The effects of nutritional deficiencies usually leave an apparent toll on your body. However, a nutrient deficient diet could also be the possible cause of certain emotional disorders, most commonly linked to depression.
In the past depression was believed to be purely emotional, and biochemical based, but recent neuroscience research has proven otherwise.
Researchers actually found that poor nutritional practices can directly effect your behavior, cognition, and even cause onset depression.
Of course, if you suffer from depression, you should see your physician, get an actual diagnosis, and talk about your options.