Geophagia, also known as geophagy, is the intentional practice of eating earth or soil-like substances such as clay, chalk, or termite mounds. It is a behavioral adaptation that occurs in many non-human animals and has been documented in more than 100 primate species. Geophagy in non-human primates is primarily used for protection from parasites, to provide mineral supplements, and to help metabolize toxic compounds from leaves. Geophagy also occurs in humans and is most commonly reported among children and pregnant women. Although its etiology remains unknown, geophagy has many potential adaptive health benefits as well as negative consequences.

Source: Wikipedia