After looking at factors such as gender, age, education, physical activity, smoking habits and chronic diseases, they found a significant difference in future depression risk with the different diets. In fact, those who ate the most whole foods had a 26% lower risk of future depression than those who at the least whole foods. By contrast people with a diet high in processed food had a 58% higher risk of depression than those who ate very few processed foods.
The research is concluding what so many people seem to already know, that what we eat can affect our mood, making us feel happier.