Yerba Mate

Ilex paraguariensis

Ilex paraguariensis (yerba mate) is a South American evergreen in the holly family that is native to Brazil, Paraguay, Uruguay and parts of Argentina. The yerba mate tree can grow to a height of 20 meters in the wild, though it is usually pruned to a height of between 4 and 8 meters on commercial farms (Raintree.com 2010). The leaves are about 7-11 cm in length and 3-5.5 cm across, and are green and ovate with a serrated margin and a leathery consistency. The flowers are a pale greenish white with four to five petals, and bear small red berries about 4-6mm in diameter (about the size of a small pea) containing 4 seeds apiece (Natural History Museum 2012)

Mate trees thrive in altitudes of between 1500 and 2000 feet above sea level, and can be found growing wild near streams and rivers in central South America. Ilex paraguariensis is now farmed commercially in tropical countries around the world to meet the growing global demand for mate tea (NHM 2012, Raintree.com 2010).

TRADITIONAL USE: Native peoples of Paraguay and Brazil such as the Tupi and Guarani have traditionally collected yerba mate’s leathery green leaves in the wild to make into a tea with stimulating effects. While there is little to no archaeological evidence for the antiquity of mate tea consumption, the records of Spanish explorers and missionaries who arrived in central South America in the 1500s indicate that yerba mate tea was already a popular beverage among indigenous peoples of Paraguay and Brazil.

Spanish explorer Juan de Solís, when he first visited the La Plata river basin of Paraguay, reported that the Guarani people there drank a tea which “produced exhilaration and relief from fatigue”. He wasn’t the only European observer to remark on yerba mate’s refreshing and energizing properties: around the same time, Jesuit missionaries tried mate tea offered them by indigenous groups, and as a result started the first Ilex paraguariensis plantations to export yerba mate back to Spain and the rest of Europe (Raintree.com 2010).

TRADITIONAL PREPARATION: Yerba mate is a popular energizing drink in South America, comparable to black tea or coffee in North America and Europe (Raintree.com 2010, Sanders 2012). Although the trees are now mostly farmed on large plantations, some people still make a living as mate wildcrafters, called yerbateros or sometimes tarrafeiros in Spanish. Stands of wild mate trees still grow in humid depressions in the foothills of Paraguay and Brazil, and are said to yield a taste that is distinct from plantation-farmed trees. Harvesting is done between May and October when the trees are in leaf, and an individual tree is only harvested for its leaves once every three years in order to protect the plant. Even so, mate wildcrafting can be highly productive: a single Ilex paraguariensis tree can yield up to 30-40 kilograms of dried leaf annually (Raintree.com 2010)!

There are a couple common methods of drying and curing Ilex paraguariensis leaves into a consumable product. In the first method, the entire cut branch of a yerba mate tree is held over an open fire, which cures the leaves and causes them to become brittle while retaining their green color. The leaves are then stripped from the branch and air dried to finish them. Fire-cured yerba mate tea is said to have a distinct smoky flavor (Raintree.com 2010). Alternatively, yerba mate leaves are blanched in boiling water to soften the leathery texture and then roasted, either in a large pan over an open fire or in brick ovens, to create a finished brown leaf mate tea (Raintree.com 2010).

Although it can be enjoyed in a cup or pot like black tea, the traditional way to drink yerba mate is from a bowl made from a dried gourd, fitted with a filter to catch the tea leaves and a metal straw called a bombilla (Spanish) or a bomba (Portuguese) to draw up the hot liquid. This method of consuming Ilex paraguariensis is probably centuries old, and is reflected in that the Spanish word for Ilex paraguariensis tea, mate, also means gourd (Sanders 2012). Mate aficionados all over South America (and now in bars worldwide) drink yerba mate either hot or iced, plain or flavored with ingredients such as lemon juice, burnt sugar, or milk (Sanders 2012).

MEDICINAL USE: Due to its moderate caffeine content, Ilex paraguariensis tea is used medicinally as a diuretic and stimulant to alleviate mental and physical fatigue. Brazilian herbalists also recommend yerba mate tea to treat depression, as an analgesic to treat nerve pain and headache, and as a herbal tonic to stimulate the central nervous system, the heart, and the immune system (Raintree.com 2010). The tea has also traditionally been taken as an appetite suppressant and a purgative for cleansing the blood and bowels and improving gastric function. Finally, yerba mate leaves may also be used topically in a poultice to treat anthrax ulcers, for which the leaves may be effective due to their high tannin content (Raintree.com 2010).

