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.
Major electronic databases were searched through March 2018 for all randomized controlled trials (RCTs) of dietary interventions reporting changes in symptoms of depression and/or anxiety in clinical and non-clinical populations. Random-effects meta-analyses were conducted to determine effect sizes (Hedges’ g with 95% confidence intervals) for dietary interventions compared to control conditions. Potential sources of heterogeneity were explored using subgroups and meta-regression analyses.
Sixteen eligible RCTs with outcome data for 45,826 participants were included; the majority of which examined samples with non-clinical depression (N=15 studies). Nonetheless, dietary interventions significantly reduced depressive symptoms (g=0.275, 95% C.I.=0.10-0.45, p=0.002). Similar effects were observed among high-quality trials (g=0.321, 95% C.I.=0.12-0.53, p=0.002), and when compared to both inactive (g=0.308, 95% C.I.=0.02-0.60, p=0.038) and active controls (g=0.174, 95% C.I.=0.01-0.34, p=0.035). No effect of dietary interventions was observed for anxiety (k=11, n=2,270, g=0.100, 95% C.I.=-0.04-0.24, p=0.148). Studies with female samples observed significantly greater benefits from dietary interventions, for symptoms of both depression and anxiety.
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.
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1 NICM Health Research Institute, Western Sydney University, Australia;
2 Division of Psychology and Mental Health, Faculty of Biology, Medicine and Health, University of Manchester, UK;
3 Deakin University, Food & Mood Centre, IMPACT Strategic Research Centre, School of Medicine, Barwon Health, Geelong, Australia
4 Baker Heart and Diabetes Institute, Metabolic and Vascular Physiology, Australia
5 Youth Mental Health Research Unit, Greater Manchester Mental Health NHS Foundation Trust, Manchester, UK
6 School of Psychiatry, Faculty of Medicine, UNSW Sydney, Australia;
7 Keeping the Body in Mind Program, South Eastern Sydney Local Health District, Sydney, Australia;
8 University of Padua, Neurosciences Department, Padua, Italy
9 Padua University Hospital, Psychiatry Unit, Padua, Italy
10 Physiotherapy Department, South London and Maudsley NHS Foundation Trust, London, United Kingdom
11 Department of Psychological Medicine, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
12 Post Graduate Program in Health and Human Development, La Salle University, Canoas, Brazil;
13 Hospital de Clínicas de Porto Alegre, Federal University of Rio Grande do Sul, Porto Alegre, Brazil;
14 Department of Psychiatry, University of Toronto, Toronto, ON, Canada;
15 Centre for Addiction and Mental Health (CAMH), Toronto, ON, Canada;
16 Black Dog Institute, Sydney, Australia
17Murdoch Childrens Research Institute, Centre for Adolescent Health, Melbourne, Australia
18Department of Psychiatry, University of Melbourne, Professorial Unit, The Melbourne Clinic, Melbourne, Australia.
Corresponding author: Joseph Firth, NICM Health Research Unit, University of Western Sydney, Penrith, NSW 2750, Australia. Tel: +44 (0)161 306 7914. Email: email@example.com
Co-final author (Felice Jacka and Jerome Sarris)
Funding and Conflict of Interests
JF is supported by a Blackmores Institute Fellowship. WM is funded by a Deakin University Dean’s Postdoctoral Research Fellowship. FNJ is supported by an NHMRC Career Development Fellowship (2) (APP1108125). JS is funded by an NHMRC Research Fellowship (APP1125000). ST is funded by the South Eastern Sydney Local Health District in a clinical position. BS is supported by the Health Education England and the National Institute for Health Research HEE/ NIHR ICA Programme Clinical Lectureship (ICA-CL-2017-03-001). The views expressed in this publication are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health and Social Care. Felice Jacka has received Grant/Research support from the Brain and Behaviour Research Institute, the National Health and Medical Research Council (NHMRC), Australian Rotary Health, the Geelong Medical Research Foundation, the Ian Potter Foundation, Eli Lilly, Meat and Livestock Australia, Woolworths Limited, The Fernwood Foundation, The Wilson Foundation, GMHBA and The University of Melbourne and has received speakers honoraria from Sanofi-Synthelabo, Janssen Cilag, Servier, Pfizer, Health Ed, Network Nutrition, Angelini Farmaceutica, Eli Lilly and Metagenics. J.Sarris has received either presentation honoraria, travel support, clinical trial grants, book royalties, or independent consultancy payments from: Integria Healthcare & MediHerb, Pfizer, Scius Health, Key Pharmaceuticals, Taki Mai, Bioceuticals & Blackmores, Soho-Flordis, Healthworld, HealthEd, HealthMasters, Kantar Consulting, Research Reviews, Elsevier, Chaminade University, International Society for Affective Disorders, Complementary Medicines Australia, SPRIM, Terry White Chemists, ANS, Society for Medicinal Plant and Natural Product Research, Sanofi-Aventis, Omega-3 Centre, the National Health and Medical Research Council, CR Roper Fellowship.
Registration: PROSPERO online protocol: CRD42018091256.