Plant power? A systematic review of the effects of plant-based diets on people with mental illness

ObjectiveThere is increasing interest in plant-based diets in the general population and an increasing evidence base for the positive impact of plant-based diets on health outcomes for many chronic diseases. This systematic review aims to identify the effects of plant-based diets on people with mental health conditions. MethodsA systematic review of intervention and observational studies. We conducted a systematic electronic search of MEDLINE (Ovid), EMBASE (Ovid), PsycINFO (ProQuest), British Nursing Index (ProQuest), CINAHL (EBSCO) and the Cochrane library to April 2019, with no date limits. We extracted data on outcomes and assessed the studies for bias using validated tools. ResultsWe retrieved 588 studies. One study met the inclusion criteria with high risk of bias. The intervention was a plant-based diet for people with moderate to severe depression, without a control group. The study recruited 500 people, but recorded 66.8% attrition. Of the completers, 62% reported improvements in depressive symptoms, and 59% in anxiety symptoms. Completers lost 5.7lbs (2.6kg) during the trial and 15lb (6.8kg) at six month follow up. ConclusionThere is not enough research to make conclusions about the effects of plant-based diets on people with mental health conditions. Given the evidence for positive effects of plant-based diets on physical health, further research is urgently required to understand the effects on people with mental health conditions. This will support the provision of advice and guidance for patients with mental illness who want to optimise their diet to improve their mental and physical health. PROSPERO registrationCRD42019133440