Update on Yerba Maté

Update on Yerba Maté
4.31 (86.25%) 16 votes

Why this herbal tea may increase cancer risk.


Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

And finally, what about yerba maté, a Latin American herbal tea that’s been linked to cancer? Should we continue to avoid it? Yes, an evaluation of the cytotoxic and genotoxic activity of yerba maté on human white blood cells found it caused a significant increase in the rate of cell death. Not what you want from your herbal tea.

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Image thanks to Tracy Ruggles via flickr

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

And finally, what about yerba maté, a Latin American herbal tea that’s been linked to cancer? Should we continue to avoid it? Yes, an evaluation of the cytotoxic and genotoxic activity of yerba maté on human white blood cells found it caused a significant increase in the rate of cell death. Not what you want from your herbal tea.

Please consider volunteering to help out on the site.

Image thanks to Tracy Ruggles via flickr

Doctor's Note

Check out these videos on herbal teas:
Herbal Tea Update: Rooibos & Nettle
Is There Too Much Aluminum in Tea?
How Much Hibiscus Tea is Too Much?
Chamomile Tea May Not Be Safe During Pregnancy
Enhancing Athletic Performance With Peppermint

And check out my other videos on Yerba Maté

For more context, check out my associated blog post: Soy milk: shake it up!

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

44 responses to “Update on Yerba Maté

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  1. But is it bad and have the PAH’s because the Yerba Mate is smoked as part of the “drying” process?? Guayaki says that the Organic, Unsmoked, Air Dried Mate has less Pah’s then Green Tea. I know that they are selling the product, but I also really want to know what in the Mate is bad. For many years I drank the traditional blend, but in the last few years I have switched to Air Dried, Green, Organic Yerba Mate with water that is not terribly hot. And IF it is the “smoking” process that is bad, then are other teas smoked, like Lapsong? And then does it make my beloved Organic, Air Dried, Yerba Mate okay? It’s seriously a major happy tea………Please Miraculous Michael Gregor, do deliver good news to me.

    1. That is an excellent question, and unfortunately the answer is that we just don’t know. A study of 8 different brands found “very high concentrations” of carcinogenic PAHs in all of them. As you’ll see if you have a chance to read it, they even go as far as to say suggest “that the benzo[a]pyrene intake associated with drinking mate may be comparable with that associated with smoking cigarettes.” Yikes! If you are going to drink it I’d recommend unsmoked varieties, but unfortunately we’re not sure how much better they are. I’ll definitely keep my eyes peeled for any new data–I used to love the stuff myself.

      1. This piece of literature, on the other hand, is thought provoking indeed. I am amazed to see the hydrophobics making their greatest impact in the first 5 minute steep, and irrespective of temperature! So my 6g daily Mate is equivalent to 2.7 cigarretes’ worth of benzo- yeesh. I hope the antioxidants have been negating that….

      2. You’re right to claim that there are “high concentrations” in all 8 brands. But there’s a surprisingly wide variation — let’s compare ‘Brand 5’ against ‘Green Tea’.

        When you do so, you’ll see that Brand 5 only has twice the total level of PAHs compared to Green Tea. Moreover, a large number of Brand 5’s PAHs come in the form of Fluoranthene and Pyrene. Fluoranthene is classified by the International Agency on Cancer Research as “not classifiable as to its carcinogenicity to humans”.
        Pyrene is trickier. Maybe it’s bad for the liver and kidney. But the EPA has placed “pyrene in weight-of-evidence group D, not classifiable as to human carcinogenicity.”

        If we are willing to exclude Fluroanthene and Pyrene from our calculations, then Green Tea and Brand 5 are very similar ~330 vs. ~200.

        I’d guess that Brand 5 is an ‘unsmoked’ variety. The evidence here doesn’t seem damning — what do you think?

      3. They don’t seem to be organic, nor do we now anything about the quality of the brands do we?
        Getting a bit tired of studies referred to and then pointed to as facts that aren’t complete at all – If it isn’t studies done with REAL food, organic and good quality or even better Biodynamic I can’t take them seriously, could it not just as well just be the pesticides used in the production of these 8 brands?
        I would love to see you point out such points in your videos when presenting these studies, as you’ve actually looked into them properly, as it seems ever so relevant, and it seems to be it can actually be very misleading to post such videos without such crucial details, as many people wont bother reading the actual study, as your doing it for them(us).
        All the best for all your efforts into wholistic health!

