Associations between fruit and vegetable (FV) consumption and mental health are suggested, largely from observational studies. This systematic review aimed to identify and summarise all published controlled intervention studies investigating the effects of FV consumption on mental health in adults. Four academic databases (Medline, PsycINFO, PubMed, Web of Science) were searched on 16 September 2022, over all years, for studies that used an intervention design; included FV consumption; included an appropriate non-FV-consumption control; used a validated measure of mental health and were conducted in healthy adults or adults with solely a depressive or anxiety-related condition. Study details were tabulated and combined using meta-analyses. Risk of bias was assessed using the domains of the Cochrane Collaboration. Six studies, enrolling 691 healthy adults and reporting on one or more mental health outcomes, were found. Meta-analyses found small and imprecise effects of FV consumption for: psychological well-being (4 studies, 289 participants) standardised mean difference (SMD) = 0·07 (95 % CI -0·17, 0·30), P = 0·58, I2 = 0 %; depressive symptomology (3 studies, 271 participants) SMD = -0·15 (95 % CI -0·40, 0·10), P = 0·23, I2 = 47 % and anxiety-related symptomology (4 studies, 298 participants) SMD = -0·15 (95 % CI -0·39, 0·08), P = 0·20, I2 = 71 %. Some benefit for psychological well-being was found in change-from-baseline data: SMD = 0·28 (95 % CI 0·05, 0·52), P = 0·02, I2 = 0 %. Risk of bias was high in many studies. Limitations include the consideration only of published studies and stem from the studies found. Given the few, limited studies available and the small size of effects, stronger evidence is needed before recommending FV consumption for mental health.
Keywords: Adults; Fruit and vegetables; Mental health; Meta-analyses; Psychological well-being; Systematic review.