The foundations of orthomolecular psychiatry. Nutrient treatment of the anxiety, depression and psychosis in scurvy and pellagra. Dr Abram Hoffer’s niacin and vitamin C megavitamin therapy for schizophrenia. Dr Carl Pfeiffer’s histamine axis biotypes. The research on pyrrole disorder.  Dr William Walsh’s methylation imbalances and applications to bipolar, autism, violence, etc.  Nutritional psychiatry continues to evolve through the work of many noted researchers. 
Suggested books: Adventures in Psychiatry by Abram Hoffer
https://www.orthomolecular.org/library/jom/1974/pdf/1974-v03n04-p223.pdf