Clinical research has substantiated many of the health claims associated with Ilex paraguariensis to some degree, including one of the tea’s most popular uses in Europe and North America as a fat-burning weight loss aid, especially for obesity. Clinical research has discovered that Ilex paraguariensis is thermogenic, increasing metabolism and raising body temperature in people who consume it (Brasesco et al 2011). Further clinical research in humans have shown that Ilex paraguariensis lowers harmful LDL (low-density lipoprotein) cholesterol and has a synergistic effect with statin drugs used to control cholesterol levels. Ilex paraguariensis has also demonstrated additional weight-reducing activity in mice and rat models, cell-protecting anti-oxidant activity in humans, and anti-inflammatory action in animal models (Brasesco et al 2011).

In addition to caffeine, Ilex paraguariensis contains theophylline and theobromine, two documented antioxidants also found in green tea (Camellia sinensis) and dark chocolate (Theobroma cacao) respectively (Duke, 1983). Bioassays have also revealed that yerba mate may contain a unique class of saponins called matesaponins that have been found to stimulate the immune system (Raintree.com 2010), lending further credence to yerba mate’s traditional use as a herbal health tonic. The caffeine content in yerba mate may also explain why it is effective in treating headache, due to caffeine’s vasodilating properties (Brasesco et al 2011).

As Ilex paraguariensis gained in popularity as a herbal supplement, concerns surfaced in the medical community that yerba mate consumption might be associated with increased risk of oral cancers (Loria et al 2009, Sewram et al 2003). A number of studies conducted on yerba mate consumption both in a traditional context and in herbal supplements have since suggested that this elevated cancer risk may be strongly correlated with drinking high temperature infusions of yerba mate tea (Sewram et al 2003). Consuming liquids at high temperature has been shown to subject the lining of the esophagus and gastric epithelium to thermal stress, which causes the cells to adapt to the chronic injury by changing to a cell type more equipped to cope with the stressor (a process called metaplasia) (Loria et al 2009). Although cell metaplasia isn’t a direct cause of cellular dysplasia and cancer, the correlation is strong enough to suggest that the thermal stress associated with consuming high temperature liquids, rather than the chemical profile of Ilex paraguariensis itself, is a likely cause of squamous cell cancer in subjects who consumed traditionally prepared mate tea in these studies (Loria et al 2009).

TRADITIONAL EFFECTS: Much like coffee or black tea, Ilex paraguariensis tea produces stimulation due to its caffeine content. By weight, yerba mate leaves contain between 0.7-2% caffeine, an amount comparable to coffee (at 1-2.5%) and somewhat less than unprepared black tea leaves (2.5-4.5%). However, the average six-ounce preparation of yerba mate tea contains between 50-100 milligrams of caffeine, slightly more than prepared black tea with 10-60 mg of caffeine and in the same range as coffee with 100-250 mg caffeine (Raintree.com 2010). The theophylline and theobromine also present in Ilex paraguariensis leaves counter the stimulant effect of the caffeine somewhat and can have calming and mood-elevating effects of their own (Raintree.com 2010).

Though it is still an obscure beverage worldwide relative to coffee and black tea, the stimulating, energizing and healthful effects of yerba mate suggest that this South American holly is only going to increase in popularity in the global market. One day soon, Ilex paraguariensis may join the ranks of superfoods such as açai, mangosteen, and hemp oil as a simple, readily available food with the potential to improve health and wellness for consumers worldwide.

REFERENCES

Bracesco N, AG Sanchez, V Contreras, T Menini, and A Gugliucci. “Recent Advances on Ilex paraguariensis research: minireview”, Journal of Ethnopharmacology 136 (3): 378-84, July 14th, 2011.

Duke, James A. “Handbook of Energy Crops” 1983. Unpublished.
http://www.hort.purdue.edu/newcrop/duke_energy/camellia_sinensis.html.
http://www.hort.purdue.edu/newcrop/duke_energy/theobroma_cacao.html.

“Ilex paraguariensis (yerba maté): Taxonomy”, The Natural History Museum, last modified 2012, http://www.nhm.ac.uk/nature-online/species-of-the-day/biodiversity/economic-impact/ilex-paraguariensis/taxonomy/index.html

Loria, D, E Barrios and R Zanetti, “Cancer and Yerba Maté consumption: a review of possible associations”, Pan-American Journal of Public Health 25 (6), June 2009.

Sanders, Kerry, “Next time you’re in Argentina, try a cup of mate”, Today: Where in the World, MSNBC.com, accessed April 17th, 2012, http://today.msnbc.msn.com/id/24315283/ns/today-where_in_the_world/t/next-time-youre-argentina-try-cup-mate/#.T43D4RxuE4R

Sewram V., E. De Stefani, P. Brennan, and P. Boffetta, “Maté consumption and the risk of squamous cell esophageal cancer in Uruguay”, Cancer Epidemiol Biomarkers Preview 12 (6): 508-13, June 2003.

“Tropical Plant Database: YERBA MATE- Ilex Paraguariensis”, Raintree.com, last modified March 20th, 2010, http://www.rain-tree.com/yerbamate.htm.