence. Most research has focused on cancers of the digestive system (stomach, colon, rectum, pancreas, and esophagus), although the risk of breast and prostate cancer have also been studied. Early human research suggests that green tea lacks effect in treating cancer. Further study is needed before a conclusion can be made.
Polyphenols, compounds found in green tea, have been shown to have antiviral effects. Early research suggests that specific green tea formulas may help prevent cold and flu symptoms. In children, drinking one to five cups daily has been linked to a reduced risk of developing the flu. More studies are needed to confirm these results.
There has been limited human research looking at the use of green tea for cavities. Early study suggests that green tea may help decrease plaque. More information is needed before conclusions can be made.
Early research suggests that a combination product called FertilityBlend may help women become pregnant. However, there is a lack of study on the use of green tea alone for fertility. More information is needed in this area.
Gum disease (infection around the tooth)
Green tea intake may decrease signs of inflammation and infection of the tissues around the tooth. Research suggests that green tea extract as part of a combination therapy may help reduce gum bleeding. More well-designed trials are needed before a conclusion can be made.
Several large studies have looked for a possible link between green tea and measures of heart health. Studies have looked at cholesterol levels, blood pressure, and narrowed arteries, and have found a lack of benefit. More research is needed on the use of green tea for treating or preventing heart conditions.
High blood pressure
Early study suggests that green tea may increase blood pressure in people who have high-normal or mild high blood pressure. Recent research suggests that tea in general lacks effect on blood pressure. Other studies report that drinking green tea may help reduce the likelihood of developing high blood pressure. More clinical trials are needed in this area.
Human T-cell lymphocytic virus (carriers)
Early research suggests that green tea may reduce infection severity in people who carry the HTLV-1 virus, which causes cancer of immune system cells. More high-quality research is needed in this area.
Hypertriglyceridemia (high triglycerides)
Early study suggests that green tea may help reduce post-meal triglyceride levels in people who have high triglycerides. Additional research is needed in this area.
Some case reports suggest that green tea products may cause liver damage and inflammation. However, another review reports that increased green tea consumption may reduce liver disease risk. Further study is needed before firm conclusions can be made.
Early research suggests that taking a green tea-containing formula may help relieve menopause symptoms such as hot flashes and problems with sleep. More studies are needed on the effects of green tea alone.
Different types of tea contain different compounds that may help improve cognition. Caffeine may increase alertness and thought. Early non-human research looked at the effects of caffeine, tea, or coffee use on short- and long-term memory and alertness. In limited human research, benefits were lacking on mental performance, mood, and blood flow in the brain. More research is needed before conclusions may be made.
Green tea polyphenols may benefit bone health and quality of life in women with low bone density. However, evidence for bone mass is lacking. More research is needed before a conclusion can be made.
Studies suggest that catechins, the main compounds in green tea, may help fight infection. Green tea consumption has been linked to a lower risk of death from pneumonia in women. More research is needed before a conclusion can be made.
Limited study has found mixed results to support the use of green tea for skin aging caused by sun exposure. More research is needed in this area.
Tuberculosis (management of oxidative stress)
Green tea catechins may help reduce oxidative stress in people who have tuberculosis. More research is needed before a conclusion can be made.
Upper respiratory tract infection
Green tea was found to be less effective than CYSTUS052®, another plant extract, for symptoms of upper respiratory tract infection (infection of the nose or throat). Further research is needed in this area.
Green tea was included in a review of treatments for wound odor control. However, more well-designed studies related to green tea are needed before conclusions can be made.
Early research suggests that green tea may lack an effect on blood sugar or insulin levels in people with diabetes. In people without diabetes, blood sugar levels were higher two hours after a meal consumed with green tea, compared to a meal consumed with water. However, green tea consumption has been linked to a lower risk of diabetes in some research. More research is needed before a firm conclusion can be made.
There are mixed reports on green tea's effects on weight loss. Some research suggests a lack of effect on weight loss or maintenance of weight. Other research reports a small decrease in weight when caffeine was included with green tea. Further study is needed before firm conclusions can be made.
*Key to grades:
A: Strong scientific evidence for this use;B: Good scientific evidence for this use; C: Unclear scientific evidence for this use;D: Fair scientific evidence against this use (it may not work);F: Strong scientific evidence against this use (it likely does not work).
For full grading rationale, click here.
Uses based on tradition or theory
The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified health care professional
Age-related macular degeneration (retina breakdown leading to vision loss), aging, alcohol intoxication, amyotrophic lateral sclerosis (disease of nerve cells in brain and spinal cord), anthrax, antibacterial, anti-inflammatory, antioxidant, antiviral, astringent, blood thinner, cancer treatment side-effects, cataracts, Crohn's disease, dementia, diarrhea, digestion, food preservation, foul body odor (prevention), fungal infections, gas, general health maintenance (body temperature regulation), glaucoma (eye disease), gut disorders, H. pylori infection, hair growth, headache, HIV/AIDS, improving blood flow, improving resistance to disease, improving urine flow, ischemia-reperfusion injury protection (tissue damage caused by lack of oxygen), kidney stone prevention, leukoplakia (patches on mouth/tongue caused by irritation), metabolic disorders, nerve pain, nerve damage, pain (nipple from breastfeeding), Parkinson's disease (prevention), poisoning (general), prostate inflammation, protection against asbestos lung injury, sepsis (severe response to infection), skin disorders, stimulant, stroke prevention, sunburn, tired eyes, vomiting.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy. Consult a healthcare professional immediately if you experience side effects.
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare professional before starting a new therapy.
Natural Standard developed the above evidence-based information based on a systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.
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