Posted on 10/31/2012 at 02:57:43 PM by Student BloggerBy Samuel Scott
“Every day, twice a day, I take a chunk of earth from this wall and, well, I eat it.” This statement from a woman living on a small island called Pemba off the east African coast, conveys a practice—pica, the habitual consumption of non-food items—that invoked the curiosity of book author and current Associate professor at Cornell University Dr. Sera Young during her MA research on maternal anemia in Tanzania.
In her book Craving Earth: Understanding Pica, The Urge to Eat Clay, Starch, Ice & Chalk, published in 2011, Young highlights both published and anecdotal accounts of pica using a biocultural perspective to attempt to understand this globally-ubiquitous phenomenon. After describing which groups of people practice pica and what they are eating (including a discussion on the purported healing properties of clay, the most common target of pica enthusiasts), the book proceeds with science-driven evidence-based approach to figure out why these people are behaving in such an seemingly unusual way.
Is it because they are famished and have no other source of food, because they are mentally unsound, because they are deficient in certain nutrients that clay or starch may provide (the opinion I held before reading the book), or as an unconscious behavioral strategy to defend themselves against otherwise-harmful toxins and pathogens that the clay is able to sequester?
To answer each of these questions, Young provides historical accounts—from dirt-eating slaves in the 19th century who were forced to wear metal masks by their disgusted owners, to charcoal-snatching monkeys living near human settlements in Zanzibar—as well as evidence from recent work such as her own study of 2,361 women attending antenatal clinics in Pemba, forty percent of whom engaged in pica behavior (Young et al. 2010).
Overall, it seems that the available evidence most strongly supports the hypothesis that humans (primarily women and children) engage in pica due to the healing and medicinal properties of clay and earth, which function to protect and detoxify them. But, in order to causally relate pica behavior and the protective function of consumed substances, Young stresses the need for future randomized controlled trials that may be better able to identify a physiological mechanism by which pica occurs.
Targeting multiple audiences, Craving Earth is accessible to both academics and the lay reader. The book is written clearly, moves quickly, is made visually-pleasing with photographs and figures, and contains detailed appendices with compiled data and references for the curious scientist. I strongly recommend Craving Earth to anyone who is remotely curious about pica (an eating behavior that, in my opinion, is less unusual than dressing up as monsters and eating sugar until we get sick) and would like to broaden their perspective on nutrition.
Craving Earth: Understanding Pica, The Urge to Eat Clay, Starch, Ice & Chalk. Sera L. Young. New York. Columbia University Press. 2011.
Young SL, Khalfan S, Farag T, Kavle T, Ali S, Hamad H. Pica is associated with anemia and gastrointestinal distress among pregnant Zanzibari women. American Journal of Tropical Medicine & Hygiene. 2010;83:144-51.