Is the association between food insecurity and depression mediated by diet?

Food insecurity (FI) is associated with negative affective states such as depression. FI involves distinctive patterns of dietary intake, and recent evidence suggests that dietary intake affects affective state. Dietary variables may therefore represent an important pathway linking FI to poor mental health. In two cross-sectional datasets (one from the UK, n = 394, and NHANES 2017-18 from the USA, n = 4011), we examined: associations between FI and affective state; between FI and dietary patterns; between dietary patterns and affective state; and the statistical mediation of the FI-affective state association by dietary patterns. In both datasets, FI was associated with a more negative affective state, greater meal irregularity, and reduced dietary diversity; lower dietary diversity was associated with a more negative affective state. Other FI-diet and diet-affective state associations were inconsistent across datasets. Dietary variables partially mediated the FI-affective state association in both datasets, accounting for 23% and 6% of the total association respectively, with dietary diversity the only individually significant mediator. These findings suggest that while reduced dietary diversity partially explains the association between FI and outcomes such as depression, neither it nor other dietary variables account for the greater part of this relationship.