Is yerba mate carcinogenic? We don't believe the rumours!

Every so often, a storm starts on the internet about the alleged carcinogenic effects of yerba mate. The headlines of the articles scream from the screens of our monitors and scare us, and we click on them in horror, reading further revelations. Do we have anything to fear? Is yerba mate really harmful to health?

Summary:

1. Is yerba mate carcinogenic? Facts and myths
2. Latest reports on the carcinogenicity of yerba mate
3. A rash of articles on the alleged harm of yerba mate
4. An alternative for those who still have doubts

Is yerba mate carcinogenic? Facts and myths

Yerba mate contains a large dose of caffeine, due to which some people choose it as an alternative to coffee. In addition to caffeine, it also contains an abundance of vitamins, minerals and other organic compounds that have a positive effect on the functioning of the entire body. We have discussed the properties of yerba mate in more detail in this post on our blog. Just like coffee or tea, yerba mate has its admirers and opponents. However, for many, Ilex pparaguariensis, a yerba mate plant is still a mystery, and if we do not know something, we start to fear the effects and look for the worst. With successive studies of the plant discovered by the Guarani Indians, considerations about the harmfulness of yerba mate began to emerge. From the analysis of scientific publications and information found in various sources describing the topic of yerba mate and cancer, we have concluded that two factors are behind the alleged carcinogenicity of the holly plant: the hot water used to brew the dried mate and polycyclic aromatic hydrocarbons (PAHs) – the harmful substances that are formed by the incomplete combustion of organic matter found, among other things, in heat-treated food products.

First studies and publications

The first serious reports that yerba mate may be carcinogenic appeared already 30 years ago. One of the first researchers on the subject was Eduardo De Stefani, who, together with his team, conducted dozens of studies on the link between yerba mate and cancer between 1990 and 2004, involving more than 13,000 patients. One of the most famous studies was conducted in 1996 on a group of about 1,000 Uruguayan adults, which found that yerba mate drinkers had a higher risk of cancer by up to 60%. In 1991, there was a monograph published by the International Agency for Research on Cancer (IARC) under the World Health Organisation (WHO) on the association of coffee, tea and yerba mate with cancer. The publication discusses the factors involved in oesophageal cancer and the research conducted to date.

Yerba mate under fire for accusations. Is it actually carcinogenic?

As the researchers reported, scary articles began to appear in the press. A lot of fuss was made by an article published in 2009 in the Los Angeles Times – “Yerba mate: Sip, don't gulp”. On the basis of this text, further considerations began to emerge as to whether yerba mate was harmful. Each of these texts mentioned the two previously mentioned factors of mate's alleged carcinogenicity, but omitted very important facts. Firstly, the presence of polycyclic aromatic hydrocarbons (PAHs) in it is not so clear. Yes, they do occur in mate, as it is related to the way it is produced. The leaves and twigs of Ilex paraguariensis are subjected to thermal treatment, through drying with fire and smoke. By force, yerba mate produced in this way must contain smoke-derived components. The concentration of PAHs in traditionally processed holly has been found to be around 30 micrograms per kilogram. Is this a lot or a little? It is difficult to assess without context, and unfortunately this is precisely the “bare” data often given in articles pointing out the harmfulness of yerba mate. As it turns out, a similar amount, 30 μg/kg PAH, is found in cocoa, smoked meat contains about 50 μg/kg PAH, while grilled meat is up to 320 μg/kg PAH! The conclusion is simple – harmful substances are present in yerba mate just like in many other foods, but the amount does not threaten our health. Otherwise, the products would be withdrawn from circulation by the institutions that very carefully keep an eye on this. Secondly, the hot water with which the infusion is poured can increase the risk of illness, but we are talking about really high temperatures. A hot drink irritates the oesophagus and, in turn, any burns or micro-damage can increase the risk of disease. At this point, we would like to remind you that yerba mate is poured with cooled water, not boiling water, which is also often forgotten in articles denigrating the Guarani Indian brew.

Yerba mate not carcinogenic after all? Withdrawal of charges

In 2016, the International Agency for Research on Cancer (IARC) refuted the conclusions reached in a monograph it had published 25 years earlier. It re-examined the studies conducted and concluded that there is no evidence of carcinogenicity of yerba mate per se. The aforementioned PAHs are indeed present in mate, but their content is almost trace, comparable to the amount found in the food we eat every day. In addition, much more PAHs are found in coffee or grilled meat. Drinking hot yerba mate, on the other hand, can contribute to cancer just as much as drinking any other beverage at high temperatures (above 65 °C), even water alone. What's more, after reviewing a study conducted more than 25 years earlier, it was found that the wrong research group had been selected for the project. Many of the people who were studied were compulsive smokers and had a habit of smoking cigarettes while drinking yerba mate. As it turned out, blood vessels dilated under the influence of heat better absorb substances – not only good ones, but also harmful ones, including carcinogenic ones, such as tobacco smoke. Hence the misconception that drinking yerba mate contributes to cancer.

