Uruguay

Maté, marcela, living plant knowledge and a hard question: when does a traditional practice become evidence-based care?

Evidence at a glance

Cancer prevention: Uruguayan case-control studies found associations between very hot/high-volume maté and esophageal squamous-cell cancer. IARC classifies drinking very hot beverages (roughly above 65°C) as probably carcinogenic. This is an important prevention question, not evidence that mate is an anticancer treatment.
Cardiometabolic health: individual short-term mate studies have reported changes in blood pressure or LDL cholesterol. However, the controlled pooled comparison in a September 2026 systematic review found no significant lipid benefit. No trial reviewed here established prevention of heart attacks, strokes or diabetes.
Respiratory symptoms: a 2025 open-label randomized trial of marcela flower infusion suggested faster resolution of some mild respiratory symptoms, but nearly 43% of randomized participants did not complete symptom monitoring, limiting confidence.
Neurologic disease and cannabis: regulated cannabinoid medicines have evidence for selected symptoms, notably multiple-sclerosis spasticity, but formulations and indications differ. Uruguay’s legal access does not itself establish effectiveness.
Traditional knowledge: original ethnobotanical studies document plants used for digestive, respiratory, urinary and other conditions. Documentation of use is not evidence of clinical benefit.

Limits: This is a selective country evidence chapter, not a systematic review. Most cited treatment trials were conducted outside Uruguay; clinical findings apply to the specific tested preparation and population. Sources were checked November 5, 2026.

The people behind the plants

A mate gourd and thermos are familiar sights in Uruguay, but drinking mate is first a social and daily practice, not a prescribed treatment. Ilex paraguariensis is shared across the Southern Cone, and preparation—including water temperature, serving size, smoked or unsmoked leaves, and repeated refills—matters. Uruguay should not be reduced to a single herb or to a single ancestral tradition.

The 2019 original ethnographic study by Gregorio Tabakian (DOI 10.30972/bon.2823855) used interviews and participant observation in Tacuarembó and Canelones, documenting 138 medicinal plant species with uses reported especially for digestive, sensory and respiratory concerns. The authors contrasted influences of Indigenous and European traditions in those specific communities. These results are descriptions of what interviewees knew and practiced—not prevalence estimates for all Uruguayans, nor treatment efficacy trials.

A November 5, 2024 network and qualitative study (PMID 39501258) in the Quebradas del Norte area of Rivera examined how locally used medicinal plants form an interconnected knowledge system. Reported uses included urinary, digestive and circulatory complaints. The authors described continued use alongside formal health care and emphasized ecological and knowledge conservation. Preserving communities’ agency, the right not to disclose knowledge, and botanical identity matters as much as a chemical assay.

These studies should not be conflated with the researchers having clinically validated the remedies. The cultural origin of one recorded practice does not define every Indigenous, rural or urban household.

Cancer risk: what the Uruguay studies actually found

Maté temperature and esophageal cancer

An original 1990 Uruguay hospital case-control study (PMID 2295081) compared 261 people with esophageal squamous-cell carcinoma with 522 hospital controls. High daily mate consumption was associated with greater odds of esophageal cancer; smoking, alcohol and dietary exposures were also relevant. This design is vulnerable to recall bias, hospital-control selection and residual confounding.

A separate 2003 Montevideo hospital case-control report (PMID 12814995) included 344 cases and 469 controls recruited during 1988–2000. Compared with people reporting warm-to-hot mate, those reporting very hot mate had an adjusted odds ratio of 1.87 (95% CI 1.17–3.00) after adjustment for cumulative mate intake. Consumption over one liter per day was associated with an estimate of 2.84 (95% CI 1.41–5.73) versus nondrinkers. These are relative associations, not absolute cancer probabilities and not proof of a causal effect of mate ingredients. Older Uruguayan case-control series may share underlying populations and should not automatically be counted as independent trials.

The IARC/PAHO 2016 monograph announcement classified drinking very hot beverages (roughly above 65°C) as Group 2A, probably carcinogenic to humans, with esophageal cancer as the outcome of concern. Mate consumed at temperatures that are not very hot was Group 3—not classifiable as to carcinogenicity—not certified harmless and certainly not cancer-protective.

Practical distinction: allowing a hot drink to cool to a comfortable temperature addresses the specific thermal concern more directly than purchasing an ‘antioxidant’ mate product. Smoking and alcohol exposures require attention as separate established cancer risks. This chapter does not make a personal temperature prescription or claim that avoiding hot mate eliminates esophageal cancer risk.

Does mate or marcela treat cancer?

No original human trial verified for this chapter established that maté, marcela or a local medicinal-plant preparation reduces tumor size, cancer recurrence or mortality. Antioxidant findings, anti-inflammatory mediators and cancer-cell inhibition in culture are not human tumor outcomes. The observational maté literature addresses risk, not therapy. A herbal infusion should not replace cancer treatment or nutrition and symptom evaluation.

