Kayapo

The Kayapo (Portuguese: Caiapó [kajaˈpɔ]) people are an indigenous people in Brazil, living over a vast area across the states of Pará and Mato Grosso, south of the Amazon River and along the Xingu River and its tributaries. This location has given rise to the tribe's nickname of "the Xingu". They are one of the various subgroups of the great Mebêngôkre nation (meaning "people from the water's source"). The name Kayapo is used by neighboring groups rather than referring by the Kayapo to themselves; they refer to outsiders as Poanjos.

A type of sweet potato/tuber forms an important part of the Kayapó diet, and is sometimes named "caiapo", after the tribe. It is cultivated under that name in Japan, and has been found to decrease insulin resistance in type 2 diabetic patients.