An interventional study of Yerba Mate and Placebo in Overweight (BMI > 25) and Obesity & Overweight, sponsored by University of North Alabama. Completed at 1 site in United States. Open to participants aged 60 Years and older. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by University of North Alabama · Not applicable, Interventional, and Basic science
The purpose of this study was to find out whether taking yerba mate, a plant-based supplement, could improve health in adults aged 60 years or older with excess body fat. Researchers examined how the body uses fat during walking, blood cholesterol levels, body composition, strength, mobility, thinking skills, and well-being. They also explored changes in inflammation, gene activity, and gut bacteria.
Participants took yerba mate capsules for six weeks and placebo capsules for six weeks, with a four-week break between the two periods. The placebo contained no yerba mate. The order was assigned by chance. Participants and the researchers conducting the tests did not know which capsules participants were taking during each period.
Participants completed blood tests, body measurements, walking tests, strength and mobility tests, thinking tasks, and questionnaires. Researchers compared the results from the yerba mate and placebo periods.
This randomized, double-blind, placebo-controlled crossover study evaluated the physiological and molecular effects of yerba mate supplementation in older adults with excess adiposity. The study included two 6-week supplementation periods separated by a 4-week washout. Participants received yerba mate extract during one period and placebo during the other, in a randomized order. The crossover design allowed participants to serve as their own controls.
Clinical, functional, and cognitive assessments were conducted before and after each supplementation period. Laboratory testing included fasting blood collection, body composition assessment using dual-energy X-ray absorptiometry, and indirect calorimetry during walking at standardized treadmill speeds to evaluate whole-body fat oxidation and walking economy. Physical function, muscle strength, cognitive performance, and self-reported health and well-being were also assessed.
Additional analyses examined circulating inflammatory markers, gene expression, and gut microbiota composition using samples collected at the end of each supplementation period. These analyses explored biological pathways potentially associated with the physiological responses to supplementation. Molecular analyses were performed in participant subsets according to sample availability.
Clinical outcomes were compared between supplementation conditions using measurements collected before and after each period. Inflammatory markers, gene expression, and gut microbiota outcomes were compared between conditions using end-of-period measurements.
3,767 studies on the registry are indexed under Overweight; 863 are open to participants now.
This study's enrollment of 25 is below the median of 73 across 3,263 interventional studies indexed under Overweight.
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Age 60 years or older.
Excess adiposity, defined by meeting at least two of the following criteria: body mass index ≥25 kg/m²; waist-to-hip ratio ≥0.90 for males or ≥0.85 for females; body fat percentage ≥25% for males or ≥35% for females.
Ability to walk independently on a treadmill for at least 10 minutes.
Ability to complete computerized cognitive assessments independently.
Stable medication use for at least 3 months.
Habitual caffeine intake below 300 mg/day.
Ability to provide written informed consent and comply with study procedures.
Exclusion Criteria:
Major uncontrolled chronic disease.
Diagnosed neurodegenerative disease or cognitive impairment, or Montreal Cognitive Assessment score below 18.
Diagnosed psychiatric disorder or recent initiation of psychotropic medication.
Mobility limitations preventing completion of treadmill testing.
Uncontrolled hypertension, insulin-treated diabetes, or clinically significant hepatic or renal disease.
Untreated sleep apnea or cardiac arrhythmias requiring antiarrhythmic therapy.
Allergy to yerba mate or use of stimulant supplements.
Active smoking.
Antibiotic or probiotic use within the previous 3 months.
Vegan or vegetarian diet.
Physical activity exceeding 10 hours per week.
Participants received yerba mate extract (six 500-mg capsules daily; 3,000 mg/day) for 6 weeks
Dietary Supplement: Yerba Mate
Participants received placebo for 6 weeks, followed by a 4-week washout period
Dietary Supplement: Placebo
Yerba mate (Ilex paraguariensis) extract administered orally as six 500-mg capsules daily (3,000 mg/day) for 6 weeks. The extract had a 6:1 extraction ratio and was standardized to 37-40% chlorogenic acids and no more than 2% caffeine.