      4. Could it be the gourd costume of drinking out of a metallic straw. We like to brew the unsmoked Yearba Maté in just warm water then pour the tea through a strainer into a regular mug. I’m wandering how could the metal straw be healthy? Maybe that’s why the cancer association?

  2. Yeah!! I know, I read some of that stuff. BUT, nearly all the mate in the world is consumed in South America and basically every brand I have ever seen there is Smoked. I think it isn’t very “porteno” to drink unsmoked. So I am assuming that all the varieties they tested were smoked. Maybe I can find out from Guayaki which study they are talking about. I ran into research on the web somewhere, but you had to pay for the rest of the paper. Yeah, I drink it from the gourd and quit a few times and may still because it does elevate the heart rate. We drink vats (well under the 60 cups a day :) of green tea as well, but I don’t feel complete without my Mate! Thanks for your answer!

  3. Hey Dr. Greger.

    I take Vega Sport pre-workout drink (18g servings) five times a week. For each 18g of serving, there’re 167mg of yerba mate leaf.

    How much of a threat is yerba mate in this form and at the frequency I consume per week? Thanks.

  4. Thanks DrDons for your time and research.

    I can’t imagine too many pre-workout drinks that don’t have carcinogens. I’m curious what Vega has to say about this.

    It’s just that it keeps me jacked and focused during workouts. I definitely will cut down on the consumption, and likely eventually eliminate it for good.

        1. I not sure about the claims either. My family are Argentinian, and we have always drank it for decades now. One thing that make me think otherwise (even though it’s based on a couple people) is my grandparents drink literally all day long and from the gourd which is a much more concentrated form compared to a cup of of steeped Maté. My grandfather is 99 years old, and healthy and strong as an ox. He has never exercised in his life and never really followed any kind of diet. Same goes for my grandma, she’s 95. I know you cant base it on 2 people, but I believe no matter how careful you are in life, something is going to eventually get you. I think that the benefits of Mate highly outweigh the negatives, especially when your old and eating becomes less attractive, the 24 vitamins and minerals, 15 amino acids, and munerous antioxidants can prove be an excellent supplement to your diet. If we refrained from anything that was potentially harmful to us, we would basically live on a diet of water and a select few other fruits and vegetables. Ev en with a healthy diet, there are countless other things we could be diagnosed with in life. So I say if its healthy for the most part, enjoy it! Because life is too short, and we cannot protect ourselves from everything that’s out there. We do the best we can, and try to enjoy life along the way. There are much more harmful things we could be doing, so enjoy your Mate and hope for the best.

          1. absolutely! my feeling too. I was introduced to Mate a decade ago by a friend of Argentinian descent. It’s been a part of my life ever since. I drink at least to liters a day!!

  5. Hello Dr. Greger. The primary lit you quote in the video (Evaluation of the cyto- and genotoxic activity of yerba mate (Ilex paraguariensis) in human lymphocytes in vitro) is highly misleading, and using its results to validate the potential carcinogenecity of Y. Mate demonstrates poor interpretation of the data. The authors utilized caffeine as a control, and found it to perform worse than Y. Mate extract in the two ‘genotoxic’ assays of micro nuclear formation and aneugenic activity. Aside from yielding a non-result, the experimental design was flawed, as the Mate liquer produced was 4-8 times the strength of Mate produced in a normal kitchen (1-2 Tbsp per 8 oz cup yields 25.4-50.8g per Liter; compared to the 200g per Liter used in the experiment.). Couple this with the fact that the brewing method favors the extraction of more lipophilic molecules than would be encountered in normal brewing, (212 deg for 10 min vs 150 deg for 5-8 min) and the whole study is shot due to improper methods before we even get to discussing controls. Finally, the in vivo equivalent of bathing cells i

    1. Old post i know, but there was a time when many supplements were claiming to “kill the AIDS virus in a petri dish.” Well, the FDA (not the most objective source it’s true) in order to get all of these fake AIDS cure off the market, showed how warm water kills the AIDS virus in a petri dish. A petri dish is not the human body!

