What comes first, the depression or the fast food binge? Research seems to indicate the latter in adults; studies have even shown that a healthier diet can reduce depressive symptoms. A group of researchers at the University of Alabama at Birmingham theorized that this might also be true for adolescents and undertook a multiyear study of 84 teenagers to prove it.
The teens in the study all lived in Birmingham, came from low-income families, and were evenly divided between male and female; 95% were black and they were, on average, 13.36 years old when the study started. Instead of relying on the kids to self-report on the healthiness of their diets, researchers took urine samples and measured the amounts of sodium and potassium present. High levels of sodium indicated heavy consumption of salty and processed foods, while high levels of potassium indicated a diet full of fruits, vegetables, fish, and poultry. At the same time the urine was collected, the teenagers were asked to rate their level of depression on a four-point scale, with four being the most depressed. A year and a half later, the researchers collected more urine and again asked the kids how depressed they were.
It turned out the kids who had an increase in sodium in their diets also experienced in increase in depression. (The potassium levels didn’t seem to be as strong an indicator.) So there is likely something to this healthy diet business after all! The scientists aren’t sure why—gut bacteria? neurotransmitters?—so be prepared for more research.