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Clinical Updates
Green Tea Supplements and Drinks
Benefits of Mullein Tea?
October 21, 2024
What is mullein tea and does it really reduce coughing, or help ward off the flu or other viruses? Find out in our new article about the potential health benefits and safety of mullein tea.
Also see our Green Tea Review, including our Top Picks.
Green Tea & Iron Deficiency
September 16, 2024
Severe iron-deficiency anemia was recently reported after regular consumption of green tea. Get the details in our Green Tea Review, which includes our Top Picks for green tea.
Also be aware that drinking green tea may significantly affect blood levels of a common beta-blocker, as well as statins, blood-thinners, and thyroid medication. See the Concerns and Cautions section of our Green Tea Review.
Matcha for Sleep?
September 12, 2024
Does taking green tea matcha powder before bedtime improve sleep? Find out what a recent study showed in the Sleep section of our Green Tea Supplements Review, which includes our Top Picks among matcha powders and other green tea products.
Lower Cholesterol with Green Tea
March 21, 2024
Drinking green tea can lower cholesterol or triglyceride levels, as was recently shown. See the details in the What It Does section of our Green Tea Review, which includes our Top Picks for green tea.
Green Tea & Blood Sugar
March 12, 2024
Does green tea reduce fasting blood sugar levels? See what a recent study showed in the Blood Sugar Control/Diabetes section of our Green Tea Review, which includes our Top Picks for green tea.
Matcha Green Tea
February 27, 2024
We recently announced our Top Pick for "ceremonial" matcha in our Green Tea Review. A CL member asked if we’ve tested "culinary matcha." Although we did not this year, we did in 2021 and we have added those results to the current report.
Forever Chemicals in Tea?
February 21, 2024
A recently published study found an association between intake of "unsweetened" tea and higher blood levels of PFAS ("forever chemicals"). Should you be concerned? See the details in the Concerns and Cautions section of our Green Tea Review, which includes our recent Top Picks among products.
Also find out if "plant-based" plastic tea bags may be less likely to release microplastics than regular plastic or nylon tea bags.
A new video explaining how to choose the best green tea is also now available.
Also find out if "plant-based" plastic tea bags may be less likely to release microplastics than regular plastic or nylon tea bags.
A new video explaining how to choose the best green tea is also now available.
Green Tea Interaction With Medicine
January 26, 2024
Drinking green tea may significantly affect blood levels of a common beta-blocker, as well as statins, blood-thinners, and thyroid medication. Be aware of these interactions. See the Concerns and Cautions section of our Green Tea Review.
Green Tea for Blood Cancer?
November 21, 2023
Does supplementing with green tea improve biomarkers in patients with leukemia, lymphomas or other blood cancers? Find out what research has shown in the Cancer Treatment section of our Green Tea Supplements Review, which includes our Top Picks for brewable tea and green tea supplements.
Green Tea for Cold Sores?
September 12, 2023
Does green tea help prevent or treat cold sores? Find out what research suggests in our Green Tea Review, which includes our Top Picks for green tea.
Also see: Can any vitamins or minerals help prevent or reduce canker sores or cold sores?
Green Tea Interactions
September 01, 2023
Drinking green tea can affect the absorption of many drugs, as was most recently shown with raloxifene (Evista), a medication used to treat osteoporosis and reduce breast cancer risk. Learn about these interactions (including those with certain statins, beta-blockers, and blood thinners) in the Concerns and Cautions section of our Green Tea Review. Also see our Top Picks among green tea products.
Green Tea and Blood Sugar
August 22, 2023
A laboratory study showed how green tea might help control blood sugar. Get the details in the Blood Sugar Control/Diabetes section of our Green Tea Review, which includes our Top Picks for green tea.
Also see: Which supplements and foods can help lower or control blood sugar?
Chemical Solvents in Tea?
August 04, 2023
Are chemical solvents used to decaffeinate green tea? Find out in our Green Tea Review, which includes our Top Picks for green tea. Also learn about solvents in coffee.
Green Tea for Fibroids?
July 25, 2023
A preliminary clinical study showed that EGCG from green tea extract may help shrink uterine fibroids. New research suggests why. For details, see the Fibroids section of our Green Tea Supplements Review. Also see our Top Picks among green tea supplements and teas and find out how much EGCG they contain.
Are Plastic Tea Bags Okay?
March 14, 2023
Are plastic (nylon) tea bags okay to use? There are two potential problems, as we explain in the ConsumerTips section of our Green Tea Review. Also see our Top Picks for green tea.
Green Tea: More EGCG and Less Caffeine?
February 14, 2023
A CL member asked how steeping green tea in cold water rather than brewing in hot water affects levels of polyphenols and caffeine in the tea. See what a study found in the ConsumerTips section of our Green Tea Review, which includes our Top Picks for green tea.
