Sources of Dietary Fiber Are Differently Associated with Prevalence of Depression

Dietary fiber has been actively studied for its profound impacts on mental health by affecting the gut-brain axis communication. However, the association between dietary fiber intake and depression has been inconsistent, partly due to the lack of consideration of the fiber source. Therefore, this study aimed to examine the association between various sources of dietary fiber and depression in Korean adults through a nationwide cross-sectional study. The study population was a total of 2960 adults between 19 and 64 years of age who participated in the Korean National Health and Nutrition Examination Survey (KNHANES, 2012-2016). Dietary fiber intake from each fiber subtype (crude, cereal, vegetable, fruit, seaweed, and mushroom) was calculated using the Food Frequency Questionnaire (FFQ). Depression prevalence was assessed using a Patient Health Questionnaire (PHQ-9) and self-reported clinical diagnosis by a physician. We found that seaweed (odds ratio (OR) = 0.38; 95% confidence interval (CI): 0.20-0.72; p < 0.05) and mushroom fiber intake (OR = 0.18; 95% CI: 0.01-0.37; p < 0.05) were inversely associated with depressive symptoms assessed using the PHQ-9 parameters. Moreover, seaweed fiber intake was inversely associated with clinical depression diagnosed by a physician (OR = 0.45; 95% CI: 0.23-0.88; p < 0.05). This was the first study to find that higher intakes of seaweed and mushroom fiber were associated with a lower likelihood of depression in a representative cohort of Korean adults, indicating that the specific source of dietary fiber may be an important dietary factor in modulating depression.