Benefits
Body fat in one 12 week extract trial; no pooled change in BMI or waist
In a small trial of 30 Korean adults with a BMI of 25 to 35, 3 g a day of a yerba mate water extract in capsules for 12 weeks lowered body fat mass, percent body fat and waist to hip ratio compared with placebo, while blood lipids did not change. Only 25 people finished. Pooled randomized trials, including other 3 g extract trials, found no change in BMI or waist size.
Body weight and waist size in pooled randomized trials
A meta-analysis of randomized trials found no significant effect of yerba mate on BMI (7 trials, rated high certainty) or waist circumference (8 trials), a null result that included two 6 week trials of 3 g a day of mate extract. In an 8 week crossover trial of three cups a day in normal weight adults new to mate, body weight did not change.
Fat oxidation and appetite ratings during exercise
In 12 active women, 2 g of yerba mate leaf capsules taken before a rest and 30 minutes of cycling raised fat oxidation compared with placebo (0.21 versus 0.17 g per minute) and lowered ratings of hunger and desire to eat. In 11 trained male cyclists, 5 g a day for 5 days raised fat use by 23% at low to moderate effort. Both were short crossover studies that did not measure body weight, so any effect on weight loss is uncertain.
Caffeine source with short-term focus and cycling results
One analyzed mate product had about 7.3 mg of caffeine per gram of leaf, so three 3 g cups supplied about 66 mg a day. In active women, 2 g of mate capsules raised self-rated focus, energy and concentration compared with placebo, and in trained cyclists 5 g a day for 5 days shortened a 30 minute time trial by about 2%.
Antioxidant enzyme PON-1 rose with brewed mate in an 8 week trial
In 142 adults aged 35 to 60 with overweight and untreated high blood lipids, 1 L a day of brewed mate for 8 weeks raised the antioxidant enzyme PON-1 by 9.7%, a larger change than with green tea or an apple tea control. Participants could not be blinded, and a mate company supplied the mate kits.
Blood antioxidant capacity in longer mate tea trials
In a 90 day randomized trial in 74 adults with high blood lipids, 1 L a day of mate tea raised serum antioxidant capacity and reduced glutathione, but the diet-only group without mate rose too, and PON-1 and oxidation markers did not change. In an 8 week crossover trial, antioxidant capacity rose by one lab method (FRAP) but not by another (ABTS).
Blood cholesterol results across mate studies
In a 40 day study without a placebo group, three 330 mL cups a day lowered LDL cholesterol about 8.6% from baseline in adults with high lipids. In an 8 week crossover trial, LDL fell in people with normal cholesterol, but the control drink lowered lipids as much in those with high cholesterol, and a meta-analysis of randomized trials found no significant LDL change.
Blood pressure and inflammatory markers in an 8 week crossover trial
In 52 adults new to mate, three cups a day for 8 weeks lowered blood pressure and several inflammatory cytokines. In the participants with high cholesterol, systolic pressure fell 8.2 mmHg, but the caffeine-free control drink also lowered pressure by about 3.4 mmHg. The trial was open label, and heart rate did not change.
Mechanism of action
Caffeine and theobromine in the leaf
Lab analysis of a roasted mate product found 7.34 mg of caffeine and 0.95 mg of theobromine per gram of dried leaf. Brewed as three 3 g cups a day, that supplied about 66 mg of caffeine. Traditional gourd preparation uses far more leaf, such as 87.5 g per 500 mL gourd in one trial, so caffeine per day can be much higher.
Chlorogenic acids, rutin and saponins
Mate is rich in hydroxycinnamic acids (caffeoylquinic and dicaffeoylquinic acids, together called chlorogenic acids) and contains the flavonoid rutin and triterpenic saponins. Three 3 g cups supplied about 666 mg of polyphenols a day in one trial, and the extract in the 12 week body fat trial was standardized to 35 mg of chlorogenic acid per gram.
Adrenaline and fat use during exercise
In trained cyclists, 5 g a day of mate for 5 days raised resting plasma adrenaline, and higher fat use during low to moderate exercise tracked with blood glycerol, a marker of fat breakdown. The time trial gain did not line up with fuel use at high effort, so the authors could not tie it to fat metabolism.
Lower iron absorption from a meal
In a randomized crossover study, drinking 200 mL of mate infusion with a meal containing 11.4 mg of iron lowered the rise in blood iron over the next 4 hours compared with water. The study was done in people with an iron overload condition, so the size of the effect in other people is not known.