Green Tea & Heart Disease
February 03, 2023
Find out how many cups of green tea per day is associated with lower risk of heart disease in the What It Does section of our Green Tea Supplements Review, and see our Top Picks for green tea.
Black Tea for Heart Health?
September 02, 2022
Drinking green tea has been linked with reduced risk of death due to heart disease, but how about black tea? See what a recent study found in the Cardiovascular Disease section of our Green Tea Supplements and Drinks Review.
Green Tea for Memory?
September 28, 2020
Can a green tea extract supplement improve memory or cognitive function in healthy, older men and women? Find out what a recent study showed in the What It Does section of our Green Tea Review. Also see our Top Picks for green tea supplements and drinks.
Is Expired Green Tea Safe?
August 26, 2020
We were asked if it is safe to use green tea past its "best by" date and if its flavor or health benefits would be diminished. See our answer in the How to Use section of our Green Tea Review. Also see our Top Picks for green tea — including tea bags, loose tea, matcha, and green tea supplements.
Getting the Most from Green Tea
June 29, 2020
Our Green Tea Review shows that matcha green tea provides higher amounts of healthful catechins than regular green tea. This week, we added information about why this is as well as the results of a new study showing which type of matcha provides the highest levels of polyphenols (i.e., catechins). For details see the What to Consider When Buying section of the review. Also see our Top Picks among green tea products.
Staying Safe With Green Tea
March 09, 2020
If you use a green tea extract (alone or as part of a supplement formula), it is important to take it with food according to several reports, as explained in the Concerns and Cautions section of the Green Tea Review. Also see our Top Picks for green tea in bags, loose, as matcha powder, and in other forms.
Tea & Heart Disease
January 13, 2020
Another study shows that people who drink tea are less likely to suffer from cardiovascular disease. Find out how much and what type of tea was associated with benefits in the Cardiovascular disease section of the Green Tea Review. Also see our Top Picks for green tea.
Green Tea and Breast Cancer Risk
December 16, 2019
Is there a relationship between green tea consumption and breast cancer risk? Learn what a large recent study showed in the Cancer Prevention section of the Green Tea Review. Also see our Top Picks for green tea -- including brewable green tea (from bags and loose tea) and green tea drinks.
Green Tea & Stroke
November 11, 2019
Studies have found green tea consumption to be associated with a decreased risk of stroke. However, a recent study found this to be the case for only for one gender. For details, see the What It Does section of the Green Tea Review. Also see our Top Picks for green tea.
Microplastics in Tea
September 30, 2019
Does Green Tea Prevent Cognitive Decline?
September 23, 2019
Does drinking green tea reduce the risk of cognitive decline and, if so, how much do you have to drink? A multi-year study addressed this question. See the results in the Memory and Cognition section of the Green Tea Review. Also see our Top Picks for green tea.
Green Tea and Blood Sugar
August 16, 2019
Can drinking green tea reduce the rise in blood sugar after a meal, and if so, is the effect greater in the morning or evening? See what a new study found in the What It Does section of the Green Tea Review. Also see our tests and Top Picks among green tea supplements, and brewable and bottled teas.
No Ginseng In Ginseng Tea?
April 26, 2019
A popular maker of bottled teas is being sued for allegedly not putting ginseng in its ginseng green tea. For details, see the Quality Concerns section of the Ginseng Supplements Review. Also see which ginseng products were Approved by ConsumerLab (and see our tests of various Green Teas).
Green Tea and Breast Cancer
April 01, 2019
Drinking green tea has been associated with a reduced risk of breast cancer recurrence. But what effect does high-dose green tea extract have? See what a major study found in the What It Does section of the Green Tea Review. Also see our Top Picks among green tea products.
Green Tea for Lowering Blood Pressure
March 29, 2019
Drinking green tea can help lower high blood pressure — and even reverse ventricular hypertrophy, according to a new study. For details, including the amount and brand of tea used, see the What It Does section of the Green Tea Review. Also see our Top Picks for green tea.
Hot Tea & Cancer
March 19, 2019
Drinking very hot tea increases the risk of developing esophageal cancer. How long should you wait after brewing to drink tea? Find out what recent studies are showing in the What It Does section of the Green Tea Review. Also see other tips for the best way to prepare brewable green tea, and our Top Picks among green tea products.
Getting the Most from Green Tea
January 29, 2019
If you drink green tea to get beneficial compounds like EGCG, learn about a recent study that suggests that the type of water you use to brew tea drastically affects the amount of EGCG you get. Get the details in the How to Take section of the Green Tea Review. Also see our Top Picks for green tea.
