Are There Heavy Metals in Yerba Mate? A Look at Contamination and Safety

October 9, 2025 •

4 min read

A 2019 study in Brazil found that nearly half of processed yerba mate samples had levels of cadmium or lead exceeding regulatory limits for the dry leaf product. This discovery raises a crucial question for consumers: are there heavy metals in yerba mate, and what is the actual risk associated with drinking it regularly?

Quick Summary

Research shows that heavy metals like cadmium, lead, and mercury can be present in yerba mate leaves, primarily from natural soil absorption. However, studies consistently report that a very low percentage of these metals transfers into the brewed infusion, suggesting minimal consumer risk from normal consumption.

Key Points

Heavy Metals Are Present in Leaves: Yerba mate leaves naturally accumulate trace amounts of heavy metals like cadmium, lead, and mercury from the soil, a known characteristic of the plant.
Low Transfer to Infusion: The majority of heavy metals in the dry leaves do not leach into the brewed tea, with studies showing low transfer rates, mitigating health risks for most consumers.
Minimal Health Risk from Infusion: For the average consumer, the estimated dietary intake of heavy metals from yerba mate infusions falls significantly below safety thresholds recommended by organizations like the FAO/WHO.
Processing and Origin Matter: The concentration of heavy metals can vary depending on the plant's geographical origin, soil composition, and processing methods, including exposure to smoke during drying.
Choose Reputable Brands: Consumers concerned about heavy metal content can opt for certified organic products and research brands with rigorous third-party testing for contaminants to ensure quality and safety.

Sources of Heavy Metals in Yerba Mate

The presence of heavy metals in yerba mate is not always a sign of contamination, but can be a natural result of the plant's growth environment. The Ilex paraguariensis tree, from which yerba mate is derived, is known to have a strong capacity to absorb minerals from the soil. The primary sources of these metals in the final product are:

Soil and Geology: Yerba mate is often grown in specific geological regions in South America where the soil naturally has higher concentrations of certain minerals, including heavy metals like cadmium and nickel. The parent material of the soil, such as volcanic rock, can determine the baseline levels of heavy metals.
Environmental Pollution: Like all crops, yerba mate can be subject to environmental contamination from sources such as industrial waste, road traffic, and contaminated water used for irrigation. Atmospheric particle deposition can also contribute to lead levels on the leaves, especially if not washed during processing.
Agricultural Inputs: The use of phosphate fertilizers has been identified as a potential source of cadmium contamination in agricultural soils and crops. While this is a concern, some studies suggest its influence is complex and not always directly reflected in increased plant tissue levels.

The Impact of Processing and Preparation

The way yerba mate is processed and prepared significantly influences the final heavy metal content in your cup. It's a journey from the raw leaf to the brewed infusion, and at each step, concentrations can change.

Drying Process: A major contributor of contaminants is the traditional smoke-drying process, or barbacuá, which can introduce carcinogenic polycyclic aromatic hydrocarbons (PAHs) into the leaves. Some modern and organic producers use smoke-free drying to mitigate this risk.
Infusion vs. Dry Leaf: The most reassuring finding from scientific research is the low transfer rate of heavy metals from the dry leaf to the water during infusion. Studies show that only a small fraction of the total metal content in the leaf actually leaches into the brewed tea. For instance, one study found lead transferred at approximately 5%, and cadmium at around 10%.
Temperature and Time: The brewing conditions, such as water temperature and infusion time, can influence the extraction rate of minerals and metals. Hot water infusions typically extract slightly higher levels of some elements compared to cold infusions, but overall transfer remains low. The repeated use of the same leaves also affects concentrations in subsequent brews.

Comparison of Heavy Metal Content

This table illustrates the difference between heavy metal concentrations found in the dry yerba mate leaves and the subsequent infusions, based on scientific studies.


