pica

Reader's Digest 2月号の記事 'Is This Normal or Nuts?' からの引用です。
The disire to eat nonfood items, including sand, coffee grounds, matches, and mothballs, is called pica, which webmd.com defines as "the persistent eating of substances...that have no nutritional value." It's most common in children and pregnant women. The cause is not clear, but "some of it is the body looking for nutrients," perhaps triggered by a metabolic disorder, says psychiatrist Dr. Reiss.
"pica" の意味は文中に説明があるので分かりますが、こんな単語があるのですね。一応辞書の説明も見ます。
・Oxford English Dictionary: A tendency or craving to eat substances other than normal food (such as clay, plaster, or ashes), occurring during childhood or pregnancy, or as a symptom of disease.: Rarely, a person with iron-deficiency anemia may experience pica, a craving to eat nonfood items such as paint chips, chalk, or dirt.
・Wiktionary: (medicine) A disorder characterized by craving and appetite for non-edible substances, such as ice, clay, chalk, dirt, or sand.
Etymology: From Latin pīca ‎(“magpie, jay”‎) (from the idea that magpies will eat almost anything).