It's hard to improve on the headline of this story:
Why chimps eat dirt
[Sabrina] Krief collected the dirt along with leaves from one of the chimps' favorite foods, the Trichilia rubescens plant. She found that when eaten alone, the leaves had no pharmacological effect, but when combined with soil, the mixture had clear anti-malarial properties.
Scientists previously suspected that animals might eat dirt when stressed or as a source of missing minerals. This new result is the first suggestion that the combination of soil and other foods could have health benefits, Krief said.
The story also discusses the use of high-kaolinite dirts as antidiarrheal treatments in local peoples -- kaolinite being the nameworthy ingredient of Kaopectate, although it is no longer used in that medication.
Anyway, this is a good excuse to use the word "geophagy." Great word.