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CL Answers (21)

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Clinical Updates (10)

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Vitamin C for Colds?

Taking vitamin C may modestly help with colds, according to a new study -- but there's a catch. Find out in the What It Does section of the Vitamin C Supplements Review. (Also see our Top Picks for vitamin C supplements.)

Can Echinacea Prevent Colds?

Although the evidence behind echinacea has been mixed, a new study -- the largest to date -- found that taking a particular type of echinacea supplement throughout cold season reduced cold "events" (catching colds and days spent with colds) by 26%. See the update to the Echinacea Supplements Review for details about this particular supplement, including the special way it is taken. More >>

COVID Transmission Among Vaccinated?

Can you catch COVID from someone who is vaccinated if you are vaccinated? Find out what data suggests in our article about COVID-19 Vaccines.

How Much Tea Is Safe?

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 >>

Is Quercetin Safe?

Quercetin has been proposed as a treatment for a range of medical conditions, including COVID-19, but is it safe? Find out what studies have found, including results of a recent, small clinical trial, in the Concerns and Cautions section of the Quercetin Supplements Review. Also see our Top Picks for quercetin.

Is Expired Green Tea Safe?

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.

Whitener In Many Pills May Not Be Safe

Titanium dioxide, which is commonly used to whiten pills, is not safe according to the European equivalent of the FDA. Find out why in our Review Article about Inactive Ingredients.

Are Green Tea Pills Safe?

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 >>

Flu & COVID Vaccines

Additional research indicates that it's safe to get flu and COVID-19 vaccines together. Get the details.

Natural Toothpastes

Are "natural" toothpastes safe and effective? Find out in our updated article about Finding the Best Toothpaste.