Understanding What Are the PAH Levels in Yerba Mate?

October 19, 2025 •

5 min read

Multiple studies have detected polycyclic aromatic hydrocarbons (PAHs) in traditionally processed yerba mate, a result of the common smoke-drying method. While the presence of these compounds raises understandable concerns, particularly regarding long-term consumption, the amount that transfers into the final infusion is often minimal.

Quick Summary

Yerba mate's PAH content varies based on processing, with smoke-dried varieties having higher levels in the dried leaves. However, these compounds transfer poorly into the brewed infusion. The primary health risk is the high temperature of consumption, not the PAH content itself. Choosing unsmoked mate is a low-PAH option.

Key Points

PAH Presence: Traditionally smoke-dried yerba mate leaves contain polycyclic aromatic hydrocarbons (PAHs) formed during the drying process.
Low Transfer to Infusion: Despite high levels in the leaves, PAHs have low water solubility and only transfer in small amounts to the brewed mate infusion.
High Temperature is the Risk Factor: The main health risk is the high temperature of the brew (over 65°C), which can cause thermal injury to the esophagus, not the PAHs themselves.
Unsmoked Alternatives: Air-dried, unsmoked yerba mate varieties, often from Brazil, have significantly lower PAH content compared to smoke-dried brands.
Risk Reassessment: The IARC re-evaluated mate's carcinogenicity in 2016, attributing prior cancer associations to very hot liquid consumption and other lifestyle factors.
Minimize Exposure: To reduce PAH exposure, choose unsmoked mate, use water below boiling point (70-80°C), and avoid prolonged steeping.

The Origin of PAHs in Yerba Mate

Polycyclic Aromatic Hydrocarbons (PAHs) are a group of chemical compounds formed during the incomplete combustion of organic substances, such as wood, oil, or gas. In the context of yerba mate, the primary source of these compounds is the traditional processing method, which involves two thermal stages after harvesting: the quick scorching (sapeco) and the subsequent drying. Both stages, when performed using wood fires, can expose the leaves and stems to smoke and combustion products, allowing PAHs to accumulate on the surface.

This process is particularly common for mate produced in regions like Argentina and Paraguay, and is responsible for the characteristic smoky flavor preferred by many consumers. In contrast, some manufacturers, particularly in Brazil, have adopted modern air-drying techniques that avoid smoke exposure, resulting in a cleaner flavor profile and significantly lower PAH levels.

PAH Levels in Dried Leaves vs. Brewed Infusion

It is crucial to differentiate between the PAH concentration in the dried leaves and the amount that actually transfers into the brewed infusion that is consumed. Numerous studies have found that while dried yerba mate leaves can contain substantial PAH concentrations, only a small percentage of these compounds are extracted during brewing. This is because many of the carcinogenic PAHs, especially the heavier ones, are highly hydrophobic and have low water solubility.

Key factors influencing PAH transfer include:

Water Temperature: Higher temperatures increase the rate of extraction, though some studies suggest even hot infusions transfer a relatively low percentage of PAHs.
Steeping Time: Prolonged steeping may allow for greater transfer, though traditional consumption methods involving repeated, quick extractions also play a role.
Amount of Powder: The fine powder fraction of yerba mate tends to hold higher concentrations of heavier PAHs, and its presence in the infusion can increase overall intake.

A 2022 study showed a transfer rate of 0.11% to 0.54% for a group of PAHs in infusions that simulated traditional consumption, with a transfer of only 0.42% for benzo[a]pyrene. Another study found transfer rates of less than 12% for total PAHs and only about 2.1% for the more toxic PAH4 compounds.

Comparison of Processing Methods and PAH Exposure

Here is a comparison of traditional smoke-dried mate and modern air-dried mate, focusing on aspects relevant to PAH exposure.


Aspect	Traditional Mate (Smoke-Dried)	Air-Dried Mate (Unsmoked)
Drying Method	Dried over wood fires, exposing leaves to smoke and combustion byproducts.	Dried using hot air, without smoke exposure.
Primary PAH Source	Exposure to pyrogenic combustion products from wood smoke during processing.	Primarily environmental sources, with low levels of contamination.
Total PAH in Leaves	Higher concentration, varying significantly by brand and batch (e.g., studies show ranges from 536 to 2906 ng/g).	Significantly lower concentration compared to smoke-dried varieties.
PAH Transfer to Infusion	Low transfer rate, typically less than 12% for total PAHs, due to low water solubility.	Even lower, almost negligible transfer of PAHs to the infusion due to the low starting concentration.
Flavor Profile	Distinct, smoky flavor profile; aged for a period to develop flavor.	Fresh, grassy, or vegetal flavor profile; no smoky notes.
Health Concern (PAHs)	Potential for exposure via fine particles and ingestion, though moderate consumption risk is considered low.	Minimal concern regarding PAH exposure due to processing.

