Pica is typically talked about as an eating disorder, but there isn’t a single, diagnosable cause. In some cases, people are moved to eat things that aren’t food because they suffer from major vitamin deficiencies and their bodies crave, say, the iron present in paint or the calcium they perceive to be present in chalk. If you knew a kid in school who would eat paste, it’s likely they weren’t getting the right diet at home. Indeed, there are many subsets of pica, including pagophagia (the eating of ice), trichophagia (the eating of hair), and geophagia (the eating of dirt). Hunter is afflicted mostly with acuphagia, which draws people to eat sharp objects. Pica isn’t considered an official disorder until it has persisted for at least a month.

Pica most commonly affects pregnant women, curiously, and it’s usually linked to iron deficiencies. In the film “Swallow,” however, it’s more complicated than that. Hunter is clearly uncomfortable with her new husband and his family. She feels neglected and is almost immediately abandoned in her home when she gets pregnant. Her husband is annoyed by her complaints. The pica is not an attention-getting technique, but an odd way to fill herself.

Hunter will eventually talk to a shrink about her past. It seems that she never met her biological father, who went to prison for sexually assaulting her mother and fathering Hunter against her mother’s will. Hunter, as one might intuit, feels unwanted, like she was forced on her mother, and that her father sees her as a result of criminal shame. She seems to have assumed that marrying into a rich family would surround her with warmth and purpose, but the opposite happened.

Her anxieties manifested as pica.