I liked this excerpt that describes the subtle, supportive (and I think necessary) role food plays in mental health:
Nutritional changes aren't a magic bullet; they're subtle pieces of a treatment plan that might also include therapy, exercise--one of the most effective depression busters--and stress-reduction techniques.
But "diet can help with virtually any chronic condition" including depression, said registered dietitian Wendy Bazilian, who holds a doctorate in public health. Just remember that major depression might require an integrative approach that uses food in conjunction with other therapies, including medication and counseling. And never abruptly stop taking medication even if you're experiencing side effects such as weight gain and sexual dysfunction; talk to your doctor about tapering down.
The article also quotes a psychiatrist and author (Dr. James S Gordon), other physicians and a couple of diet book authors (including a registered dietitian) who share research findings, opinions and recommendations on foods to eat more often and foods to limit or avoid.
Link: Feel-good foods