Pica is the craving and eating of nonfood items. It can develop in any person but seems to be most often experienced by African American women (data is limited) in the pregnancy and postpartum period. In the southern United States, 16 to 57 percent of pregnant African-American women admit to pica. It is also generally more common in persons with severe impairments and mental retardation, although there is no connection whatsoever between the latter and the former.
It also commonly affects very young children and children with mental retardation but this can be a normal type of experimentation, as infants and toddlers tend to explore the worlds through taste and smell and often put things in their mouths. Only if the child eats inedible substances for a period of one month or longer is it considered a serious problem (or possible serious problem). Besides mental impairment, poor stimulation and little supervision in the home are distinguishing characteristics of children who develop the disorder.
In children, the habit usually begins during infancy and lasts for several months before going away on its own, with additional stimulation to the infant. For children with intellectual disabilities, it may continue into adolescence before gradually diminishing.
Items craved are such substances as clay, chalk, cornstarch, ice, hair, insects, and, unusually, paint, cigarette butts, and air-freshener blocks. Milk of magnesia, coffee grounds, plaster, and paraffin have also been reported.
Clay is the most common craving in pica and clay eating is called geophagy. This is common among the peoples of Africa and is done to curb hunger and to help with irritation from intestinal parasites and other medical reasons, as well as for spiritual purposes.
There are many suggested causes of pica but its true origin is unknown. One theory is that it reflects a need for minerals or other nutrients, but this theory is not likely to be relevant since it is unclear that humans reliably “crave” food with certain nutrients based on nutritional needs, and cravings are probably based on psychological needs. Another theory is that pica is related to obsessive-compulsive disorder (OCD).
During the 18th and 19th centuries, young girls were often encouraged to eat lime, coal, vinegar, and chalk, as these were believed to cause the pale complexion that was considered attractive at the time. Other cultural underpinnings in various societies have been observed.
Iron Deficiency and Pica
The only human mineral deficiency that is known to cause significant cravings for certain items is iron deficiency. However, the cravings are not for iron-rich foods like liver. Instead, people suffering from iron deficiency anemia crave ice, clay, and other odd things like paper. The reason this occurs is unknown.
For more information see Food and Culture by Pamela Goyan Kittler and Kathryn P. Sucher; and Abnormal Child Psychology by Eric J Mash and David A Wolfe
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