I'd like to briefly draw your attention to the results - systematic review and meta-analysis results - published by Joseph Firth and colleagues  observing that "certain vitamin and mineral supplements may reduce psychiatric symptoms in some people with schizophrenia" and specifically that certain B vitamins might be something to consider.
Such results come from a research team who are making significant waves in the field of meta-analyses and systematic reviews for all manner of different [important] topics. The additional inclusion of one Jerome Sarris to the authorship team adds a 'nutritional medicine as mainstream in psychiatry' touch to proceedings.
Drawing on data from 18 clinical trials - randomized controlled trials (RCTs) - cumulatively including over 800 participants, researchers reported that: "vitamin B supplementation (including B6, B8 and B12) reduced psychiatric symptoms significantly more than control conditions." Dose seemed to be important (higher doses appeared to be more effective than lower doses) as did timing of vitamin 'intervention'. Authors also indicated that subgroups of people with schizophrenia might be 'better responders' to this type of intervention, suggesting that either individual genetic differences or possibly nutritional deficiency before intervention might count in terms of effectiveness of B vitamin use. I was wondering whether those last points might tie into other discussions on this blog referencing genotype, B vitamins and [some] schizophrenia (see here).
In the context of the rise and rise of plurality in psychiatry ('the schizophrenias' and 'schizophrenia does not exist: discuss') there are some important research directions to be followed on the basis of the Firth findings. Identifying those people on the schizophrenia spectrum who might be potential best responders to this type of nutritional intervention is a research priority. Closely followed by further investigations on the hows-and-whys of such intervention potentially being useful. In that final respect, the peer-reviewed literature has already provided a few ideas for starters (see here and see here for examples).
To close, "I've got a good idea..."
 Firth J. et al. The effects of vitamin and mineral supplementation on symptoms of schizophrenia: a systematic review and meta-analysis. Psychological Medicine. 2017. Feb 16.
Firth J, Stubbs B, Sarris J, Rosenbaum S, Teasdale S, Berk M, & Yung AR (2017). The effects of vitamin and mineral supplementation on symptoms of schizophrenia: a systematic review and meta-analysis. Psychological medicine, 1-13 PMID: 28202095