Cleaner Green Tea
October 26, 2018
A recent study found that it is possible to modestly reduce pesticides in green tea by following a certain procedure before brewing. For details, see the How to Take section of the Green Tea Review. (Also see our Top Picks among green teas, matcha powders, and supplements.)
A Caution With Green Tea
October 15, 2018
Although consumption of green tea is generally associated with a reduced risk of cancers, drinking it a certain way may increase the risk of certain cancers. Get the details in the Cancer Prevention section of the Green Tea Review. (Also see our Top Picks among green tea in bags, bottles, supplements, and matcha.)
Green Tea as a Prebiotic
July 19, 2018
Green tea may have a prebiotic effect — stimulating the growth of beneficial bacteria in the gut. Find out what clinical trials are showing in the What It Does section of the Green Tea Review. (Also see our Top Picks among green tea products).
Avoiding Green Tea Toxicity
April 23, 2018
The European counterpart to the FDA recently issued its conclusions regarding toxicity from green tea catechins. Get the details in the Concerns and Cautions section of the Green Tea Review.
Green Tea and Ovarian Cancer
March 26, 2018
Drinking green tea was associated with a reduced risk of developing ovarian cancer in a recent analysis. Get the details about this and green tea's relationship to other types of cancer in the What It Does section of the Green Tea Review. (Also see our test results for various types of green tea, including matcha, bagged tea, loose tea, and supplements.)
Statins and Green Tea
March 06, 2018
If you take a statin drug to lower your cholesterol, be aware that green tea can moderately affect blood levels of certain statins, as noted in a recent report. This effect also depends on the amount of green tea consumed and individual variability. For details see the Concerns and Cautions section of the Green Tea Review.
Matcha Green Tea for Memory & Cognition?
February 26, 2018
Can drinking matcha green tea enhance memory or have other cognitive benefits? Find out what a recent study showed in the Memory and Cognition section of the Green Tea Review.
How Hot Should Green Tea Be?
November 24, 2017
Drinking green tea may reduce the risk of certain cancers, but its effect on gastric (stomach) cancer may depend on the temperature at which you drink it, according to a new study. Find out what the best temperature seems to be in the "What It Does" section of the Green Tea Review >> (Also see how brands of green tea, including matcha, stack up in our tests.)
How Much Tea Is Safe?
November 13, 2017
Green and black teas contain fluoride, which helps build teeth and bones, but excessive intake of teas can cause teeth and bones to become brittle ("fluorosis"). How many cups of tea are safe? Find out now based on recent tests of fluoride in green, black, and herbal teas in the "Concerns and Cautions" section of the Green Tea Review >>
Green Tea & Prostate Cancer
October 05, 2017
A recent study investigated the effects of green tea extract in men with pre-cancerous changes of the prostate. Find out if it helped in the "What It Does" section of the Green Tea Supplements and Drinks Review >>
Tea Drinking Associated with Less Cognitive Decline
March 17, 2017
A new study found tea drinkers to have significantly less cognitive decline than others. Read the details in the "What It Does" section of the Green Tea Supplements Review (which includes our tests of teas) >>
Colon Polyps and Green Tea
February 06, 2017
A study of middle-aged men and women found that those given green tea extract after colon polyp removal were much less likely to develop additional polyps than those who did not take the extract. For details about the extract and dose, see the "What It Does" section of the Green Tea Supplements Review (which includes our tests of supplements and teas) >>
Lower Risk of Death With Green Tea
July 05, 2016
A long-term study of men in China found that those who regularly drank green tea — particularly larger amounts — were less likely to die during the study and had lower risks of dying from cardiovascular disease or cancer, compared to non-green tea drinkers. Get the details in the "What It Does" section of the Green Tea Review >>
Green Tea & Cognition
June 17, 2016
Green tea consumption has been associated with a lower prevalence of cognitive impairment in older adults. However, a recent study evaluating the effects of a green tea powder on older adults with Alzheimer's disease and other forms of dementia failed to show a benefit. For more information, see the "What It Does" section of the Green Tea Review >>
Don't Take Green Tea With Iron?
March 15, 2016
A study shows that iron can bind to a key flavanol (EGCG) in green tea, causing it to lose its anti-oxidant activity. Should you avoid iron-containing foods when using green tea? Find out in the "What to Consider When Using" section of the Green Tea Supplements and Teas Review >>
Are Green Tea Pills Safe?
