Fiber intake and fiber intervention in depression and anxiety: a systematic review and meta-analysis of observational studies and randomized controlled trials

Hajara Aslam; Mojtaba Lotfaliany; Daniel So; Kirsten Berding; Michael Berk; Tetyana Rocks; Meghan Hockey; Felice N Jacka; Wolfgang Marx; John F Cryan; Heidi M Staudacher

doi:10.1093/nutrit/nuad143

Fiber intake and fiber intervention in depression and anxiety: a systematic review and meta-analysis of observational studies and randomized controlled trials

Nutr Rev. 2023 Nov 25:nuad143. doi: 10.1093/nutrit/nuad143. Online ahead of print.

Authors

Hajara Aslam¹, Mojtaba Lotfaliany², Daniel So³, Kirsten Berding⁴, Michael Berk^{1

5

6

7

8}, Tetyana Rocks¹, Meghan Hockey¹, Felice N Jacka^{1

9

10}, Wolfgang Marx¹, John F Cryan^{5

11}, Heidi M Staudacher¹

Affiliations

¹ The Institute for Mental and Physical Health and Clinical Translation (IMPACT), Food & Mood Centre, School of Medicine and Barwon Health, Deakin University, Geelong, Victoria, Australia.
² IMPACT, School of Medicine and Barwon Health, Deakin University, Geelong, Victoria, Australia.
³ Department of Gastroenterology, Central Clinical School, Monash University, Melbourne, Victoria, Australia.
⁴ APC Microbiome Ireland, University College Cork, Cork, Ireland.
⁵ School of Medicine, Deakin University, Geelong, Victoria, Australia.
⁶ Orygen, The National Centre of Excellence in Youth Mental Health, Parkville, Victoria, Australia.
⁷ Centre for Youth Mental Health, Florey Institute for Neuroscience and Mental Health, The University of Melbourne, Parkville, Victoria, Australia.
⁸ Department of Psychiatry, The University of Melbourne, Victoria, Australia.
⁹ Centre for Adolescent Health, Murdoch Children's Research Institute, Melbourne, Victoria, Australia.
¹⁰ College of Public Health, Medical & Veterinary Sciences, James Cook University, Townsville, Queensland, Australia.
¹¹ Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland.

PMID: 38007616
DOI: 10.1093/nutrit/nuad143

Abstract

Context: Dietary fibers hold potential to influence depressive and anxiety outcomes by modulating the microbiota-gut-brain axis, which is increasingly recognized as an underlying factor in mental health maintenance.

Objective: Evidence for the effects of fibers on depressive and anxiety outcomes remains unclear. To this end, a systematic literature review and a meta-analysis were conducted that included observational studies and randomized controlled trials (RCTs).

Data sources: The PubMed, Embase, CENTRAL, CINAHL, and PsychINFO databases were searched for eligible studies.

Data extraction: Study screening and risk-of-bias assessment were conducted by 2 independent reviewers.

Data analysis: Meta-analyses via random effects models were performed to examine the (1) association between fiber intake and depressive and anxiety outcomes in observational studies, and (2) effect of fiber intervention on depressive and anxiety outcomes compared with placebo in RCTs. A total of 181 405 participants were included in 23 observational studies. In cross-sectional studies, an inverse association was observed between fiber intake and depressive (Cohen's d effect size [d]: -0.11; 95% confidence interval [CI]: -0.16, -0.05) and anxiety (d = -0.25; 95%CI, -0.38, -0.12) outcomes. In longitudinal studies, there was an inverse association between fiber intake and depressive outcomes (d = -0.07; 95%CI, -0.11, -0.04). In total, 740 participants were included in 10 RCTs, all of whom used fiber supplements. Of note, only 1 RCT included individuals with a clinical diagnosis of depression. No difference was found between fiber supplementation and placebo for depressive (d = -0.47; 95%CI, -1.26, 0.31) or anxiety (d = -0.30; 95%CI, -0.67, 0.07) outcomes.

Conclusion: Although observational data suggest a potential benefit for higher fiber intake for depressive and anxiety outcomes, evidence from current RCTs does not support fiber supplementation for improving depressive or anxiety outcomes. More research, including RCTs in clinical populations and using a broad range of fibers, is needed.

Systematic review registration: PROSPERO registration no. CRD42021274898.

Keywords: anxiety; depression; dietary fiber; gut microbiota; prebiotics.