A very interesting study from the University College London in the UK followed 3,486 people for five years. At the end of five years, they matched their depression to their diet.
They found that the most depressed individuals consumed "processed food" (heavily loaded by sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products). In contrast, the least depressed people consumed a diet of "whole foods" (heavily loaded by vegetables, fruits and fish).
Depression is a surprisingly common symptom. Before you turn to pharmaceutical antidepressants, start with changing your foods. If you eat a healthy diet your depression may subside. I strongly encourage you to take a good hard look at your diet – the best and most effective way is to write a food/mood diary and begin to notice any trends that appear. How did you feel an hour after you ate that coffee and banana bread this morning?
I always see improvements in mood when processed nutrient-poor food is removed and replaced with whole, organic and nutrient rich food.