Orthomolecular psychiatry
Orthomolecular psychiatry is a branch of orthomolecular medicine whose proponents argue that dietary supplements and other treatments may be effective in treating mental illness.
Though mainstream medical experts agree that some nutritional and dietary supplements have value in treating mental illness (for example, through the use of omega 3 fatty acid), the sometimes sweeping claims of orthomolecular psychiatry proponents have found little support among mainstream medical experts.

# History
The origins of orthomolecular psychiatry can be traced as early as 1927.
However orthomolecular psychiatry per se is generally accepted to have begun in the 1950s with the work of Abram Hoffer and Humphry Osmond in Canada. Later proponents include  Carl Pfeiffer, David Horrobin and Linus Pauling.

# Orthomolecular psychiatry treatments and scope
Specific techniques commonly employed include individual biochemical workup, dietary measures, fasting, megavitamin therapy, and identifying allergies.
Hoffer and Osmond developed and used the "HOD test" to identify and monitor schizophrenia patients' progress, using a much different method than the testing used by the American Psychiatric Association. A more recent development in orthomolecular psychiatry applies the "niacin flush" concept dermally to identify and evaluate patients biochemically.
Many orthomolecular physicians still prescribe antipsychotics, initially. However, the long-term avoidance of neuroleptics is the main goal. Dr. Carl Pfeiffer's dictum known as "Pfeiffer's Law" states, "For every drug that benefits a patient, there is a natural substance that can achieve the same effect".
These and other methods have been claimed to treat alcoholism, drug addiction, anxiety, autism, clinical depression, hyperactivity, attention-deficit hyperactivity disorder, Alzheimer's disease, mental retardation, dementia, bipolar disorder and schizophrenia.

# Criticisms
As of 2005, orthomolecular psychiatry remains controversial, with little support among the mainstream medical community. Critics have noted that the claims of proponents are considered unsubstantiated by conventional psychiatry. Authoritative bodies such as the National Institute of Mental Health and American Academy of Pediatrics have historically criticized orthomolecular treatments as ineffective and potentially toxic.
A 1973 task force of the American Psychiatric Association charged with investigating orthomolecular claims, but instead focused on niacin monotherapeutically (the earliest version of treatment, ca. 1952) for a different kind of patient population, concluded:
This review and critique has carefully examined the literature produced by megavitamin proponents and by those who have attempted to replicate their basic and clinical work. It concludes in this regard that the credibility of the megavitamin proponents is low. Their credibility is further diminished by a consistent refusal over the past decade to perform controlled experiments and to report their new results in a scientifically acceptable fashion.
Under these circumstances this Task Force considers the massive publicity which they promulgate via radio, the lay press and popular books, using catch phrases which are really misnomers like "megavitamin therapy" and "orthomolecular treatment," to be deplorable.
According to a Beersheva Mental Health Center study begun in 2005 and ongoing as of 2007,
Controlled studies using the orthomolecular approach have been few. Those that were done were performed in chronic schizophrenia or in populations that included bipolar and schizoaffective patients. Both of these diagnostic groups are not today considered to benefit from the orthomolecular approach. Moreover, some negative studies of high-dose niacin were done in patients who were not otherwise given general counseling for good diet."; compared with a basic, modern orthomolecular regimen.
Harvard-trained pediatrician Mark Vonnegut discusses orthomolecular psychiatry in his memoir The Eden Express; he advocated the use of orthomolecular psychiatry but later disavowed it.

## Rebuttals
Proponents consider the 1973 APA task force report error laden with sweeping, scientifically unfounded conclusions, highly politicized, and that its studies failed to use similar methods, materials and subjects as the original work.  The APA report's criticism alleges inadequate controlled trials because Hoffer quit running additional blinded tests that he had come to view as unethical for his patients, especially since the results of his previous double blinded tests went unheeded.  The APA's assertion is made despite Hoffer's claim to have run the first double blind controlled test in psychiatry, on megavitamin therapies, with a total four double blinded tests, up to 19 years before the APA task force report, as well as being supported by two independent double blinded tests 
 and an extensive biochemical research program.   One of the APA report's six authors, psychologist JR Wittenborn, reacting to Hoffer's specific criticisms, later re-analyzed his original double blind study favorably with respect to orthomolecular psychiatry, obtaining the same result as Hoffer, and never received NIMH or APA support again. Wittenborn's latter report also goes unquoted by critics.  Another of the APA report's authors, then NIMH member Loren Mosher, later resigned from the American Psychiatric Association in total disgust, which he also called a "drug company patsy." 

# Scientific evidence
A recent literature review by scientists at Johns Hopkins University found that a variety of studies noted that the removal of gluten from the diet of schizophrenics showed potential as a viable therapy only in a subset of schizophrenic patients. They concluded that further research was needed to confirm this association.