I use the term “nutraceuticals” loosely to signify vitamins, minerals, essential fatty acids and other compounds that the body cannot make (and must get from the food supply); compounds that are synthesized by the body but are in short supply, so that supplements are helpful (CoQ10 is a good example); and extracts from various herbs.
I have been using nutraceuticals in my private practice of psychiatry since 1975 (which was two years after I had completed my Psychiatric Residency, at the Payne Whitney Psychiatric Center of New York Hospital–Cornell Medical Center, on Manhattan’s East Side). The reason I turned to nutraceuticals whenever possible is that prescription medications can have such devastating side effects. I was happy to hear the expression “If your only tool is a hammer, then everything looks like nails”.
There are literally thousands of journal articles documenting that one or another nutraceutical can be therapeutic, for one or another psychiatric disorder. It is beyond the scope of this web page to go into a detailed analysis of that literature. But for the skeptics out there, and also for people who are open to the concept and would like to learn more on the subject, I highly recommend your obtaining the following reference: Sarris J et al. Adjunctive Nutraceuticals for Depression: A Systematic Review and Meta-Analysis. Am J Psychiatry 173:6, June 2016.