Contaminant	Concentration in Dry Leaf	Concentration in Infusion	Leaching Rate
Lead (Pb)	Up to 1.20 mg/kg	Very low to undetectable	~5-35% (varies widely)
Cadmium (Cd)	Up to 1.25 mg/kg	Low	~10-60% (varies widely)
Mercury (Hg)	Ultra-trace levels detected	Very low or undetectable	Low
Nickel (Ni)	Up to 4.86 µg/g	Variable, monitored for risk	Moderate, up to 15%

Health Implications and Regulations

While the presence of heavy metals can be unsettling, the health risk from consuming yerba mate infusions appears to be low for most people. The Provisional Tolerable Weekly Intake (PTWI) set by the FAO/WHO for metals like cadmium and lead is not exceeded by regular consumption for the majority of consumers, even in extreme scenarios. Regulatory bodies, such as Brazil's ANVISA, have set maximum permissible limits for contaminants in the raw product, but compliance is not always guaranteed, as highlighted in some retrospective studies.

For most individuals, the health benefits of yerba mate, including its potent antioxidant properties and essential minerals, outweigh the minimal risk associated with the low levels of metals that leach into the infusion. However, those with pre-existing conditions, especially kidney-related issues, should exercise caution and discuss concerns with a healthcare professional. Long-term, high-volume consumption, particularly in a manner that might increase intake (e.g., constantly refilling the same leaves without discarding the saturated grounds), is an area that warrants further research.

Choosing Safer Yerba Mate

Concerns over heavy metals and other contaminants like pesticides have led many consumers to seek out higher-quality, safer products. Key factors to consider when choosing your yerba mate include:

Source: Consider the geographical origin, as studies indicate variations in heavy metal content based on local soil geology.
Organic Certification: Opting for certified organic yerba mate ensures it is grown without synthetic pesticides or fertilizers, although it does not eliminate the possibility of naturally occurring soil metals. Look for certifications from trusted regulatory bodies.
Processing Method: Look for brands that use smoke-free drying methods to avoid PAHs, a separate but related concern.
Brand Reputation and Testing: Choose reputable brands known for transparent quality control and third-party testing for heavy metals and other contaminants. Some companies will provide certificates of analysis upon request.

Conclusion

Yes, studies have confirmed that heavy metals are present in yerba mate leaves, largely due to natural accumulation from the soil. However, the risk to human health from consuming the brewed tea is considered low, as only a small fraction of these metals transfers into the water. For most consumers, the health benefits of yerba mate infusions outweigh the risk associated with this low exposure. By choosing high-quality, preferably organic products with transparent sourcing and processing methods, consumers can further minimize their exposure to both heavy metals and other contaminants like PAHs, ensuring a safer and healthier beverage experience.

For more information on provisional tolerable weekly intake guidelines, consult the FAO/WHO Joint Expert Committee on Food Additives report: JECFA Safety Evaluations of Food Additives and Contaminants

Frequently Asked Questions

Scientific studies show that most yerba mate contains detectable trace amounts of heavy metals like lead and cadmium, primarily absorbed from the soil during growth. This is not unique to yerba mate, as many plants can naturally accumulate elements from their environment.

For most people, yes. While heavy metals are present in the leaves, the amount that transfers to the water during infusion is typically very low. Safety assessments based on average consumption indicate the intake is well within internationally recognized tolerable limits.

Industrial processing itself does not typically add heavy metals, but the leaves are not washed before drying. Contaminants can accumulate on the leaves from dust and environmental particles, particularly lead. The traditional smoke-drying process can also introduce other carcinogens, such as PAHs.

No. Organic certification guarantees the absence of synthetic pesticides and fertilizers, but it cannot prevent a plant from absorbing naturally occurring heavy metals from the soil. However, choosing organic can help avoid additional contaminants from agricultural chemicals.

Yes, to a small degree. Studies have found that hot water infusions can extract slightly higher levels of some elements compared to cold water, but the overall transfer remains minimal and is not considered a health risk for most consumers.

For very heavy, long-term consumers, particularly those with existing health concerns, it is wise to be more cautious. While studies suggest low risk for average consumption, the long-term effects of high-volume intake of contaminants warrant more research. Discussing your consumption habits with a healthcare provider is recommended.

You can minimize exposure by choosing certified organic brands that use smoke-free drying methods. Additionally, selecting brands with transparent quality control and third-party testing can provide assurance of contaminant levels. Opting for less frequent, high-volume consumption is also a prudent choice.