Nutritional Deficiencies and Clinical Correlates in First-Episode Psychosis: A Systematic Review and Meta-analysis

Objective: Diet is increasingly recognised as a potentially modifiable factor influencing the onset and outcomes of psychiatric disorders. Whereas, previous research has shown long-term schizophrenia is associated with various nutritional deficiencies, this meta-analysis aimed to determine the prevalence and extent of nutritional deficits in first-episode psychosis (FEP).
Method: A search of electronic databases conducted in July 2017 identified 28 eligible studies, examining blood levels of six vitamins and ten minerals across 2,612 individuals: 1,221 individuals with FEP and 1,391 control subjects. Meta-analyses compared nutrient levels in FEP to non-psychiatric controls. Clinical correlates of nutritional status in patient samples were systematically reviewed.
Results: Significantly lower blood levels of folate (N=6, n=827, g=-0.624, 95% C.I.=-1.176 to -0.072, p=0.027) and vitamin D (N=7, n=906, g=-1.055, 95% C.I.=-1.99 to -0.119, p=0.027) were found in FEP compared to healthy controls. Synthesis of clinical correlates found both folate and vitamin D held significant inverse relationships with psychiatric symptoms in FEP. There was also limited evidence for serum level reductions of vitamin C (N=2, n=96, g=-2.207, 95% C.I.=-3.71 to -0.71, p=0.004). No differences were found for other vitamins or minerals.
Conclusions: Deficits in vitamin D and folate previously observed in long-term schizophrenia appear to exist from illness onset, and are associated with worse symptomology. Further research must examine the direction and nature of these relationships (i.e. mediator, moderator, or marker) with clinical status in FEP. Future trials assessing efficacy of nutrient supplementation in FEP samples should consider targeting and stratifying for baseline deficiency.