Soil Consumed by Chacma Baboons is Low in Bioavailable Iron and High in Clay
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Despite widespread consumption of soil among animals, the role of geophagy in health maintenance remains an enigma. It has been hypothesized that animals consume soil for supplementation of minerals and protection against toxins. Most studies determine only the total elemental composition of soil, which may not reflect the amount of minerals available to the consumer. Our aim was to test these hypotheses by evaluating the bioavailability of iron in soil consumed by chacma baboons, using a technique that simulates digestion and adsorption. Our results indicate that, despite variation in absolute iron concentration of soil samples, actual iron bioavailability was low while clay content was quite high. This suggests that iron supplementation is unlikely to be the primary motivation for geophagy in this population, and that detoxification is a plausible explanation. This study demonstrates that more research on bioavailability and clay composition is needed to determine the role geophagy plays in health maintenance.
KeywordsGeophagy Iron absorption Caco-2 cells Nonhuman primates
We acknowledge Mary Bodis and Pei-Pei Chang for assistance with laboratory analyses. PAP thanks Jennifer Giddy, the executive director of Wildcliff Nature Reserve and CapeNature for the opportunity to conduct research in South Africa, Wilderness Wildlife Trust, and the Cooperation Research Program of Primate Research Institute, Kyoto University, for financial support. She further thanks Jeannine McManus and Kate Muller of Landmark Foundation for support in the field. SLY was supported by NIH K01MH09902. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Mental Health or the National Institutes of Health. SLY was supported by the Thrasher Research Fund.
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