The Inflammatory Potential of the Diet Is Associated with Depressive Symptoms in Different Subgroups of the General Population

Abstract

Background: Low-grade chronic inflammation, which can be modulated by diet, has been suggested as an important risk factor for depression, but few studies have investigated the association between the inflammatory potential of the diet and depression.Objective: We investigated the prospective association between the inflammatory potential of the diet, measured by the Dietary Inflammatory Index (DII), and incident depressive symptoms and tested the potential modulating effect of sex, age, physical activity, and smoking status.Methods: This study included 3523 participants (aged 35-60 y) from the SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydants) cohort, who were initially free of depressive symptoms. Baseline DII (1994-1996) was computed by using repeated 24-h dietary records. Incident depressive symptoms were defined by a Center for Epidemiologic Studies-Depression Scale score ≥17 for men and ≥23 for women in 2007-2009. We used multivariable logistic regression models to estimate ORs and 95% CIs, and modeled the DII as a continuous variable and as sex-specific quartiles.Results: A total of 172 cases of incident depressive symptoms were identified over a mean follow-up of 12.6 y. The DII was not associated with incident depressive symptoms in the full sample. In sex-specific models, men with a higher DII had a higher risk of incident depressive symptoms (quartile 4 compared with quartile 1-OR: 2.32; 95% CI: 1.01, 5.35), but the association was only marginally significant (P-trend = 0.06). When analyses were performed across smoking status, current and former smokers with a higher DII had a higher risk of incident depressive symptoms (quartile 4 compared with quartile 1-OR: 2.21; 95% CI: 1.08, 4.52). A positive association was also observed among less physically active participants (quartile 4 compared with quartile 1-OR: 2.07; 95% CI: 1.05, 4.07).Conclusion: The promotion of a healthy diet with anti-inflammatory properties may help to prevent depressive symptoms, particularly among men, smokers, or physically inactive individuals. This trial was registered at clinicaltrials.gov as NCT0027242.

Trial registration: ClinicalTrials.gov NCT00272428.

Keywords: Dietary Inflammatory Index; depression; diet; inflammation; mental health; prospective study.

FIGURE 1

Flow chart of participant selection. CES-D, Center for Epidemiologic Studies–Depression Scale; DII, Dietary Inflammatory Index; SU.VI.MAX, Supplémentation en Vitamines et Minéraux Antioxydants.

FIGURE 2

Association between quartiles of DII score and incident depressive symptoms in population subgroups. P values for the interaction terms were as follows: 0.26 for age, 0.56 for physical activity, and 0.88 for smoking status. Values are ORs and 95% CIs across quartiles of the DII. Model adjusted for age, sex, intervention group during the trial phase, educational level, marital status, socio-professional status, energy intake without alcohol, number of 24-h dietary records, interval between the 2 CES-D measurements, smoking status, physical activity, and BMI (all covariates were collected at baseline). ¹Irregular physical activity or <1 h walking/d. ²Physical activity of ≥1 h walking/d. CES-D, Center for Epidemiologic Studies–Depression Scale; DII, Dietary Inflammatory Index; Q, quartile.