Placebo administered orally as six capsules daily for 6 weeks, following the same dosing schedule as the yerba mate intervention.
Also known as: Food starch
Fat Oxidation During Walking
Whole-body fat oxidation rate (g/min), calculated from oxygen uptake and carbon dioxide production measured by indirect calorimetry during standardized treadmill walking.
Time frame: Before and after each 6-week supplementation period.
Walking Economy
Oxygen cost of walking, expressed in milliliters of oxygen per kilogram of body mass per meter walked. The value is calculated by dividing mass-specific oxygen uptake in mL/kg/min by walking speed in meters per minute. Lower values indicate better walking economy.
Time frame: Before and after each 6-week supplementation period.
Fasting Triglycerides
Fasting triglyceride concentration (mg/dL), assessed using the Cholestech LDX system.
Time frame: Before and after each 6-week supplementation period.
Psychomotor Vigilance Task Reaction Time
Reaction time, expressed in milliseconds, during the computerized Psychomotor Vigilance Task, which assesses sustained attention and vigilance. Shorter reaction times indicate faster responses.
Time frame: Before and after each 6-week supplementation period.
Transcript Expression Fold Change
Expression of protein-coding and noncoding transcripts assessed using the Affymetrix Clariom D human microarray. Differences between yerba mate and placebo supplementation conditions are expressed as fold changes in transcript expression, with results reported individually for each transcript.
Time frame: At the end of each 6-week supplementation period.
Eriksen Flanker Task Incongruent-Trial Reaction Time
Reaction time, expressed in milliseconds, during incongruent trials of the computerized Eriksen Flanker Task, which assesses inhibitory control. Shorter reaction times indicate faster performance.
Time frame: Before and after each 6-week supplementation period.
Task-Switching Reaction Time
Reaction time, expressed in milliseconds, during the computerized task-switching task, which assesses cognitive flexibility. Shorter reaction times indicate faster performance.
Time frame: Before and after each 6-week supplementation period.
Fasting Blood Glucose
Fasting blood glucose concentration (mg/dL), measured using the Cholestech LDX system.
Time frame: Before and after each 6-week supplementation period.
Blood Pressure
Resting diastolic blood pressure (mmHg), measured using an automated upper-arm monitor after 5 minutes of seated rest.
Time frame: Before and after each 6-week supplementation period.
Interleukin-6 Relative Abundance Fold Change
Relative plasma interleukin-6 abundance assessed using a cytokine antibody array. Results are expressed as the dimensionless ratio of normalized signal intensity after yerba mate to that after placebo. A ratio of 1 indicates equal abundance between conditions; values above 1 indicate higher abundance after yerba mate, and values below 1 indicate lower abundance compared with placebo.
Time frame: After each 6-week supplementation period.
Relative Abundance of Gut Bacterial Taxa
Relative abundance of bacterial taxa in stool samples assessed by sequencing the V3-V4 region of the bacterial 16S ribosomal RNA gene. Results are expressed as percentages of bacterial sequencing reads assigned to each taxon, ranging from 0% to 100%. Higher percentages indicate greater relative representation of the taxon in the sample. Taxa are reported individually and compared between yerba mate and placebo supplementation conditions.
Time frame: At the end of a 6-week supplementation period.
Tumor Necrosis Factor Alpha Relative Abundance Fold Change
Relative plasma tumor necrosis factor alpha abundance assessed using a cytokine antibody array. Results are expressed as the dimensionless ratio of normalized signal intensity after yerba mate to that after placebo. A ratio of 1 indicates equal abundance between conditions; values above 1 indicate higher abundance after yerba mate, and values below 1 indicate lower abundance compared with placebo.
Time frame: After each 6-week supplementation period.
Interleukin-1 Beta Relative Abundance Fold Change
Relative plasma interleukin-1 beta abundance assessed using a cytokine antibody array. Results are expressed as the dimensionless ratio of normalized signal intensity after yerba mate to that after placebo. A ratio of 1 indicates equal abundance between conditions; values above 1 indicate higher abundance after yerba mate, and values below 1 indicate lower abundance compared with placebo.
Time frame: After each 6-week supplementation period.
