Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on green tea. Also, there are 1,686 other subjects covered in the rest of my videos--please feel free to explore them as well!

For more context, check out my associated blog posts: Is Caffeinated Tea Really Dehydrating?Hibiscus tea: flower powerNutritionFacts.org: the first month, and Why Less Breast Cancer in Asia?

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  • http://www.facebook.com/profile.php?id=676800493 Benjamin Stone

    A great way to enjoy green tea on a hot summer day – glad to know the health benefits are enhanced cold steeped! Does this also apply to matcha green tea powder in cold water mixed vs steeped in hot water?

    • Michael Greger M.D.

      With matcha we presumably don’t care about how much of the nutrition dissolves into the water, because we drink it all up, so I’d suggest mixing it up any way you like! (I put mine in smoothies :)

    • C.Jones

      matcha is healthy and good any way. but unless you mix properly, it can get clumpy. personally though, I think the simplicity of throwing it in with some ice and cold water is much simpler than mixing with hot then adding to ice.

  • Toxins

    So you have to leave it for 2 hours for it to have more anti oxidant content then hot tea? Ive been drinking your “healthiest drink”…chai tea with raw cacao powder. Is this best served cold?

  • minetti

    Do you feel there is a concern with radioactive tea coming from Japan? France just refused to accept a shipment of Japanese tea, due to high radioactive cesium levels. I recently purchased some from Costco, that I am not going to drink. I have instead, ordered some from India. What are your thoughts?

  • ks391262

    Anyone know where I could buy some matcha tea? What stores sell it?

  • Carojo95

    I wonder if you gently warm it after cold brewing will you destroy the cold-brew effects. I just like warm tea!

  • KJR

    I recently heard an interview with Dr. Klaper in which he states that tea contains antimicrobial properties that destroy the gut flora, so tea should not be consumed. Always believing that green tea was good for us, I’m confused and would love some clarification. Thank you.

    • C.Jones

      after doing some research ive found the very opposite is true…yes there are some antimicrobial effects, but in a good way, meanwhile green tea, like matcha, which has natural antibiotics can actually improve gut flora

    • Non-compliant

      Watch
      out for this green tea! Talking from experience! It will make you
      hyperactive, with resulting speeding, lowering self control etc, and
      also, I followed this for months while one morning was dizzy like a
      drunkard, asked fellow lifeguard, and he said he experienced the same
      and told me that is due with the interference with the gall.

  • Jacci

    Although the graphs show the other teas significantly higher when steeped cold, green tea appears on the graph at the same level whether hot or cold. Is this an error?

    • http://www.eatandbeatcancer.com/ Harriet Sugar Miller

      Could somebody respond to this? Green tea appears to be the same on the graph whether it’s brewed hot or cold. Are we missing something?

      • Chuck V

        I agree – even with the error bars, the result appears rather odd. But no comments as to cause

        • Tommasina

          Good question! I’m intrigued as well.

  • Padraig

    I always use the coffee maker to get water for my green teabags. This is both easier and prevents water that’s too hot from scalding the tea. 

    But wake up! The human body is 37 degrees celsius. If you put it in lower than that it will just heat up in your body anyway. 

    • brjarrard

      Unfortunately, most coffee makers have plastics in contact with water in both the reservoir and brewing/heating process. Unless you are using a stainless “percolator” style pot you are ingesting toxins leached from the heated plastics.
      “But wake up…” does not warrant attempt at rebuttal :)

  • se34

    Dr. Greger,

    What’s the latest on epicatechin and/or raw cocoa? I noticed that the researcher, Norm (Norman) Hollenberg (sp?) is quoted as saying something to the effect that epicatechin should be “reclassified as a vitamin” – and that many diseases may one day be seen as related to “epicatechin deficiency.” Would be very intrigued to know your take on this. (Thus far, I’ve reluctantly begun a rigorous twice daily dose of a heaping Tablespoon of Raw Cocoa Powder added to various things; tough work, but someone has to do it. :)

    Thanks,
    Steve

  • se34

    Relating to this video (and epicatechin): I also sometimes enjoy a nice cold cup of cat’s claw infusion (sweetened with healthful, natural things). I’ve heard that cat’s claw and cocoa – both raw (as the heat zaps it) – are some of the best sources of epicatechin?

  • http://www.facebook.com/alexandre.amirizian Alexandre Amirizian

    I use my yuzamashi (water cooler) before I brew it! Japanese tea is traditionally steeped with water ranging from 60-80 deg Celsius! Gyokuro being the finest tea and usually made with water after it just has stopped steaming!

  • Deb California

    Hi! I drink decaffeinated green tea daily (water-processed). Have the catechins already been destroyed in the decaffeinating process?

  • Ilana

    Does this also apply to hibiscus? Is it better to cold brew hibiscus too?

  • Bee Healthy

    I like my tea hot most mornings, but not scalding hot. I have to wait 5 to 10 minutes after brewing for tea to cool to a drinkable temperature. If we were to brew tea just slightly hotter than we like to drink it, how long would we have to brew it for? Maybe I can just tell from the taste? As it becomes bitter when over-steeped.

  • painterguy

    I cold steep Zinger Wildberry (hibiscus) tea. There is some in the frig at all times. I still like my green tea very warm–like my coffee. The warmth is soothing on my throat and senses. My coffee comes from a coffee pot, which doesn’t get very hot. I put my green tea bag in a jelly jar full of water and put it in the micro for two minutes. I could cut that to one minute and still have soothing, warm tea.

