Yerba mate is an infusion prepared from the leaves of yerba mate plant (South American holly tree), Ilex paraguariensis, and is the South American equivalent of our tea or coffee. The infusion, often called simply mate, is especially popular in Argentina, Paraguay, Uruguay, Brazil, and also in some Middle East countries, mainly Syria and Lebanon.
Yerba mate tea is brewed in, and also drunk from, a vessel made of the fruit of the gourd (bottle calabash) and is also called the gourd. A much higher proportion of dry matter is used than in the making of normal tea. The gourd is filled up to 2/3 with leaves and twigs before it is topped up with hot water. Water can be added many times and the infusion is drunk directly from the gourd through a filtered straw known as a bombilla.
In its native land yerba mate is exceptionally popular and its properties highly regarded. People carrying gourds with bombillas and hot water flasks for brewing are seen at work places, on the streets and in nearly all public spaces. Mate is thought to be good for warm, humid weather. Cold mate, known as terere, is ideal for hot weather.
There are claims that mate infusion might have carcinogenic properties. However, the results of studies are ambiguous. The only clear correlation that has been shown to exist is that between the custom of drinking very hot liquids (such as yerba mate, coffee or tea) and the higher incidence of cancer of the upper digestive tract.