According to a new study from the University of Alabama at Birmingham, teens who consume foods with high levels of sodium and low levels of potassium are more likely to develop symptoms of depression. The study, published in Physiological Reports, suggests that diet is a modifiable risk factor for adolescent depression.

"Depression among adolescents in the United States has increased by 30 percent over the last decade, and we wanted to know why," said Sylvie Mrug, PhD, chair of the UAB Department of Psychology. "Very little research has been conducted on diet and depression. Our study shows the need to pay attention to what our children are eating."

During the study, urban, low-income, mostly African American adolescents self-reported their depressive symptoms at baseline and a year and a half later in addition to overnight urine collection to measure potassium and sodium levels.

The study showed that the effects of high sodium and low potassium on symptoms of depression build up over time. The unique combination of high sodium and low potassium best predicted an increase in adolescent depression.

According to researchers, health care providers can use urinary sodium and potassium as biomarkers of risk for subsequent development of depression in adolescents.

"Interventions are needed to ensure adolescents are receiving proper nutrition to decrease their risk of depression," Mrug said. "Food such as fruits, vegetables and yogurt contain low of levels of sodium and high amounts of potassium and should be encouraged as part of a teen's daily diet."