Cold-Steeping Green Tea

Cold-Steeping Green Tea
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Surprising new data on what may be the healthiest way to prepare tea.

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What’s the healthiest way to prepare green tea? Recently, in Taiwan, a new trend has arisen of cold-steeping tea. Not like iced tea, where you make it hot, then cool it down. But you start with cold water, throw the tea in, put it in the fridge for two hours, or just leave it at room temp.

Supposed to have less caffeine, reduced bitterness. And I’m sure it does; but cold water probably also doesn’t draw out many of the antioxidants, either. I mean, that’s the whole point of brewing tea with hot water, right? To extract all the nutrition. We shouldn’t just presume, though, and so scientists in Italy took it upon themselves to compare the antioxidant activity of hot- versus cold-steeped tea.

Here’s the data for hot tea. This is measuring the lag time before cholesterol oxidizes. You mix LDL—bad cholesterol—with an oxidizing agent, like copper in this case, and it takes about 28 minutes to oxidize. But you add tea, and the oxidants slow down the oxidation and increase the lag time. That’s a good thing. And, as you can see, oolong tea is better than black; green is better than oolong; and white is the best overall.

But this is the antioxidant activity for hot brewed tea. In a surprise upset, cold-steeped tea was even better. Significantly better. So much so that cold-steeped black may even be healthier than hot-brewed white.

Why? Well, the only thing they could think of is that hot water is so hot that it destroys some of the catechins, the antioxidants in tea. So, I no longer brew my tea; I just throw it in cold water. Saves time, saves energy, and we now know it’s even healthier!

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

Please consider volunteering to help out on the site.

Image thanks to Brandon Heyer via Flickr

What’s the healthiest way to prepare green tea? Recently, in Taiwan, a new trend has arisen of cold-steeping tea. Not like iced tea, where you make it hot, then cool it down. But you start with cold water, throw the tea in, put it in the fridge for two hours, or just leave it at room temp.

Supposed to have less caffeine, reduced bitterness. And I’m sure it does; but cold water probably also doesn’t draw out many of the antioxidants, either. I mean, that’s the whole point of brewing tea with hot water, right? To extract all the nutrition. We shouldn’t just presume, though, and so scientists in Italy took it upon themselves to compare the antioxidant activity of hot- versus cold-steeped tea.

Here’s the data for hot tea. This is measuring the lag time before cholesterol oxidizes. You mix LDL—bad cholesterol—with an oxidizing agent, like copper in this case, and it takes about 28 minutes to oxidize. But you add tea, and the oxidants slow down the oxidation and increase the lag time. That’s a good thing. And, as you can see, oolong tea is better than black; green is better than oolong; and white is the best overall.

But this is the antioxidant activity for hot brewed tea. In a surprise upset, cold-steeped tea was even better. Significantly better. So much so that cold-steeped black may even be healthier than hot-brewed white.

Why? Well, the only thing they could think of is that hot water is so hot that it destroys some of the catechins, the antioxidants in tea. So, I no longer brew my tea; I just throw it in cold water. Saves time, saves energy, and we now know it’s even healthier!

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by veganmontreal.

Please consider volunteering to help out on the site.

Image thanks to Brandon Heyer via Flickr

Doctor's Note

Check out these videos for more on green tea:
Cancer, Interrupted: Green Tea
Better Than Green Tea?
Antimutagenic Activity of Green Versus White Tea
Why Do Asian Women Have Less Breast Cancer?

And check out my other videos on green tea

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

If you haven’t yet, you can subscribe to my videos for free by clicking here.

71 responses to “Cold-Steeping Green Tea

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  1. 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?

    1. 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 :)

    2. 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.

  2. 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?

  3. 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?

    1. Since your tea purchase was recent, you can’t be sure if it was harvested prior to, or post Fukushima. Erring on the side of caution is not bad, especially when we’re trying to minimize our exposure to contaminants, (see, for example, http://nutritionfacts.org/video/mercury-in-vaccinations-vs-tuna-2/. Purchasing white tea from the Darjeeling region of India or Ceylon, Sri Lanka are also great choices. Check out: http://nutritionfacts.org/video/dietary-brain-wave-alteration/, to see how tea effects the brain, and: http://nutritionfacts.org/videos/green-tea-vs-white/, to learn more about the benefits of white tea and how you can enhance them.

  4. 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.

    1. 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

    2. 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.

  5. 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?

    1. I agree – the only difference appears to be the size of the error bars! It looks like green tea is the ONLY tea that cold steeping doesn’t improve it’s antioxidant properties! Why does the video appear to focus on the ONE tea where there is no difference!? Weird.