      1. My friwnd worked at a kidney dialysis lab and he said Aids/HIV in blood when spilled on the floor dies immediately. They only thing they had to worry about was hepatitis. Your right its not the body, which is a breeding ground for the virus. Viruses need a perfect environment to live and thive.

  6. Yerba mate triggered my anxiety attacks I developed a week after taking it. Mate contains theobromine–a neurotoxin. Stay away as it messed up by adrenal glands.

    1. I do not know ,but, I have heard of more health challenges with coffee. We drink Green Tea daily and have Yerbe Mate as a treat, after hearing about testosterone problems with Stevia , that has me concerned .

  7. It seems to me that the problem with yerba mate is the SMOKING process of drying, rather than the leaves themselves. I hope research comes out soon on the effect of the NON-SMOKED yerba mate varieties. Please keep updating this topic! Thanks.

  8. I’m from south brazil.
    Here we drink it every frakking day.
    Its a tradition and honestly is not because theres a vague relation to cancer we’ll start giving up this tradition.

  9. For someone like myself, whose maternal family is Paraguayan, and drinks it daily, how can I flush my system of these carcinogens? I am 42 years old and thought it was a healthier option. Thank you!

  10. What a reductionist vision. So, all this time.. it wasn’t the agrochemicals, nor the pollution or the synthetic poison added to our food. It was Mate! Thank you “Dr” for helping the sensationalism about health with this 0:30 seg. – explaining nothing – video about an historically used herb.

    1. Goucho: To my knowledge, there is no GMO wheat on the commercial market.

      Now I’m putting my moderator hat on: Please watch the language. This site is a family site.

    1. Andrea: Look just below the video for the “Sources Cited” section. You can click that text to expand the section and see the reference.

  11. Just couple of notes. I’ve noticed how caffeinated hot drinks react with my physiology over the last 5 to 10 years. A cup of coffee at night often resulting in waking with wet shins and a general sweat. Cocoa had a similar reaction but nowhere near to that extent. I still drink the cup of tea, and also note that when I do, it increases the BO from under my arm pits significantly. Be it green tea or black. Herbal teas I have no problem with, except for yerba mate, the potency of my BO level after drinking this forces me to the wash room and also to drink water to help flush it out. The other thing I find with Yerba Mate is that it stains the cup like no other herbal/tea I’ve encountered. Dave explained this was due to the Chlorophyll and Tannins which he says is not unusual. Dave also cites an article and video of his that considers the Yerba Mate and Cancer issue: https://www.youtube.com/watch?v=27Pom5vnb58&lc=z13gjrz45xn4dpv5c04chdtztkz4wj2gcxo0k – Please let me know your thoughts anyone. I wonder for example to what extent the study of 8 brands of Yerba rules out the confounding variables of smoking, alcohol consumption, drinking it hot, and meat consumption: http://cebp.aacrjournals.org/content/17/5/1262.full.pdf+html – Many thanks

  12. I make ‘tea’ simply with hot water and lemongrass. Is this an issue? What about eating lemongrass? I make my own curry pastes which usually have a fair amount. The lemongrass is from our own garden and all organic.

  13. It is a bummer that the yerba mate used wasn’t Argentine. The samples were Brazilian and there is a great difference between these yerbas. I wonder if another study using Rosa Monte or Taragüi or Piporé (top Argie brands) has been conducted. I personaly dislike the Brazilian ones, their color, flavor, texture is so different from the Argie ones.

  14. Re. yerba mate and cancer.

    The research quoted by Dr Greger in these clips is a decade old!

    While laboratory analysis of several different teas shows that mate has the highest levels of polycyclic aromatic hydrocarbons (PAHs) (followed by black, white and green teas), only trace levels of PAHs were detected in *infusions* of mate tea. Drinking mate tea is therefore unlikely to lead to excessive PAH intake.
    https://www.ncbi.nlm.nih.gov/pubmed/29486662 (2018)

    The risk of cancer has been shown to be increased only in those subjects who drink “very hot” mate, and not when mate is consumed at moderate temperatures. It’s the temperature that does the damage, specifically in the oesophagus, pharynx, larynx, and oral cavity.
    https://www.ncbi.nlm.nih.gov/pubmed/28981366 (2018)
    https://www.ncbi.nlm.nih.gov/pubmed/27318851 (2016)

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