Reconsidering the Cancer Risk: Temperature vs. PAHs

Early epidemiological studies in South America linked yerba mate consumption with an increased risk of certain cancers, particularly esophageal cancer. However, more recent evaluations have clarified the underlying factors, shifting the focus away from PAHs as the main culprit. In 2016, the International Agency for Research on Cancer (IARC) reclassified its assessment of yerba mate, concluding there is no conclusive evidence that the mate itself is carcinogenic.

The most significant risk factor identified is the temperature at which the beverage is consumed. Drinking any beverage at very hot temperatures (above 65°C) can cause thermal damage to the esophagus, which is a known risk factor for esophageal cancer. Since yerba mate is traditionally consumed very hot in parts of South America, this behavior, combined with other lifestyle factors like smoking and alcohol consumption common in the study populations, was likely the primary driver of the observed cancer risks.

While some older studies noted PAH biomarker levels in heavy mate drinkers were comparable to those of smokers, the absorption pathways are entirely different (ingestion vs. inhalation), making a direct risk comparison inaccurate. A balanced view acknowledges the presence of PAHs in smoke-dried mate while recognizing that the risk is low, and that high-temperature consumption is the more pressing concern. For those seeking to further minimize risk, choosing an air-dried, unsmoked variety is a sensible option.

How to Minimize PAH Exposure and Risk

For consumers concerned about PAH levels in yerba mate, there are simple steps to reduce potential exposure without giving up the beverage entirely.

Choose Unsmoked Yerba Mate: Many reputable brands now offer unsmoked varieties, often labeled as 'green' or 'air-dried'. This is the most effective way to eliminate PAHs introduced during processing.
Brew with Moderate Temperature Water: Never use boiling water to brew your mate. A temperature of 70-80°C is standard and allows the infusion to cool slightly before drinking, significantly reducing the risk of thermal injury to the esophagus.
Moderate Your Consumption: As with many things, moderation is key. Heavy consumption of any caffeinated beverage can have side effects. Sticking to 1-2 liters per day is typically considered safe for most adults, though consulting a healthcare provider is always wise.
Use Quality Products: Opt for yerba mate from trusted manufacturers known for quality control. Some studies show brands from Brazil and those aged for longer periods may have lower PAH content.

Conclusion: A Balanced Perspective

The issue of what are the PAH levels in yerba mate has been a source of concern for many years, but modern research offers a more nuanced understanding. While traditionally smoke-dried yerba mate leaves do contain PAHs, the concentration that ends up in the final infusion is very low. A greater and more direct health risk comes from consuming the beverage at very high, scalding temperatures, which can damage the esophagus over time. By choosing unsmoked varieties and practicing safe brewing techniques, consumers can enjoy the many benefits of yerba mate with minimal concern regarding its PAH content. The conversation around yerba mate should focus on safe consumption practices rather than exaggerated fears about inherent carcinogenicity. NIH Study on PAHs and Mate

Frequently Asked Questions

PAHs, or polycyclic aromatic hydrocarbons, are chemical compounds that result from the incomplete combustion of organic materials. They are found in yerba mate because the traditional drying process involves exposure to wood smoke and flame.

For moderate consumption, the PAH levels are not considered a significant health threat. While the dried leaves contain PAHs, very little is transferred to the water infusion. Risk assessments indicate low concern for human health from moderate intake.

Modern scientific consensus points to the temperature of the liquid, not the mate itself, as the primary risk factor for esophageal cancer among heavy drinkers. The International Agency for Research on Cancer (IARC) has clarified this, attributing older studies' findings to a combination of very hot consumption and other risk factors like smoking.

To reduce PAH exposure, choose unsmoked, air-dried varieties of yerba mate. Also, avoid brewing with boiling water and allow the infusion to cool to a warm, but not scalding, temperature before drinking.

No. Processing varies by region. Traditionally, mate is smoke-dried. However, some brands, particularly Brazilian ones, now use air-drying methods to produce an unsmoked, lower-PAH product.

PAHs are also found in other smoked or grilled foods. While concentrations vary, a risk assessment has suggested the PAH exposure from moderate yerba mate consumption poses a low level of concern compared to other potential sources in the diet.

Yes, lighter PAHs are generally more water-soluble than heavier, more carcinogenic PAHs, meaning a higher percentage of these compounds may transfer from the leaves into the infusion.

Drinking any beverage, including water, at a very high temperature (above 65°C) can cause thermal burns to the cells of the esophagus. Over time, this chronic irritation is considered a more significant risk factor for esophageal cancer than the PAH content in the brew itself.