Stomach Problems? Eat Dirt

According to scientists at Cornell University, eating dirt is not just the domain of curious toddlers or eccentrics and is actually a widespread practice (known as geophagy). As a phenomenon, it transcends eras and borders, according to the study's lead author, Sera Young.

Previously, scientists thought eating dirt was a response to famine, but had no nutritional value. Others thought that it was consumed because it contained nutrients such as iron, zinc or calcium.

To test the various theories, the researchers reviewed 480 cultural accounts of geophagy, and were able to dismiss the hunger hypothesis, as geophagy occurs even when food is plentiful.

The study found that people most often eat earth when their stomachs are unsettled.

Geophagy has been reported in women in the early stages of pregnancy and pre-adolescent children, both of whom are especially sensitive to parasites and pathogens. It is also most common in tropical climates where food-borne microbes are most abundant.

The authors said more research would be needed to confirm the hypothesis.

"We hope this paper stimulates [more] research," the authors write.

"More importantly, we hope readers agree that it is time to stop regarding geophagy as a bizarre, non-adaptive gustatory mistake."

"With these data, it is clear that geophagy is a widespread behaviour in humans ... that occurs during both vulnerable life stages and when facing ecological conditions that require protection."

The study is published in the June issue of The Quarterly Review of Biology.