  6. 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. 

    1. 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 :)

  7. 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

  8. 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?

  9. 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!

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

  11. 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.

  12. 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.

  13. 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!

  14. 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

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

  16. 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!

    1. 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!

  17. 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.

  18. 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.

  19. 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.

  20. 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.

    1. according to the graph in the video, green tea had the same amount of antioxidants, whether hot brewed or cold steeped. Meaning, cold steeping did not increase antioxidants in green tea.. only the other teas.

  21. I would like to know if I bring my tea to hot, not boil, and then put my bags in ( black ,green, and white) will I still be able to draw the catechins out. I believe you would. Also, I usually steep my tea for 20 min on average.

  22. It seems then that cold brewing is healthier than hot brewing. However, in this video it’s said the more we (hot) brew white tea the better for DNA protection. I am confused…

  23. As much as I love the work here at NutritionFacts.org, in all fairness, I think the conclusions here are incorrect, or at least incomplete. I pulled and read the full paper. The authors used 7 different assays to compare various aspects of hot vs. cold brewed teas. (hot brewed at 90º C for 7 minutes, cold brewed at room temperature for 2 hours). The LDL assay shown in Dr. Greger’s video uses a method that tests lipid oxidation. It is true that cold white tea had more antioxidant capacity in this assay, but there was no difference (no statistical significance) for green, oolong, or black. Furthermore, in the other 6 assays (present in the full paper but not extracted for this video summary) results tended to show no difference between or hot and cold, or favored hot-brewed. The exception was white tea, which tended to show better results cold-brewed in several (but not all) of the assays. For those interested, the other 6 assays were: 1. Measure of total phenol content (more in hot for green tea, more in cold for white tea, not statistically significant in oolong or black); 2. Metal-chelating activity (more in hot for white and oolong, not statistically significant for green or black); 3./4. Antioxidant activity using two different non-LDL assays (more in hot for oolong, more in cold for white, not statistically significant for green and black); 5./6. Antioxidant activity using 2 different LDL assays measuring protein (rather than lipid) oxidation (no statistically significant difference across the board, with the exception of more activity for cold-brewed white in one of the 2 assays). What I take from this is that the results are mixed. More important than any small differences between hot- and cold-brewed teas is the fact that BOTH hot and cold brewing methods were able to extract polyphenols and antioxidant compounds. My personal takeaway message is going to be that you can get benefits from tea with either brewing method – brew it how you like it!

  24. I like hot tea though sometimes. Usually I prefer iced tea but I love hot matcha and green tea. However I actually thought of this a long time ago which is why I never make the water boiling or too hot.

  25. But did they correct for the significantly longer duration of cold brewing? Typically, when you brew hot tea, you pour the hot water in, steep it for a few minutes and drink. When you cold-brew tea though, the tea sits in the water for hours. Sometimes up to 24 hours. I imagine that if you used hot water, and then let the tea steep for hours upon hours, the results of cold vs hot would equalize.

    In other words, it’s probably not the temperature of the water that matters, but the duration of the steeping. More steeping time = more diffusion.

    1. Makes one wonder if one could achieve the best of both by first steeping the tea hot, to get that initial burst of diffusion, and then letting it steep over the next couple hours to get the perks of a long steeping time. Given that there are three things that improve diffusion (high temperature, duration, and movement), seems reasonable that 2 out of 3 is better than 1 out of 3.

      Cheers :)

  26. Question: Ok so I’ve been dumping a couple tablespoons of macha green tea into an pitcher and letting it soak overnight in cold water. I drink this tea the next day but the powder it self sits at the bottom of the container and I drink the green water. In the past I would brew it hot and mix the tea powder into the drink itself. With macha tea am i suppose to drink the powder as they do traditionally or is leaving the ground tea leaves at the bottom just fine? Side note I do get an upset stomach very quickly if I drink the macha leaves instead of leaving them at the bottom of the bottle. This also happens when I drink just one cup. Ami losing health benefits and wasting precious macha powder if I drink it cold brew style and later pour out the powder at the bottom? I also tried putting the powder into my smoothies in the blender and I also get sick to my stomach that way too. any advice I really don;t want to waste macha as it is so expensive

  27. Like others above have said, I enjoy hot – or at least warm tea. I always heated a cup of water for 2 min. in microwave, then added the bag. I’m thinking now, will heat it only for 1 min. Maybe will be a little healthier.

  28. I like both hot and cold tea, but isn’t hot-brewing (at or near boiling) safer in case the tea has any bacterial contaminants?

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