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FALL 2011
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Dirt: The Cure for What Ails You?

By Krishna Ramanujan

Birds do it, dogs do it, even some humans do it—eat dirt that is—but until recently no one knew why. Reports of humans eating dirt, especially, have puzzled biologists for hundreds of years. Yet Sera Young, PhD ’08, research scientist in nutritional sciences, and Paul Sherman, professor of neurobiology and behavior, may have found the answer. They have concluded that humans eat dirt—technically called geophagy—to protect themselves from dietary chemicals, parasites, and pathogens.

Previous explanations have included hunger or the need to acquire such nutrients as iron, zinc, or calcium. But Young and Sherman found that people who eat dirt do so only in small amounts, often when food is plentiful and the need for nutrients is not a motivating factor.

The researchers discovered that geophagy takes place most often among pregnant women and children in tropical areas where pathogens thrive. It is also more common when toxic substances have been ingested and people are suffering from gastrointestinal distress. In other words, in some cultures, people eat dirt when their tummies hurt: They search out specific soils they consider to be clean and safe. The dirt is also typically carefully prepared and even heated before ingesting.


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