Geochemistry and mineralogy of soils eaten by humans

Earth samples (soils and parent materials) eaten by humans on three continents were analyzed chemically and mineralogically. Samples from Changsha county, China, are from three sites and were used as recently as the 1950s as famine food; soil from a site in North Carolina, USA was consumed for general health benefits; samples from Zimbabwe are still used as medicine for digestive problems (diarrhea). In each case, it is 'common knowledge' that the geophagy is beneficial. Chemical analysis of the soils and of soil extracts, and mineralogical analysis of the soils, reveal patterns of element levels and clay minerals relatively consistent with the effects desired or reported by consumers. There are important parallels between geophagy in humans and in animals, in particular the apparent quest for dietary/nutritional and pharmaceutical benefits.