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Health Warning: Yerba Mate Tea Prevents and Causes Cancer

Tim Boyer's picture
Yerba Mate Tea

A recent news release touts the potential benefits of drinking Yerba mate tea toward colon cancer prevention. However, what the release does not mention is that Yerba mate tea is also listed as a carcinogen toward the development of other types of cancers as well. Read on to discover why drinking Yerba mate tea to prevent cancer may cause cancer instead.

A press release issued by the University of Illinois, Urbana announced the publication of one lab’s recent findings in the journal Molecular Nutrition & Food Research that components isolated from the Yerba mate tea demonstrated anti-cancer properties that led to the death of cultured colon cancer cells. Yerba mate tea is an herbal infusion of the plant Ilex paraguariensis and is drunk primarily in Argentina, Uruguay and southern Brazil. The tea is also popular in the U.S. due to claims that it is beneficial to health.

In the study, organic solvents were used to extract specific compounds from dried Yerba mate tea leaves followed by purification and biochemical identification. Various forms of the components are referred to caffeoylquinic acids (CQA) that are well-known for their anti-inflammatory and other properties.

The objective of the study was to isolate and purify diCQAs from Yerba mate tea leaves and assess their anti-inflammatory and anti-cancer capabilities under cell culture conditions and explore their mechanism of action. Inflammation is often a precursor to the development of cells turning cancerous.

What the researchers found was that not only did the diCQA compounds inhibit an induced inflammatory response in some cell lines, but that they also caused colon cancer cells to go into a state of apoptosis—cell death.

The significance of the study is that it provided more data toward understanding the mechanism of action and thereby the potential therapeutic benefits of compounds such as CQA derivatives toward the treatment of disease such as colon cancer. The researchers concluded that their results suggest that diCQAs in Yerba mate tea could be potential anti-cancer agents that could mitigate other diseases also associated with inflammation.

In fact, in a press release statement, Elvira de Mejia, a U of I associate professor of food chemistry and food toxicology states that, "We believe there's ample evidence to support drinking mate tea for its bioactive benefits, especially if you have reason to be concerned about colon cancer. Mate tea bags are available in health food stores and are increasingly available in large supermarkets."

The press release also reports that the researchers are working on a study that compares the development of colon cancer in rats that drank mate tea as their only source of water with a control group that drank only water—which should prove interesting as Yerba mate tea is listed as a carcinogen.

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According to an article titled “Carcinogenic Food Contaminants” in the journal Cancer Investigation, Yerba mate tea is classified by the International Agency for Research on Cancer (IARC) as “Probably Carcinogenic to Humans.” The classification is due to multiple studies that have demonstrated an association between hot mate tea and oral, oropharyngeal, head and neck, and esophageal cancer.

Initially, the risk from drinking Yerba mate tea was hypothesized to be dose and temperature dependent. In other words, the hotter and the more tea consumed—the higher the risk of developing cancer. It is theorized that a hotter tea will lead to increased leaching out of carcinogens in the tea leaves and/or the heat may cause inflammation of the oral tissues while drinking.

Later studies, however, revealed that temperature did not appear to make a difference. Rather, that the number of infusions using the same tea leaves repeatedly is what appears to increase the risk of developing cancer. Research has shown that Yerba mate tea leaves possess high levels of cancer-causing polycyclic aromatic hydrocarbons (PAHs).

In a study comparing the leaves of the eight commercial Yerba mate tea products, researchers found that Yerba mate leaves contain PAH concentrations ranging from 2 to 11 times the levels found in green tea leaves and the PAH levels were comparable to those achieved by smoking a pack of cigarettes a day.

However, the good news is that drinking the occasional cup of Yerba mate tea is unlikely to cause cancer. The concern, however, is that if the tea is prepared and consumed the traditional way with copious amounts of tea that has been infused multiple times using the same tea leaves, that the resulting high levels of PAHs may then put a person at risk of developing cancer.

Image Source: Courtesy of Wikipedia


1. ”Dicaffeoylquinic acids in Yerba mate inhibit NF-κB nucleus translocation in macrophages and induce apoptosis by activating caspases-8 and -3 in human colon cancer cells” Molecular Nutrition & Food Research Vol. 55, Issue 10; Sirima Puangpraphant, Mark A. Berhow, Karl Vermillion, Greg Potts and Elvira Gonzalez de Mejia.

2. “Carcinogenic Food Contaminants": Cancer Investigation 2007 Apr-May: 25(3); 189-196; Christian C. Abnet.

3. “High Levels of Carcinogenic Polycyclic Aromatic Hydrocarbons in Mate Drinks” Cancer Epidemiol. Biomarkers Prev., May 2008 17; 1262; Farin Kamangar, Michele Schantz, Christian Abnet, Renayo Fagundes and Sanford Dawsey.



If you carefully read statistics on cancer in Argentina it is seen clearly that the types of cancer that mentions the article are almost nonexistent. The immense majority in our country drink mate tea ... it´s 100% legal and like with any other food it´s controled by the national sanitory department. Mate has been consumed in Argentina since the birth of our country and is a highly nutritious and harmless drink. In fact many poor people make their living almost on yerba mate. A piece of bread and a cup of mate could be the only meal of the day. According to Dr. Mowrey, Director of Mountainwest Institute of Herbal Sciences, one group of investigators from the Pasteur Institute and the Paris Scientific Society concluded that Yerba Mate contains "practically all of the vitamins necessary to sustain life." They focused especially on Pantothenic Acid, remarking that it is "rare to find a plant with so much of this significant and vital nutrient. . . It is indeed difficult to find a plant in any area of the world equal to Mate in nutritional value."
I do agree mariano. Drinking a green leaf shudnt put ourselves higher risk of cancer. We must remember that ALL LEAF in this world provide nutrient that pulled from the soil underneath. But we should not consume it if after dried and processed as it's not a fresh medicine may put ourselves at risk after eating it.
One of the best anti-cancer teas is Taheebo Tea. Other names: Lapacho and most commonly known name Pau D'Arco. It's very affordable. "Organika" company in Canada makes it among many other wonderful supplements.
I wonder if the carcinogenicity of the tea has anything to do with the pesticides that may be applied, as I've heard that applies to the Cat's Claw herb. Personally I have not had good results from drinking yerba mate' -- it actually makes me depressed and constipated! For those reasons I have no longer consumed it, and it looks like I may have been right. Certainly we need more truly-objective scientific studies of herbs and drugs. Thank you for providing this vital information!
From what I have learned, the PAH's are caused primarily by the drying process, which is actually a "smoking" process of the leaves, before you EVER buy them. So the water temp doesn't alter the PAH's (probably) but if you get "Fuerte" it is most likely worse than "Suave", and the best would be Air Dried. HOWEVER, even in the Air Dried, certain brands had very low PAH's and others higher. I know that Guayaki did testing on their San Mateo and it is air dried and had lower PAH's than many green teas. I used to drink Rosamonte ALL the time, but now I ONLY drink Guayaki-And I would suggest you all do the same, the San Mateo blend, at the very least, UNTIL we know more...............Smoking of anything is likely to raise carcinogenic risk.