Mate is a plant native to South America. It is widely consumed as a hot beverage known as chimarrão, and is also used in traditional medicine. Mate is valued for its stimulatory effects and promoted as a dietary supplement for weight loss, cardiovascular diseases, and cancer prevention.

In vitro studies indicate that mate has antioxidant ⁽¹⁾ and cardioprotective properties  ⁽²⁾. Animal models also suggest antiadipogenic and antilipidemic effects ^(3) (4).

Studies in humans are limited. One product containing mate was found to delay gastric emptying in overweight patients ⁽⁵⁾, and other preliminary studies in generally healthy women suggest consumption may have short-term effects on caloric intake and appetite regulation ⁽⁶⁾. In a large population of heavy mate drinkers, lower lipid levels but higher bodyweight was observed ⁽³⁴⁾.

In a small cross-sectional study, long-term consumption of mate tea was associated with better bone health in postmenopausal women ⁽⁷⁾, but a more recent case-control study indicates a neutral effect on bone metabolism ⁽³⁵⁾.

In various cancer models, constituents of mate exhibited proteasome ⁽⁸⁾ and topoisomerase ⁽⁹⁾ inhibitory properties, as well as anti-inflammatory and apoptotic effects ^(10) (11). However, no large-scale clinical studies have evaluated the safety and efficacy of mate in humans. Further, epidemiologic data indicate that chronic mate drinkers are at an increased risk of prostate ⁽¹²⁾, bladder ^{(13) (14) (15)}, esophageal ^(16) (17), lung ⁽¹⁸⁾, and head and neck cancers ⁽¹⁹⁾. This risk appears to be additive when combined with chronic alcohol or tobacco use ⁽²⁰⁾. Evidence also suggests that drinking very hot mate contributes to its carcinogenic effects  ⁽³³⁾, although a meta-analysis found that mate consumed at more than 1 liter daily was associated with increased odds of developing upper aerodigestive tract cancers regardless of the temperature ⁽³⁶⁾.