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if you are referring to alternative supplements there are some used to treat depression.
Some of those are 5-HTP, L-Tryptophan, B-complex vitamins and SAMe amongst others such as St. John's Worth which you have mentioned.
A wonderful book addressing diet and life style is called -
Natural Prozac: Learning to Release Your Body's Own Anti-Depressants by Joel C. Robertson (Paperback - Feb 3, 1998)