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Tue December 4, 2012
Dr. Sera Young, Cornell University – The Urge to Eat Dirt
In today’s Academic Minute, Dr. Sera Young of Cornell University explores why some pregnant women experience a compulsion to eat odd things.
Sera Young is a research scientist in the Division of Nutritional Sciences at Cornell University. Broadly, her research seeks to understand and ameliorate the contributions of environmental and behavioral factors to poor maternal and child nutrition. More specifically, her research has focused on a behavior known as pica, in which anemic women crave earth, raw starch, and other non-food substances. She holds a Ph.D. from Cornell University.
Dr. Sera Young – The Urge to Eat Dirt
For most, the consumption of dirt is to be avoided. But to geophagists, as they’re called, eating earth is delectable, enjoyable, and even irresistible. A decade ago, in Zanzibar, Tanzania, I met my first geophagist. We were sitting in Mama Sharifa’s sunbaked yard, discussing her diet during pregnancy, when she explained how twice a day she took a small hunk of earth from the wall of her house, and ate it. Her urge mystified both her and me.
As it turns out, Mama Sharifa has plenty of company. There are hundreds of thousands of people around the world who crave earth, including right here in the United States. Geophagy is mostly associated with pregnancy and anemia, but the health consequences have been an enigma since Hippocrates.
There are two major adaptive explanations: 1) that it acts like a vitamin, to supplement missing nutrients like iron and 2) that it detoxifies harmful pathogens or chemicals, like a mud mask for the gut.
We have brought ethnographic, epidemiologic, and biochemical data to bear on geophagy in Zanzibar, and it looks as if there is more support for the detoxification hypothesis. Pregnant women who eat earth and other non-food items are more likely to be anemic, which would seem to support the “multivitamin hypothesis” but the iron in these items is not bioavailable. In fact, recent in vitro analyses suggest that earth can bind to dietary iron, which would cause anemia. But this same binding ability that keeps iron from being absorbed may also work to sequester chemicals and pathogens that are particularly harmful during pregnancy.
In effect, eating dirt might, in fact, be purifying.