Dietary Habits May Have Protective Influence in Major Depressive Disorder

Dietary habits do not seem to be affected by major depressive disorder (MDD), but higher beef intake may be protective against MDD, according to study findings published recently in Journal of Affective Disorders.

Researchers conducted a 2-sample Mendelian randomization (MR) analysis of genome-wide, publicly available association study summary statistics from the Psychiatric Genomics Consortium (N=142,646) for MDD and the UK Biobank (N=449,210) for dietary habits. They synthesized MR estimates across genetic instruments using a weighted median approach. Weighted median results were then compared with inverse-variance weighted results, the weighted mode, and MR-PRESSO for robustness.

The estimated single nucleotide polymorphisms-based heritability of dietary habits and the prudent dietary pattern ranged from 0.025 to 0.088. Added salt, alcohol intake frequency, and hot drink temperature had a positive genetic correlation with MDD. There was some evidence of a negative genetic correlation with MDD and the intake of cheese, lamb or mutton, cereal, and dried and fresh fruit. Rather than indicating a causal relationship, the researchers believe these genetic correlations are more likely due to pleiotropy.

There was moderate evidence in the weighted median MR analysis for a causally protective effect on MDD with beef intake. The researchers noted weak evidence for a protective effect on MDD with cereal, and a possible increase in risk for MDD with nonoily fish intake. There was no causal effect of MDD on dietary habits.

The MR-PRESSO global test was used to detect horizontal pleiotropy, which showed 3 outliers in the MR effect of beef intake on MDD. Distortion in the causal estimates for beef intake on MDD was not significant as per the MR-PRESSO distortion test.

Limitations of the study include the MR study design, assumption violation leading to bias estimates, unaccounted for variance across sex and age groups of diet on MDD, and the retrospective collection of dietary habit information.

Study authors concluded, “[W]e observed higher intake of beef and cereal may be protective against MDD, and that higher nonoily fish intake might increase the risk for MDD.”

Disclosure: One study author declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.