Nutritional aspects of psychiatric disorders.

As most diet therapy texts provide little information about psychiatric illnesses and their treatment, this article is intended as a brief introduction for dietitians. Several psychiatric illnesses, including schizophrenia, mood disorders, eating disorders, and substance abuse, may adversely affect food intake and nutritional status. The drugs used to treat those disorders similarly have effects on appetite and gastrointestinal function and interact with food and nutrients. Antipsychotics, antidepressants, and monoamine oxidase inhibitors (MAOIs) cause dry mouth, constipation, and weight gain. Lithium may cause nausea, vomiting, diarrhea, polydipsia, and weight gain. MAOIs have well-known interactions with foods containing tyramine. Lithium interacts with dietary sodium and caffeine; decreasing dietary intakes of those substances may produce lithium toxicity. Despite claims to the contrary, major psychiatric illnesses cannot be cured by nutritional therapies alone. Dietitians can, however, play an important role as part of a multidisciplinary team in the treatment of patients with psychiatric illness. Such a role includes nutrition assessment and monitoring, nutrition interventions, patient and staff education, and some forms of psychotherapy, including supportive and behavioral therapies for patients with eating disorders.