Causal influence of dietary habits on the risk of major depressive disorder: A diet-wide Mendelian randomization analysis

Abstract

AbstractBackground & aimsSome evidence suggests that diet may potentially increase or decrease the risk of major depressive disorder (MDD). However, the association between dietary habits and MDD remains controversial. The aim of this study is to systemically investigate the causal influence of dietary habits on the risk of MDD by Mendelian randomization (MR) using diet- and genome-wide summary data.MethodsTo perform two-sample MR, we collected publicly available genome-wide association studies’ summary statistics for dietary habits from Benjamin Neale’s lab (n = 361,194) and MDD from the Psychiatric Genomics Consortium (n = 142,646). We used a weighted median approach to synthesize MR estimates across genetic instruments. For the robustness of our results, we compared weighted median results with results from the inverse-variance weighted method, the weighted mode method, and MR-PRESSO.ResultsBeef intake showed a significant protective effect against MDD (β = -1.25; p-value = 0.002; Bonferroni-corrected p-value = 0.034; 9 single nucleotide polymorphisms [SNPs]); and cereal intake was nominally significantly protective (β = -0.52; p-value = 0.011; 21 SNPs). In contrast, non-oily fish intake showed a nominally significantly effect on the risk of MDD (β = 0.84; p-value = 0.030; 6 SNPs). We obtained similar results by using an inverse-variance weighted method and weighted mode approach, although some results were non-significant. On the other hand, we did not observe any significant causal effect of MDD on dietary habits.ConclusionsIn this two-sample MR analysis, we observed that higher beef and cereal intake may be protective factors for MDD, and that higher non-oily fish intake might increase the risk for MDD. However, MDD did not appear to affect dietary habits. Potential mechanisms need to be further investigated to support our novel findings.