AUTHOR=Zhang Ting , Cui Xiao-mei , Zhang Yu-ying , Xie Tao , Deng Yuan-jia , Guo Fang-xi , Wang Qi , Wu Qing-feng , Dong Ming-hua , Luo Xiao-ting TITLE=Inflammation mediated the effect of dietary fiber on depressive symptoms JOURNAL=Frontiers in Psychiatry VOLUME=13 YEAR=2023 URL=https://www.frontiersin.org/journals/psychiatry/articles/10.3389/fpsyt.2022.989492 DOI=10.3389/fpsyt.2022.989492 ISSN=1664-0640 ABSTRACT=Background and aims

Previous studies showed that inflammation affects depressive symptoms. Dietary fiber may be associated with inflammation and depressive symptoms. We aimed to investigate the relationship between inflammation and depressive symptoms at different levels of dietary fiber intake and to explore whether dietary fiber affects depression through inflammation.

Methods

A total of 8,430 National Health and Nutrition Examination Survey (NHANES) samples were collected between 2015 and 2018. Factor analysis was used to determine dietary patterns. Linear regression and logistic regression analysis were used to explore the relationship between nutrients, inflammation, and depressive symptoms, and the mediation analysis was conducted using the bootstrap method.

Results

Factor 3 (dietary fiber and vitamins) was inversely associated with depressive symptoms and inflammation. The upper quartile scores of the dietary inflammatory index (DII) and C-reactive protein (CRP) were associated with depressive symptoms compared with controls (DII: OR = 1.851, 95% CI: 1.267–2.705; CRP: OR = 1.737, 95% CI: 1.136–2.656). The DII score and CRP were associated with depressive symptoms in the group with low dietary fiber intake (DII: OR = 2.736, 95% CI: 1.628–4.598; CRP: OR = 2.092, 95% CI: 1.196–3.658) but not in the high dietary fiber intake group. Mediating analysis showed that CRP partially mediated the effect of dietary fiber intake on depressive symptoms (βindirect = −0.0025, 95% CI: −0.0038 to −0.0013), and the mediated proportion was 10.5%.

Conclusion

In this study, we found that DII scores and CRP were not associated with depressive symptoms in participants with high dietary fiber intake, and inflammation partially mediates the effect of dietary fiber on depressive symptoms.