  • Diana

    I’ve been drinking my green tea steeped in room temperature water or cold water for over 5 years now!! I wasn’t thinking about the health benefits… It was just easy to drink this way as I dont enjoy hot drinks! When people asked me why I do what I do!! I jokingly made up something saying “Hot water kills antioxidants, so I drink my tea this way because its more healthier!” Lol!! I never thought my joke would be an actual fact!

    • Sebastian Tristan

      Can you next joke by saying that eating medjool dates all day long is the healthiest thing ever? =D

    • Arjan den Hollander.

      Don’t forget the lemon.

  • Denis Spasyuk

    all energy companies hate this website :)

  • preethi

    My skin has become dark after consuming green tea for a long period of time. I want to know when I can drink water so that I get the benefits of green tea and at the same time do not become dark

  • Sebastian Tristan

    Very interesting. But what about decaffeination? I often decaffeinate tea by throwing out the first infusion. Does the first cold-steep decaffeinate tea?

  • DL Stephens

    Hey there, Doc! Radishes did great in my garden (Jan, Feb, Mar), this year; been eating their “greens” day-in-day-out, raw & cooked, in my march towards a complete plant based diet. Curious, tho, how do they rate, say compared to kale? Hope to donate soon…I’m unemployed… Thanks, Sir!

    • Thea

      DL Stephens: I don’t have an answer to your question, but I wanted to congratulate you on your, “march towards a complete plant based diet.” It sounds like you are doing great. I wish you luck on both your diet and getting a job!

  • http://bebrainfit.com/ Deane Alban

    I’ve been cold brewing green tea for years. I had heard somewhere along the line that cold brewing left more beneficial compounds because heat destroyed some of them. I was happy to find this video to clarify this. Here’s how I make it – it always comes out perfectly. Never bitter. http://bebrainfit.com/lifestyle/nutrition/6-ways-green-tea-benefits-your-brain-plus-my-secret-recipe/

  • Jessica

    Thank you for posting the transcript too.

  • Rodica Atzberger

    Sorry, where from the copper? From the teapot?
    And, I wonder if the conventional (even organic) tea contains some trace metals or toxins? Thank you.

  • panopticon1984

    This raises many questions. Traditionally, green tea is prepared with water that is hot, but cooler than that used to prepare black tea. It would be nice to know what the outcome would be at various temperatures.

  • joe

    anti oxidant have been link to shorter life span in lab animals…..

    • Victoria

      Where?

  • Nicole Furlan

    So interesting! Is there any data showing the differences in caffiene content between hot and cold brewed tea?

  • Here

    I wonder if these results were accurate. There are two big problems. First, people often overheat tea. Most tea is NOT boiled, with significantly cooler temperatures needed to properly steep thr tea. So, did they boil all the tea, and compare overheated tea with cold? Or properly prepare tea at it’s actual cooking temperatures, and compare the correctly prepared tea with cold?

    There is a second, even bigger, problem. They used two hours steeping of a cup, against only one cup of hot tea. That is comparing one apple, with a bag of apples. I may steep a teaspoon of oolong six times before discarding the tea leaves, getting nutrients and sometimes different flavors! Of course a two hour soak will beat ine single steeping! To accurately test cold vs hot, you would need to not test one cup of tea, but how much is ultimately brought out of a gram of tea … at least for oolongs and dark teas.

  • EdK

    I hate to say it, as I really like NFO, but in this case, Dr. Greger jumps to a conclusion by
    extrapolating way beyond the data. Just because cold-brewed teas have higher
    antioxidant activity than hot brewed teas, does not make them better in other
    respects. Green tea has documented effects in preventing cancer, etc. It may
    well end up that the anticancer compounds that prevent cancer may require hot
    water brewing to effectively make it into solution, and that the increased
    antioxidant activity DOES NOT reflect increased amounts of cancer preventative
    compounds. And as far as the data goes, almost all of the data looking at the
    health effect of green tea look at the health effects of people drinking green
    tea steeped in hot water. Compared to hot brewed green tea, the epidemiological
    track record of cold brewed green tea at this point seems almost non-existent.
    One can of course assume that all of the beneficial compounds that give hot
    brewed green tea also end up in cold-brewed tea in the same or higher amounts –
    but to my mind, that seems a pretty big and unlikely assumption. Until someone
    does a comparative analysis of the specific compounds in hot vs. cold brewed
    green tea, with respect to their identities and amounts, I see hot green tea as
    the green tea of choice.

    I note Dr. Greger made the same assumption with respect to antioxidant activity as basically the only
    important thing to look at when he promoted hibiscus tea over green tea, but
    antioxidant activity just seems one factor among many to consider with respect
    to green teas beneficial effects, and once again compared to green teas, but as
    far as I know the epidemiological and other research studies with respect to
    hibiscus tea’s effectiveness as a cancer preventative, seem pretty much unknown.
    Perhaps they exist, perhaps they don’t, but hibiscus tea having a high
    antioxidant activity does not guarantee anything other than that it has a high
    antioxidant activity. Green tea and hibiscus tea seem quite different in their
    chemical composition (compare: http://www.ars-grin.gov/cgi-bin/duke/farmacy2.pl
    with http://www.ars-grin.gov/cgi-bin/duke/farmacy2.pl
    ) Antioxidant activity seems a quite general and non-specific
    measure, INDIVIDUAL compounds, that one tea has but the other one does not – may
    play far more important roles with respect to a teas effects.

    • EdK

      Fo some reason the links I provided don’t work – hopefully this general link will:
      http://www.ars-grin.gov/duke/plants.html
      Just enter the common or scientific name of a plant, choose non-ubiquitous chemicals, an the database will list them.