Preteens are known for being moody and angsty. But a new study suggests that diet could have something to do with that. According to the University of Alabama study, high levels of sodium and low levels of potassium were reported in many youngsters' diets. High sodium, you've got to think of highly processed food. This includes fast food, frozen meals and unhealthy snacks, Sylvie Mrug, Study author, via CNN. Teen diets were found to be deficient in fruits and vegetables. . Higher levels of sodium in the diet predicted higher levels of depression later in life. One study in Spain showed a 48% higher risk of depression in those who ate more processed foods.