This webpage has lots of information that deals with this subject with info from many sources. It has information from a book that suggests that people eat a potato before they go to bed. It explains why it works.
It has the information on a complete diet by a psychiatrist. It has information on psychiatrists using fasting for depression. It has information of the lifestyle that a minister used to cure his severe depression and anxiety.
Also it mentions things that have cured depression like omega-3 fatty acids. The principle is that a chain is only as strong as its weakest link. So it does
not matter how many things that you do right. You must make sure that nothing is being done wrong.