Researchers at the University of Alabama at Birmingham were the brains behind the study. They analyzed 84 middle schoolers from low-income families in Birmingham. Tests found out high levels of sodium and low levels of potassium in the group. They also observed symptoms of depression with the children and their parents.
A year and a half later, researchers had the group tested again and observed further signs of depression. According to the researchers, high sodium is an indication of a diet containing processed foods and unhealthy snacks. The low potassium meanwhile could be due to a lack of healthy fruits and vegetables.
“High sodium, you must consider of highly processed food,” said lead creator Sylvie Mrug, chair of the psychology department at UAB.
“This incorporates cheap food, frozen meals, and unhealthy snacks.”
Low potassium, Mrug further told, is a sign of a diet that is lacking in healthy fruits and vegetables that are rich in potassium, such as beans, sweet potatoes, spinach, tomatoes, bananas, oranges, avocados, yogurt, and salmon.
The research also concluded that higher urine levels of sodium, and potassium at baseline, predicted even more symptoms of depression a year and a half later, even after adjusting for varying factors like blood pressure, weight, age, and sex.
A meta-analysis of studies from the United States, Spain, France, Australia, Greece, and Iran also concluded a “robust association” between diet and depression. Their study showed that people who refrain from a highly-processed diet and instead followed a Mediterranean diet — fresh fruits, vegetables, nuts, seeds, and little red meat or processed foods — had lesser chances of suffering from depression.
Earlier studies had indicated a link between fast food, processed baked goods, and depression in adults. One study in Spain had almost 9,000 people as samples over six years and observed a 48% higher risk of depression in those who ate more highly processed foods.