According to medical explanations, people suffering from xenophagia will persistently chew on non-nutritious substances such as dirt, paper, and filth. Some smaller things, such as matches and chalk, can be eliminated directly from the patient’s body, but larger things have to be removed only through surgery. In the past, it was thought that xenophagia was mainly caused by the lack of trace elements such as zinc and iron in the body. But in recent years, studies have found that it is the large amount of foreign objects swallowed by the patient that causes the impaired absorption of zinc and iron in the body. Nowadays, more and more doctors believe that the main cause of xerophagia is psychological, but there is no substantial progress on the real cause and treatment. The cause is mainly psychological, a compulsive behavior of psychological disorder, which occurs mostly in children from 1.5 to 6 years old, but there are also adults who suffer from “xenophagia”, and even animals can suffer from “xenophagia”.