Supplementation-induced increase in circulating omega-3 serum levels is not associated with a reduction in depressive symptoms: Results from the MooDFOOD depression prevention trial

Background: There is ambiguity on how omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are associated with depression, and what the temporality of the association might be. The present study aimed to examine whether (intervention-induced changes in) n-3 PUFA levels were associated with (changes in) depressive symptoms. Methods: Baseline, 6- and 12-month follow-up data on 682 overweight and subclinically depressed persons from four European countries that participated in the MooDFOOD depression prevention randomized controlled trial were used. Participants were allocated to four intervention groups: (a) placebos, (b) placebos and food-related behavioral activation therapy (F-BA), (c) multinutrient supplements (fish oil and multivitamin), and (d) multinutrient supplements and F-BA. Depressive symptoms were measured using the inventory of depressive symptomatology. PUFA levels (µmol/L) were measured using gas chromatography. Analyses were adjusted for sociodemographics, lifestyle, and somatic health. Results: Increases in n-3 PUFA, docosahexaenoic acid, and eicosapentaenoic acid levels over time were significantly larger in the supplement groups than in placebo groups. Change in PUFA levels was not significantly associated with the change in depressive symptoms (β =.002, SE = 0.003, p =.39; β =.003, SE = 0.005, p =.64; β =.005, SE = 0.005, p =.29; β = −.0002, SE = 0.0004, p =.69). Baseline PUFA levels did not modify the intervention effects on depressive symptoms. Conclusions: In overweight and subclinical depressed persons, multinutrient supplements led to significant increases in n-3 PUFA levels over time, which were not associated with changes in depressive symptoms. Multinutrient supplements do not seem to be an effective preventive strategy in lowering depressive symptoms over time in these at-risk groups.