Stevia is a shrub that is native to South America. The leaves of the stevia plant have been used for centuries by the Guaranà people of Paraguay and Brazil to sweeten teas and medicinal concoctions. The plant was first introduced to Westerners in the early 1900s by Swiss botanist Moises Santiago Bertoni, who was studying the indigenous people of Paraguay. In the 1970s, Japanese chemists isolated the compounds in stevia that are responsible for its sweetness, and the product began to be used as a sugar substitute in Japan.