A positive association between high dietary medium-chain fatty acids intake and depression: Mediation of inflammation

Our aims were to investigate the association between dietary MCFAs and depression, with a focus on potential mediating factors.

A total of 11,085 participants from NHANES were included in this study. The total intake of MCFAs, including octanoic acid (C8:0), decanoic acid (C10:0), and lauric acid (C12:0), was derived, and their respective ratios to total fatty acids were calculated as exposure. Depression was defined as a score of ≥10 on the Patient Health Questionnaire-9 (PHQ-9). Weighted logistic regression was used to analyze the relationship between MCFAs and depression. The contribution of MCFAs was assessed using weighted quartile sum (WQS). C-reactive protein (CRP) was included as a potential mediator in the analysis of underlying mechanisms.

The highest quartile (Q4) of dietary MCFAs was associated with a significantly greater likelihood of depression compared to the lowest quartile (Q1) (OR_total MCFAs: 1.36, 95 % CI: 1.07-1.65; OR_C8:0: 1.46, 95 % CI: 1.15-1.77; OR_C10:0: 1.38, 95 % CI: 1.06-1.60; and OR_C12:0: 1.31, 95 % CI: 1.03-1.68), but no significant associations were observed for Q2 and Q3. The WQS results indicated that C12:0 contributed the most to the association between total MCFAs and depression (weight percentage: 49.1 %). CRP partially mediated the association between the Q4 of MCFAs and depression, with a mediation proportion of 7.6 % to 9.1 %.

Excessive intake of MCFAs is associated with a higher risk of depression, particularly for C12:0, with CRP partially mediating this association.