Interleukin-10 Relative Abundance Fold Change
Relative plasma interleukin-10 abundance assessed using a cytokine antibody array. Results are expressed as the dimensionless ratio of normalized signal intensity after yerba mate to that after placebo. A ratio of 1 indicates equal abundance between conditions; values above 1 indicate higher abundance after yerba mate, and values below 1 indicate lower abundance compared with placebo.
Time frame: After each 6-week supplementation period.
Interferon Gamma Relative Abundance Fold Change
Relative plasma interferon gamma abundance assessed using a cytokine antibody array. Results are expressed as the dimensionless ratio of normalized signal intensity after yerba mate to that after placebo. A ratio of 1 indicates equal abundance between conditions; values above 1 indicate higher abundance after yerba mate, and values below 1 indicate lower abundance compared with placebo.
Time frame: After each 6-week supplementation period.
Monocyte Chemoattractant Protein-1 Relative Abundance Fold Change
Relative plasma monocyte chemoattractant protein-1, also known as C-C motif chemokine ligand 2, abundance assessed using a cytokine antibody array. Results are expressed as the dimensionless ratio of normalized signal intensity after yerba mate to that after placebo. A ratio of 1 indicates equal abundance between conditions; values above 1 indicate higher abundance after yerba mate, and values below 1 indicate lower abundance compared with placebo.
Time frame: After each 6-week supplementation period.
Cognitive Failures Questionnaire Total Score
Perceived cognitive failures assessed using the 25-item Cognitive Failures Questionnaire. Each item is scored from 0 to 4, yielding a total score from 0 to 100. Higher scores indicate more frequent cognitive failures and a worse outcome.
Time frame: After each 6-week supplementation period.
World Health Organization-Five Well-Being Index Score
Psychological well-being assessed using the World Health Organization-Five Well-Being Index. Five items are scored from 0 to 5. The summed score is multiplied by four to obtain a final score from 0 to 100. Higher scores indicate better psychological well-being.
Time frame: After each 6-week supplementation period.
15-Item Geriatric Depression Scale Total Score
Depressive symptoms assessed using the 15-item Geriatric Depression Scale. The total score ranges from 0 to 15. Higher scores indicate more depressive symptoms and a worse outcome.
Time frame: After each 6-week supplementation period.
Generalized Anxiety Disorder 7-Item Scale Total Score
Anxiety symptoms assessed using the Generalized Anxiety Disorder 7-Item Scale. Each item is scored from 0 to 3, yielding a total score from 0 to 21. Higher scores indicate greater anxiety symptom severity and a worse outcome.
Time frame: After each 6-week supplementation period.
Pittsburgh Sleep Quality Index Global Score
Sleep quality assessed using the Pittsburgh Sleep Quality Index. Seven component scores, each ranging from 0 to 3, are summed to obtain a global score from 0 to 21. Higher scores indicate poorer sleep quality and a worse outcome.
Time frame: After each 6-week supplementation period.
Fatigue Severity Scale Total Score
Fatigue severity and its impact on daily activities assessed using the nine-item Fatigue Severity Scale. Each item is scored from 1 to 7, yielding a total score from 9 to 63. Higher scores indicate greater fatigue and a worse outcome.
Time frame: After each 6-week supplementation period.
Brief Resilience Scale Mean Score
Resilience assessed using the six-item Brief Resilience Scale. Items 2, 4, and 6 are reverse-scored, and the six item scores are averaged. The mean score ranges from 1 to 5. Higher scores indicate greater resilience and a better outcome.
Time frame: After each 6-week supplementation period.
Plan to share: No — There is currently no plan to share individual participant data. Study findings will be disseminated through scientific publications and presentations using aggregate results.
No publications or documents are linked to this record.
Ran from Nov 2025 to primary completion in Jun 2026, 7 months.
Of 1,356 non-industry interventional studies with no phase under Overweight, half reached primary completion within 18 months of starting (the median), counting those still running; a quarter within 8 and three quarters within 38. This study's 7 months is below that.
Counting every sponsor, half of 1,472 studies reached it within 17 months; a quarter within 7 and three quarters within 36.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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University of North Alabama