Objective: Poor diet can be detrimental to mental health. However, the overall evidence for the effects of dietary interventions on mood and mental well-being has yet to be assessed. We conducted a systematic review and meta-analysis examining effects of dietary interventions on symptoms of depression and anxiety. Methods: Major electronic databases were searched through March 2018 for all randomized controlled trials of dietary interventions reporting changes in symptoms of depression and/or anxiety in clinical and nonclinical populations. Random-effects meta-analyses were conducted to determine effect sizes (Hedges' g with 95% confidence intervals [CI]) for dietary interventions compared with control conditions. Potential sources of heterogeneity were explored using subgroups and meta-regression analyses. Results: Sixteen eligible randomized controlled trials (published in English) with outcome data for 45,826 participants were included; the majority of which examined samples with nonclinical depression (n = 15 studies). Nonetheless, dietary interventions significantly reduced depressive symptoms (g = 0.275, 95% CI = 0.10 to 0.45, p = .002). Similar effects were observed among high-quality trials (g = 0.321, 95% CI = 0.12 to 0.53, p = .002) and when compared with both inactive (g = 0.308, 95% CI = 0.02 to 0.60, p = .038) and active controls (g = 0.174, 95% CI = 0.01 to 0.34, p = .035). No effect of dietary interventions was observed for anxiety (k = 11, n = 2270, g = 0.100, 95% CI = −0.04 to 0.24, p = .148). Studies with female samples observed significantly greater benefits from dietary interventions, for symptoms of both depression and anxiety. Conclusions: Dietary interventions hold promise as a novel intervention for reducing symptoms of depression across the population. Future research is required to determine the specific components of dietary interventions that improve mental health, explore underlying mechanisms, and establish effective schemes for delivering these interventions in clinical and public health settings. Registration: PROSPERO Online Protocol: CRD42018091256.

Background: Severe mental illness (SMI) is thought to be associated with lower diet quality and adverse eating behaviours contributing towards physical health disparities. A rigorous review of the studies looking at dietary intake in psychotic disorders and bipolar disorder is lacking.Aims: To conduct a systematic, comprehensive evaluation of the published research on dietary intake in psychotic disorders and bipolar disorder.Method: Six electronic databases were searched for studies reporting on dietary intakes in psychotic disorders and bipolar disorder. Dietary-assessment methods, and dietary intakes, were systematically reviewed. Where possible, data was pooled for meta-analysis and compared with healthy controls.Results: In total, 58 eligible studies were identified. People with SMI were found to have significantly higher dietary energy (mean difference 1332 kJ, 95% CI 487–2178 kJ/day, P = 0.002, g = 0.463) and sodium (mean difference 322 mg, 95% CI 174–490 mg, P < 0.001, g = 0.414) intake compared with controls. Qualitative synthesis suggested that higher energy and sodium intakes were associated with poorer diet quality and eating patterns.Conclusions: These dietary components should be key targets for preventative interventions to improve weight and other physical health outcomes in people with SMI.Declaration of interest: S.B.T. and E.T. have clinical dietitian appointments within the South Eastern Sydney Local Health District and do not receive any further funding.

Background: Nutrition interventions would appear fundamental for weight management and cardiometabolic risk reduction in people experiencing severe mental illness (SMI). Comprehensive evaluation of nutrition interventions is lacking.Aims: To subject randomised controlled trials of nutrition interventions in people with SMI to systematic review and meta-analysis, and to measure anthropometric and biochemical parameters and nutritional intake.Method: An electronic database search identified trials with nutrition intervention components. Trials were pooled for meta-analysis. Meta-regression analyses were performed on anthropometric moderators.Results: Interventions led to significant weight loss (19 studies), reduced body mass index (17 studies), decreased waist circumference (10 studies) and lower blood glucose levels (5 studies). Dietitian-led interventions (6 studies) and studies delivered at antipsychotic initiation (4 studies) had larger effect sizes.Conclusions: Evidence supports nutrition interventions as standard care in preventing and treating weight gain among people experiencing SMI.