The Association Between Dietary Fiber Intake and Depression Among US Adults: A Cross-Sectional Study Based on NHANES Data From 2005 to 2020.

Depression is a prevalent chronic condition that affects a person's thoughts, emotions, and physical health. However, there is limited evidence on the impact of dietary fiber on depression. Additionally, the association between dietary fiber intake and the risk of depression remains controversial. We extracted data from the National Health and Nutrition Examination Survey (NHANES) database on 85,750 participants. After excluding minors and pregnant individuals, and those with missing Patient Health Questionnaire-9 (PHQ-9) data, dietary fiber intake, or covariates, we included 29,980 participants for data analysis. Categorizing them into non-depressed groups, clinically relevant depression (CRD, with scores no less than 10) and clinically significant depression (CSD, with scores no less than 15) is determined based on PHQ-9 scores. We employed survey-weighted generalized linear models, and restricted cubic spline (RCS) curves are employed to judge the significance of the correlation of dietary fiber intake and risk of developing CRD and CSD. Finally, we conducted subgroup analyses using stratified weighted multiple regression analysis. The manuscript was organized according to STROBE guidelines. There exists a non-linear inverse relationship between dietary fiber intake and the incidence of CRD and CSD. In the model after full adjustment, compared to individuals in the first quartile, the probability of CRD was reduced by 17%, 22%, and 30% respectively for those in the second, third, and fourth quartiles (odds ratios [OR] = 0.70; 95% confidence interval [95% CI]: 0.57-0.85,  < 0.001); the risk of CSD was reduced by 22%, 40%, and 32% (OR = 0.68; 95% CI: 0.48-0.94,  = 0.02). RCS curves indicate an L-shaped nonlinear connection existing between dietary fiber consumption and both CRD and CSD. Subgroup analysis strengthens the stability of the conclusions. There is a nonlinear negative relationship of dietary fiber intake and the risk of CRD and CSD, with a nonlinear L-shaped relationship between dietary fiber intake and both CRD and CSD.