Is mate tea carcinogenic? Latest reports

The latest uproar over the alleged carcinogenicity of yerba mate was caused by an article in the British newspaper The Sun. The article, with a terrible title comparing drinking mate tea to smoking 100 cigarettes, referred to scientific publications, all of which repeat virtually the same thesis – yerba mate may indirectly contribute to cancer risk through its PAH content and drinking the brew at high temperatures. The article largely did not refer to the most recent studies at all. It listed publications from 2008 and 2019 that described the effects of drinking high-temperature drinks – in general, not just yerba mate. The title of the article itself is a reference to a 2012 publication, where the exact PAH content of a serving of the brew was calculated and compared to the total PAH content of five packets of cigarettes. It added, however, that one should be careful when comparing drinking yerba mate to smoking cigarettes, because the substances they provide are absorbed into the body in two different ways – through the stomach and through the lungs, which makes a significant difference. Recent studies are also mentioned, although no specific reports are given. Presumably this refers to a text published at the end of January 2022 by the British scientific journal Polycyclic Aromatic Compounds, which again focuses on the polycyclic aromatic hydrocarbon content of an infusion of Ilex paraguariensis leaves.

A rash of articles on the alleged harm of yerba mate

"Drinking a serving of yerba mate is as dangerous as smoking 100 cigarettes!" – these types of sentences in headlines shout out to us from time to time from health websites. Catchy, enticing to click and read and, above all, influencing the emotions of the audience. This is how unnecessary confusion and rumours are created. Can we completely refute the claim that yerba mate can contribute to cancer and is therefore carcinogenic? No. We are not scientists or health experts, so we cannot argue with professional studies. However, we think that the sentence quoted at the beginning of this paragraph is greatly exaggerated and puts in a completely bad light a beverage that is not at all more harmful than ordinary tea or coffee, but in fact contains far more health-promoting ingredients and has more valuable properties. What's more, studies (so far conducted in vitro and on mice and rats) prove that yerba mate, in addition to a number of other positive effects, can even prevent the formation of cancer cells!

An alternative for those who still have doubts

Despite our attempts to explain that yerba mate is not at all harmful, we cannot change the headlines of the articles that have already been published on the internet. We understand that some people may still be concerned. So if you have doubts that yerba mate dried by the traditional method, using fire and smoke, may contain harmful substances, there is a solution: yerba mate green! This is a Brazilian variety that is made by drying the leaves of Ilex paraguariensis using hot air. In addition, the drying stage is omitted during production, so that the dried leaves retain their luscious green colour. The best example of green mate is the Brazilian brand Verde Mate Green, which you can find in our shop in around 50 unique flavour variations. If you want to take 100% care of your health, without sacrificing the wonderful properties and taste of the holly infusion, we recommend you try Verde Mate!

Source of information:

1. Wikipedia: Mate, Polycyclic aromatic hydrocarbon.
2. A. Gawron-Gzella et al., Yerba Mate – A Long but Current History, Nutrients, 2021.
3. C.I. Heck, E.G. De Mejia, Yerba Mate Tea (Ilex paraguariensis): A Comprehensive Review on Chemistry, Health Implications, and Technological Considerations, Journal of Food Science, 2007.
4. Coffee, Tea, Mate, Methylxanthines and Methylglyoxal, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 51, 1991.
5. E. De Stefani et al., Mate drinking and risk of lung cancer in males: a case-control study from Uruguay, Cancer Epidemiology, Biomarkers & Prevention, 1996.
6. E. Conis, Yerba mate: Sip, don’t gulp, Los Angeles Times, 2009.
7. Drinking Coffee, Mate, and Very Hot Beverages, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans Volume 116, 2018.
8. T. Williams, Drinking this tea is as dangerous as ‘smoking 100 cigarettes’: study, The Sun, 2022.
9. M. V. Panzl et al., Evaluation of Polycyclic Aromatic Hydrocarbons in Dried Leaves of Yerba Mate (Ilex paraguariensis) and Their Extraction into Infusions, Polycyclic Aromatic Compounds, 2022.