August 24, 2015
Studies have suggested that extracts of green tea can reduce the risk of certain cancers, improve memory, shrink uterine fibroids, and even help with weight reduction. However, liver toxicity has been a concern with green tea extracts. A large, government-funded study recently found that pills of green tea extract can be safe for many people, but some may experience adverse reactions, including elevated liver enzymes. Get the details in the "Concerns and Cautions" section of the Green Tea Review, along with information about what green tea does and our tests of green tea extracts, brewable teas, and beverages >>
Green Tea May Inhibit Starch Absorption
August 08, 2015
A study recently found that taking a green tea extract along with a starchy meal (corn flakes) significantly reduced carbohydrate absorption. This may help explain why green tea may help modestly with weight management. Details about this study, including dosage, along with our tests of green tea supplements and teas, are found in the Green Tea Review »
Green Tea for Weight Management?
July 10, 2015
Green tea has been touted for weight management, but a recent study with a green tea extract casts doubt. More details are found in the "What It Does" section of the Green Tea Review >>
Green Tea for Weight Control?
June 02, 2015
Many studies have looked at whether green tea can help with weight management. The results have been mixed. A recently published study used a high-dose green tea extract. Although the researchers concluded it worked, a closer look suggests otherwise, and points to a potential risk. For details, as well as the results of our tests of green tea supplements, beverages, and brewable green tea, see the Green Tea Review >>
Green Tea Extract and Prostate Cancer
April 21, 2015
A new study, funded by the National Institutes of Health, showed that fewer men with pre-cancerous lesions developed prostate cancer if given a daily green tea extract supplement, although the results were not statistically significant due, in part, to the small size of the study. However, a somewhat similar study found a significant benefit. Learn more about these studies, and see our test results for green tea supplements, teas, and drinks, in the Green Tea Review >>
Another Use for Green Tea?
January 15, 2015
A recently published study found that rinsing with green tea reduced plaque-forming bacteria in the mouth just as well as a prescription mouthwash. Get the details, including the form and dose of green tea used, in the Green Tea Supplements, Drinks and Brewable Teas Review >>
Green Tea and Liver Toxicity
June 19, 2014
Green tea extract was listed as one of the most common dietary supplements linked to liver injury in a newly published guideline for diagnosing and treating drug-induced liver injury. Find out what one of the authors of the guideline had to say about the catechin content of some green tea supplements, and get our test results showing the amounts of catechins in green tea supplements in the Green Tea Supplements, Drinks and Brewable Teas Review >>
Does Green Tea Really Help With Weight?
June 17, 2014
A new study found that a popular green tea extract did not cause a reduction in weight compared to placebo, despite the fact that some previous studies have shown a benefit. Get more details, including which green tea extract was used, in the update to the Green Tea Supplements, Drinks and Teas Review >>
Does Green Tea Improve Memory?
April 12, 2014
This week, news sources reported that a study found green tea helps working memory. While green tea may have benefits, a closer look at this study suggests the news was exaggerated and misleading. For details about the study (and information about other effects of green tea and our tests of green tea supplements, teas, and drinks) see the update in the Green Tea Supplements, Drinks and Teas Review >>
Green Tea "Blocks" Beta-Blocker
January 17, 2014
A new study shows that drinking green tea can drastically reduce the amount of a beta-blocker (nadolol, Corgard) absorbed into the bloodstream. Beta-blockers are typically taken to lower blood pressure, raising concern for people using green tea along with this beta-blocker and, possibly, related medications. Get the details, along with our tests of green tea drinks and supplements, in the update to the Green Tea Review >>
If you take a beta-blocker (which includes the popular drugs metoprolol (Lopressor, Toprol) and propranolol (Inderal)), be aware that chromium and CoQ10 may offer benefits.
If you take a beta-blocker (which includes the popular drugs metoprolol (Lopressor, Toprol) and propranolol (Inderal)), be aware that chromium and CoQ10 may offer benefits.
Liver Toxicity with Supplements, Including Green Tea
December 22, 2013
An increase in cases of liver toxicity associated with dietary supplement use has recently been reported. In an article about the findings, The New York Times reports that bodybuilding supplements and products containing green tea extracts are among those associated with such cases. For more information about green tea extracts and toxicity, see the Concerns and Cautions section of the Green Tea Supplements Review >>
Green Tea to Treat Fibroids
September 27, 2013
A new study suggests that green tea extract may help shrink uterine fibroids (common in women of childbearing age) and reduce symptoms. For details, as well as test results and comparisons of green tea extracts and brewable teas and drinks, see the updated Green Tea Review >>
Don't Drink Too Much Tea!
June 01, 2013
After publication of our Green Tea Review last month, a CL member emailed us about the potential danger of getting too much fluoride from tea. Although this won't happen from just a few cups of tea daily, there have been recent cases where habitually drinking extremely large amounts of tea has caused "fluorosis" causing bone pain and even tooth loss. See the warning (and our tests of green tea products) in the updated Green Tea Review >>
