Fatty acid and vitamin interventions in adults with schizophrenia: a systematic review of the current evidence

Current psychopharmacological approaches to reduce psychotic phenomenology in schizophrenia are associated with adverse effects including extrapyramidal and metabolic side effects. In view of the emerging data on nutritional supplementation interventions in schizophrenia which are not entirely consistent, we aimed to review existent studies focusing on fatty acid and vitamin interventions and summarise current evidence on such nutritional supplementations in schizophrenia. We searched the digital databases (ScienceDirect, Scopus, SpringerLINK, PubMed/Medline) for relevant studies pertaining to fatty acid and vitamin supplementation interventions in the management of psychotic symptoms in schizophrenia up to February 2015. Overall, there were more studies conducted on fatty acid over vitamin supplementations in patients with schizophrenia. There were more positive findings in support of fatty acid supplementation compared with vitamin supplementation in the context of specific intervention features (dose of nutrient supplementation, single versus combination nutritional interventions, specific antipsychotic), subject features (older age, long duration of illness, baseline polyunsaturated fatty acid levels) and clinical outcomes (improvements of psychotic symptoms and/or extrapyramidal side effects from antipsychotics). However, investigations of both supplementation modalities were limited by relatively small study sample sizes, short study duration, which precluded further segmentation of impact on more diverse patient subtypes and symptom profiles. Future studies may consider examining larger samples over a longer time period, recruiting younger subjects with shorter duration of illness, examination of different clinical features including specific cognitive domains, and use of single versus combination nutritional interventions.