Cardiometabolic health: hopeful signals, important null results

A 2009 single-blind study (PMID 19694438; DOI 10.1021/jf901660g) included 102 adults across normal-lipid, dyslipidemic and statin-treated groups. Participants consumed a research mate infusion (330 mL three times daily for 40 days). LDL cholesterol declined from baseline in several groups; triglycerides did not change. This was a short lipid-biomarker study with important design limitations, not proof that mate prevents cardiovascular events. Its regimen is a study exposure, not a drinking recommendation.

The 2025 randomized controlled crossover study (DOI 10.1002/mnfr.70065; NCT06729905) examined 52 generally healthy or moderately at-risk nonhabitual consumers in Spain. Eight-week mate and comparator periods showed some blood-pressure and inflammatory-marker differences; in participants with hypercholesterolemia, both mate and the control drink improved some lipid values, complicating attribution. There were no cardiovascular-event endpoints. This is the same trial discussed in the Paraguay and Argentina chapters, not a separate Uruguay-specific study.

Most importantly, a systematic review published September 21, 2026 (DOI 10.52379/mcs.v10.732) included nine studies qualitatively and seven in quantitative synthesis. Compared with controls, the pooled LDL mean difference was 0.74 mg/dL (95% CI −6.10 to 7.58), with no statistically significant difference; total cholesterol, HDL and triglycerides were also not significantly different. Within-group before/after improvements appeared more favorable, but these do not establish causation and component studies are not additional independent evidence beyond the originals.

Clinical interpretation: a culturally valued drink may coexist with healthy habits, but it is not an evidence-based substitute for statins, hypertension therapy, diabetes medication, dietary counseling or activity. Caffeine may worsen sleep, anxiety, reflux or palpitations, particularly in susceptible people; beverage potency varies. Any claimed interaction with specific cardiovascular drugs needs compound-specific verification rather than assumption.

Marcela: traditional digestive and respiratory use

Achyrocline satureioides (marcela or macela) is a South American flowering plant used in infusions for digestive discomfort and other complaints. Naming the Latin species matters: the flower infusion, a concentrated ethanol extract and an isolated flavonoid are not interchangeable. Reported cultural use is important in its own right, but it does not demonstrate efficacy for inflammatory bowel disease, cancer, asthma or autoimmune illness.

A human trial, and why its limitations matter

A June 9, 2025 Brazilian randomized, open-label comparative study (PMID 40573256; DOI 10.3390/ph18060861; ReBEC RBR-8g6f2rv) studied a 14-day course of A. satureioides inflorescence infusion twice daily versus an Malus domestica (apple) infusion in adults with mild respiratory infections. 240 people were randomized, but only 138 completed symptom monitoring (72 marcela, 66 comparator), leaving approximately 42.5% without complete symptom follow-up. Reported resolution of sore throat and sneezing was faster in the overall analysis; cough and dyspnea were not significantly improved overall. Some COVID-status and vaccination subgroups appeared favorable, but subgroup multiplicity and missing follow-up weaken inference.

The study’s description uses ‘placebo-controlled’, yet participants and researchers were not blinded to the infusion assignment; symptom outcomes were self-reported. The trial was conducted in Brazil, not Uruguay. It did not establish prevention of pneumonia, improvement of chronic obstructive pulmonary disease, prevention of asthma attacks, benefit in immunocompromised oncology patients or reduced mortality. Repeat blinded trials with robust follow-up are needed.

What does ‘safe’ mean here?

A 2004 Uruguayan original animal toxicology study (PMID 15507360; DOI 10.1016/j.jep.2004.08.013) found little acute toxicity under the tested conditions for an aqueous marcela extract in rodents, including liver-enzyme and histological observations. That result does not establish human chronic liver or kidney safety, safety in pregnancy, safety during chemotherapy or the absence of herb–drug interactions. Exact product composition, plant identification, contaminants and route matter.

Evidence for putative antioxidant, neuroprotective, immunomodulatory or anti-inflammatory activities is largely laboratory or animal research. A signal in a mouse inflammation model should never be presented as demonstrated benefit for multiple sclerosis, rheumatoid arthritis, lupus or cancer.

Cannabis: legal access is not the same as an indication

Uruguay offers a distinctive contemporary policy context. Its Ministry of Public Health notice dated March 2, 2023 describes a regulated pathway for prescribed cannabis-based pharmacy preparations and specified quality controls under Decree 56/023. That is a statement about authorization and quality oversight, not a demonstration that cannabis cures a disease. Formulations and medical use must be checked against current local law and clinical circumstances.

Cancer symptoms

The 2024 ASCO guideline (DOI 10.1200/JCO.23.02596) advises against cannabis or cannabinoids as a cancer-directed treatment outside a clinical trial. For refractory chemotherapy-related nausea despite appropriate standard prophylaxis, selected quality-controlled oral cannabinoids may be considered as adjuncts with varying evidence strength. Evidence for cancer pain, appetite and other symptoms is insufficient for broad recommendations. See the existing nausea evidence brief, immunotherapy safety record, and long-form cannabis review.