Clinical trials
Randomized, double blind, placebo controlled trial of a spray dried yerba mate water extract standardized to 35 mg of chlorogenic acid per gram, 3 g a day in capsules (Kim et al. 2015, BMC Complement Altern Med)
30 Korean adults with a BMI of 25 to 35 and a high waist to hip ratio, 15 per group; 25 finished. Participants kept their usual diets.
Body fat mass (P=0.036), percent body fat (P=0.030) and waist to hip ratio (P=0.004) fell compared with placebo. Blood lipids did not differ significantly between groups, and safety blood tests and vital signs stayed within normal ranges; one participant stopped because of side effects.
Randomized trial of 1 L a day of brewed yerba mate, green tea or apple tea (control) for 8 weeks; participants could not be blinded, but the researchers analyzing samples were (Balsan et al. 2019, Nutr J)
142 men and women aged 35 to 60 with overweight or obesity and untreated high blood lipids. The mate group brewed two 500 mL gourds a day, each with 87.5 g of leaf; a mate company supplied the kits.
Serum PON-1 rose 9.7% with mate (p=0.005), a significantly different change from green tea and apple tea (p=0.036), and the rise was associated with higher HDL cholesterol. Green tea did not change PON-1 or leptin.
Randomized trial comparing 1 L a day of mate tea, a dietary intervention, or both for 90 days (Boaventura et al. 2012, Nutrition)
74 adults with high blood lipids.
Serum antioxidant capacity (FRAP) and reduced glutathione rose in all three groups, including diet alone without mate. PON-1, lipid hydroperoxides and protein carbonyls did not change. The authors concluded mate raised antioxidant protection independently of diet.
Randomized, controlled crossover trial of three daily cups of mate (3 g of roasted leaf each, about 66 mg caffeine a day) versus a caffeine-free isotonic drink, 8 weeks each; the title says blind, but the methods describe it as open label, with brand labels removed from the tea bags (Bravo et al. 2025, Mol Nutr Food Res)
52 normal weight adults (BMI 20 to 25) aged 18 to 55 who did not usually drink mate: 25 with normal cholesterol and 27 with high cholesterol not on statins.
Blood pressure and inflammatory cytokines fell after mate. LDL cholesterol fell in the normal cholesterol group, but in the high cholesterol group the control drink lowered lipids similarly. Body weight and circumferences did not change; percent body fat fell only in the normal cholesterol group.
Double blind, placebo controlled, randomized crossover study of 2 g of ground green yerba mate leaf in capsules taken before a 2 hour rest and 30 minutes of moderate cycling (Alkhatib et al. 2017, Nutrients)
12 healthy, active women.
Fat oxidation during exercise was higher with mate (0.21 versus 0.17 g per minute, p<0.05). Hunger, prospective eating and desire to eat ratings were lower, and self-rated focus, energy and concentration were higher (p<0.05). This was a single-dose test.
Double blind crossover trial of 5 g of yerba mate or maltodextrin placebo a day for 5 days and 1 hour before testing (Areta et al. 2018, Med Sci Sports Exerc)
11 well-trained male cyclists (9 completed the time trial).
Mate raised resting adrenaline and fat use by 23% at 30 to 50% of maximal oxygen uptake. Time trial performance improved slightly (29.4 versus 30.1 minutes, P=0.0278), but this was unrelated to fuel use at high effort.
Single blind trial of 330 mL of green or roasted yerba mate infusion three times a day for 40 days, with results compared with each group's own baseline (de Morais et al. 2009, J Agric Food Chem)
102 adults: 15 with normal lipids, 57 with high lipids and 30 with high cholesterol on long-term statins.
LDL cholesterol fell 8.7% in the normal lipid group and 8.6% in the high lipid group after 40 days, and HDL rose 4.4% after 20 days in the high lipid group. Triglycerides did not change. There was no placebo group.
Randomized, controlled crossover study of 200 mL of yerba mate leaf infusion or water taken with a meal containing 11.4 mg of iron, a week apart (Pagliosa et al. 2021, Food Funct)
14 adults aged 29 to 69 with HFE hereditary hemochromatosis on maintenance therapy.
The rise in serum iron over 4 hours after the meal was significantly smaller with mate than with water. No adverse effects were seen.