Pica: the craving and purposive consumption of substances that the consumer does not define as food for more than a month.
Hippocrates wrote the first known account of pica around 400 BC. Pica pica was the Latin term for the magpie, a common bird thought to have an indiscriminant appetite. So pica has been used to describe non-food cravings reported around the globe for 17 centuries. You might think by now science knows all about it. Not so.
The strength of non-food cravings is often equated to cravings for addictive substances like tobacco and alcohol. Most common pica substances are earth (dirt, especially clay), raw starch (e.g. cornstarch, laundry starch*, or uncooked rice), ice, charcoal, ash, paper, chalk, baby powder, coffee grounds and eggshells. Archeological evidence suggests people have been eating this stuff for more than 2 million years in hundreds of cultures on every continent. Today the practice is common in pregnancy around the world, and in people undergoing renal dialysis, or having gluten intolerance or anemia.
A common theory is that pica is a response to iron deficiency. But no data exists that suggests pica improves low iron status, or that iron supplementation cures pica. Similarly there is no evidence to implicate calcium or zinc deficiency. There is limited evidence that makes the most likely explanation for craving dirt or cornstarch is that these and other pica substances reduce harmful effects of toxins by thickening the intestinal walls or by facilitating their removal from the gut before they enter the blood stream.
Pica remains a mystery. The best evidence supports the theory that pica protects against toxins. A few studies suggest that craving large quantities of ice may be due to iron deficiency. And eating clay or starch may lead to anemia and other micronutrient deficiencies.
What’s to be Done?
Simply telling a woman to stop eating nonfood substances is unlikely to overcome her cravings. More likely, that will cue her to conceal the behavior. Best to alert her that pica is common and should be taken as a signal to have her doctor check for iron deficiency, anemia, or micronutrient deficiency.
Beginnings Pregnancy Guide currently says & a revision for 2011: Cravings
Your tastes in food might change during pregnancy. Something you usually enjoy may suddenly taste awful. You might want some foods you rarely eat – maybe pickles and ice cream. These odd cravings are of no concern as long as you eat well otherwise.
The statement remains accurate. Since cornstarch has been found to be the most common form of raw starch eaten by U.S. mothers, “laundry starch” will be replaced by “cornstarch.
Home visitors and others who support pregnant women should be alert to pica, discuss it openly with mothers and facilitate her in seeking consultation from her prenatal care provider or a nutritionist.
Book 1 *Laundry starch is a combination of rice, corn and potato starches, primarily sold in aerosol cans
References: Young, SL. (2010). Pica in Pregnancy: New Ideas about an Old Condition. Annual Reviews of Nutrition 30: 403-422. 117 references and supplemental materials