The father who came to our family-medicine clinic with his young daughter seemed concerned. The girl, he said, had become a voracious consumer of books. But not in a good way. “She eats them,” he explained, describing how she tore away the pages, one by one, and put them in her mouth, munching and chewing on them.

The 6-year-old girl was otherwise normal: She was developing and growing appropriately; she had not complained of any pain; the rest of her diet was regular. Her parents were trying to get her to stop, but she simply wouldn’t. What is going on? he asked. And should he be worried? Could this habit cause harm?

The compulsion to eat what’s inedible is known in the medical world as pica (pronounced “PIE-ka”). This is the Latin word for magpie, a bird with a reputation for eating practically anything. Human magpies, according to the medical literature, have been known to eat paper, and a lot more besides: dirt, ashes, starch, matches, cardboard, hair, laundry detergent, chalk and soap, among other things.

This little girl is not alone. Many people, for reasons that are not entirely clear to scientists, eat these nonnutritive substances.

A recent study by the Agency for Healthcare Research and Quality found that hospitalizations for pica in a 10-year span jumped 93 percent, from 964 in 1999-2000 to 1,862 in 2008-2009.

It is difficult to say how common pica is, since most people don’t report it. Nearly all medical journal articles about pica call the condition “underreported” and “unrecognized.” Perhaps it is because patients fear the quizzical look and follow-up question: “You’re eating what?”

According to some studies, more than 50 percent of kids age 18 to 36 months seek and ingest non-food items. The practice is reported to decrease as a kid ages, but one study suggested that about 10 percent of children older than 12 may engage in pica.

And as common as it may be in kids, it is also an ancient practice: Reports and academic studies from antiquity describe “geophagia,” essentially, eating dirt. Dirt is, in fact, the favorite among pica eaters, especially in the United States, where the habit seems concentrated among small children and women who are native to the South, African American or pregnant.

Pica theories

Scientists and anthropologists studying pica have come up with several hypotheses about the cause of these cravings. They include stress, learned behavior, mental health issues and nutritional deficiencies (although the evidence for the last of these is not very strong). Some studies have pointed to an association between pica and deficiencies in iron, calcium, zinc and other nutrients such as thiamine, niacin and vitamins C and D. One explanation, offered in a recent article in the Quarterly Review of Biology, suggests that eating dirt may “protect the stomach against toxins, parasites, and pathogens.”

In addition to being common among young kids, many instances of pica are seen in people with developmental disabilities and autism. As a result, it is often considered a psychiatric condition. But in the absence of mental health problems, are certain forms of pica, particularly geophagy, abnormal behavior?

In 2000, a workshop on pica organized by the Agency for Toxic Substances and Disease Registry decided that the answer is no. One of the most compelling arguments was that dirt eating is far too common to be considered abnormal behavior.

The panel may also have been influenced by the work of researcher and social worker Kevin Grigsby. Grigsby studied black women in central Georgia who eat dirt, and he concluded that the phenomenon is a “culture-bound syndrome.” In other words, it’s a cultural practice, not a psychiatric illness.

In fact, it is so common in some communities that kaolin, a chalky white substance whose scientific name is aluminum silicate hydroxide, is readily available in grocery and other stores across the South, and through such online retailers as WhiteDirt.com (“Discreet Shipping on All Orders”).

An ancient practice

Grigsby is among scientists who believe pica is as ancient as the human race and practiced by cultures across the globe, often as a folk remedy for the cravings and side effects of pregnancy. From Australia to Africa, the Middle East to Mississippi, there are people, particularly women, who believe the minerals found in dirt can enhance fertility, supplement their diets and help with the nausea common in the first trimester.

Dirt also is held to have other therapeutic powers. The ancient Greeks ate it to fight a variety of ailments. It is said to relieve diarrhea and nausea. Members of a Nigerian tribe are known to make long journeys to a special area near Lake Chad to obtain “kanwa,” a certain type of soil they consume and also feed to their cattle. In many other cultures it is believed that dirt eating will correct mineral deficiencies. In the United States, a form of kaolin for years was a key ingredient in stomach-settling products such as Kaopectate.

In 1997, Canadian scientists analyzed soils in three area where geophagia is commonly practiced; one was in North Carolina, the others were in China and Zimbabwe. They found that soils in these places are rich in iodine, iron, calcium, potassium and kaolinite, from which kaolin is derived.

Dirt eating is also practiced in religious circumstances. In New Mexico, for example, more than 300,000 people visit El Santuario de Chimayo each year, drawn in part by the healing power of the soil. At this Catholic shrine, which locals call “the Lourdes of America,” a plastic spoon is used to feed supplicants soil from the hole in the ground where a small crucifix was found buried in 1810.

Health effects

Still, isn’t eating dirt bad for you? Isn’t it dangerous to eat other non-food items associated with pica?

Certainly, there are risks involved. Chalk, clay or coins can mess with a person’s gastrointestinal system, cause constipation, ulcerations, perforations and, in rare cases, even block the intestines. Dirt eating can affect iron and mineral levels in the body and expose the eater to such parasites as nematodes and hookworms, and such heavy metals as lead.

The father who came to my clinic did not know any of that; he was just worried about his daughter’s odd behavior. Still, the child seemed quite healthy and happy.

A blood draw revealed she had mild iron deficiency, but that was all. We will never know if eating the books was a result of that deficiency or the cause, or altogether unrelated. But with some behavioral intervention, and iron supplements, she has stopped.

If you find your child, or even yourself, craving non-food items:

• Know that you are not alone, and certainly not crazy.

• Report this to your doctor so that she or he can check for anema, iron deficiency, potassium levels and parastitic infections.

• Ask if you need to take any nutritional supplements.

In most cases, pica is harmless, but if this behavior falls outside the range of what’s considered normal in kids (that is, if it lasts for more than a month) or if it suddenly starts up in an older child or adult, you should notify your physician.

There are behavioral interventions that are documented to work, including teaching the patient and his/her family about the potential harms and offering such alternatives as exchanging inedible items for edible ones, delivering positive reinforcement for avoiding the behavior and correcting a child who reverts to eating dirt and other inappropriate items. In some cases, psychiatric medications have been shown to help.