Can orthomolecular medicine help with schizophrenia?

Yes. Functional medicine is similar to orthomed. Some people with schizophrenia have mutations with methylation (like mthfr gene mutation). These defects completely throw off balanced production and elimination of important neurochemicals. Supplementation with methylb12, activated folate (folic acid) (5mthf), b6... In the right person can produce dramatic results. Quest or labcorp can run mthfr for $110...
Yes. The work by carl pfeiffer, md and abraham hoffer, md on pyrrole disorder, zinc deficiency, copper excess and disorders of methylation have in conjunction with pharmacotherapy been very useful in aiding persons with schizophrenia, depression, and bipolar disorder, as well as autism and adhd. One needs to approach treatment from a functional or integrative perspective to realize the full benefits.
No good evidence. Scientific studies do not support its efficacy for schizophrenia.