Neurologic illness

A 2022 Cochrane review of cannabinoid medicines for multiple sclerosis found evidence that standardized nabiximols can reduce patient-reported spasticity over several weeks. Long-term adverse effects were less certain; cognition and psychiatric effects remain important. This cannot be assumed for unregulated smoked cannabis, homemade oils or every CBD preparation.

Potential harms include sedation, dizziness, impaired driving, psychological effects and drug interactions. ASCO cautions against high-dose oral CBD for cancer symptom management outside trials because benefit is unproven and elevated liver enzymes are a concern. Some interactions—for example with anticoagulants, immunosuppressants and sedatives—require individualized pharmacy review.

A practical safety map

Heat and cancer: very hot mate is the strongest country-specific harm signal in this chapter. The relevant endpoint is esophageal cancer incidence association, not cancer treatment.
Heart and metabolism: mate contains variable caffeine; screen for insomnia, tachyarrhythmia, anxiety, reflux and possible stimulant co-exposures. No demonstrated reduction in heart attack or stroke.
Liver and kidneys: a low-acute-toxicity rodent result for marcela cannot clear concentrated products for chronic use; screen active liver/kidney disease and all medicines.
Immune and inflammatory conditions: herb effects in cultured cells are not demonstrated control of autoimmunity. Avoid replacing immunosuppression or other disease-modifying therapy with infusions.
Oncology interactions: disclose all herbal extracts and cannabinoid products to the treating team, especially during anticancer treatment and when taking anticoagulants, sedatives, transplant drugs or other narrow-therapeutic-index medicines.
Respiratory safety: the marcela trial concerned mild acute infections, not chronic airway disease; worsening dyspnea, hypoxia, fever during chemotherapy, or persistent symptoms warrant medical assessment.

A drink, plant tea, concentrated supplement and prescription-grade cannabinoid product can have markedly different exposure and risk profiles. No plant is ‘safe because natural’; equally, neither cultural use nor a theoretical interaction justifies a blanket claim that every preparation is harmful.

What would stronger evidence look like?

For mate and metabolic risk: adequately powered randomized trials using clearly described preparations, controlled temperature, appropriate comparators, adherence monitoring and clinical rather than only surrogate endpoints. For marcela: prospectively registered, blinded multicenter studies with transparent prespecified symptom endpoints, high follow-up and explicit hepatic, renal and adverse-event monitoring. For cancer-related traditional remedies: studies must measure clinically meaningful patient outcomes and distinguish symptom relief from tumor control.

A helpful question for every traditional treatment is: What exactly was prepared, who used it, why did they use it, and which specific result was tested in people? Respect for the people who preserve knowledge does not require exaggerating the evidence.

Sources and what was actually checked

Tabakian, Bonplandia, 2019; DOI 10.30972/bon.2823855 — original Uruguayan ethnobotanical field research; full abstract, methods summary.
Castiñeira Latorre et al., 2024; PMID 39501258; DOI 10.1186/s13002-024-00739-z — Uruguay medicinal-knowledge network analysis; original abstract and accessible full-text search.
De Stefani et al., Cancer Research, 1990; PMID 2295081 — original hospital case-control esophageal-cancer study; abstract, selected manuscript context.
Sewram et al., CEBP, 2003; PMID 12814995 — original Uruguay esophageal-cancer case-control study; primary abstract and journal text.
IARC/PAHO, June 15, 2016 — hazard classification for very hot beverages.
de Morais et al., 2009; PMID 19694438; DOI 10.1021/jf901660g — original short-duration lipid study; publisher/abstract; full-text methods not independently appraised.
Bravo et al., 2025; DOI 10.1002/mnfr.70065; NCT06729905 — original controlled crossover mate trial; full accessible publisher article; same study referenced in other country chapters.
Rolon et al., September 21, 2026; DOI 10.52379/mcs.v10.732 — synthesis, not additional independent trials; primary article abstract reviewed.
Bastos et al., June 9, 2025; PMID 40573256; DOI 10.3390/ph18060861 — original Brazilian randomized open-label respiratory-symptom study; publication abstract and indexed full-text excerpts; ReBEC RBR-8g6f2rv.
Rivera et al., 2004; PMID 15507360; DOI 10.1016/j.jep.2004.08.013 — original animal marcela safety research; abstract only.
Uruguay Ministry of Public Health, March 2, 2023 — official regulatory notice.
ASCO, 2024; DOI 10.1200/JCO.23.02596 and Cochrane, 2022; DOI 10.1002/14651858.CD013444.pub2 — professional guidance/review; underlying trials not counted separately here.

Evidence last checked: November 5, 2026. Abstract-only sources and source-access limitations are identified above. This is an educational, selective appraisal, not a prospective clinical trial, systematic review, personal recommendation or comprehensive inventory of Uruguay’s many health traditions.

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