Is Yerba Mate Safe?
Drinking mate, an infusion of the herb ilex paraguariensis, is very common in several South American countries, and has been associated with an increased risk of esophageal cancer. This increased risk may be attributed to drinking mate very hot, or to mate’s potentially carcinogenic contaminants, such as polycyclic aromatic hydrocarbons (PAHs). Mate leaves are often dried with wood and smoke and therefore commercial samples may have high amounts of PAH.
A polycyclic aromatic hydrocarbon (PAH) is a hydrocarbon—a chemical compound containing only carbon and hydrogen. Many of them are found in coal and in oil deposits, and are also produced by the thermal decomposition of organic matter—for example, in engines and incinerators or when biomass burns in forest fires. PAH4 is the sum of four different polycyclic aromatic hydrocarbons, named benzo[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) measured at maximum levels.
The following table compares the results from a study of 8 different brands of yerba mate and test results from our unsmoked organic yerba mate.
| PAH4 | 8 Brand Range ng/g | 8 Brand Average ng/g | GYM Unsmoked Organic Yerba Mate ng/g |
| Benz(a)anthracene | 31.9 - 99.9 | 68.8 | .0000145 |
| Chrysene | 42.3 -154 | 115 | .0000157 |
| Benzo(b)flouranthene | 13.3 -76.3 | 62.8 | .0000128 |
| Benzo(a)pyrene | 10.3 - 72.9 | 32 | .0000149 |
| Sum PAH4 | 278.6 | .0000579 |
We do not know what brands were used in this study. The results of the analysis on our organic yerba mate are from an analytical report on a batch from 2019 submitted by our producer. All of their unsmoked organic is tested to make sure it meets EU standards before shipping.
It is important to note that there have been no studies directly connecting the PAHs in yerba mate to cancer. All of the research papers we have seen use the words possibly and it may be. More studies are needed to make a definitive connection.
Here are the two studies we used for this report.
Where do the PAHs come from?
1. When yerba mate comes from the field it is immediately put into a secado which is a large tumbler with a wood fire and a fan blowing the hot air and smoke over the leaves and stems.
Check out this video from Pipore, about 2.5 minutes in they show the secado in action. This has the effect of blanching the yerba to remove any dangerous bacteria and drying it down to a targeted moisture. If a company is using one of these it cannot be considered "unsmoked".
2. The second step is the drying process which can take 12-24 hours depending on the company. Some companies add smoke to the dryers to create their characteristic flavor.
This is one of the reasons for the broad ranges in test results.
Our unsmoked organic yerba mate products are never exposed to smoke or high heat anywhere in the process. The technology is relatively new and growing.