JMIR Publications

ABSTRACT

Background:

Depression, a multifaceted disorder impairing functioning, is a leading global cause of disability, with its burden to worsen by 2030 (WHO). University students are highly vulnerable: 15.6% of U.S. undergraduates, 24.71% of Chinese college students (rising), and a meta-analysis reports a 30.6% weighted mean prevalence. Severe cases increase self-harm risks and rank fourth among adolescent deaths.Inflammation drives depression, and diet—modifiable—regulates inflammation: anti-inflammatory diets (e.g., Mediterranean) mitigate risk, while pro-inflammatory Western diets exacerbate it. The Dietary Inflammatory Index (DII) quantifies this potential.Prior studies on DII and student depression lack cohort evidence, rely on cross-sectional designs (missing long-term trends), and use error-prone recall methods. A Shanghai university’s 2020-launched Intelligent Ordering System (IOS), with validated long-term meal data, supports this study.

Objective:

This study aimed to investigate the longitudinal association between the Dietary Inflammatory Index (DII) and the incidence of depressive symptoms among Chinese university students, and to explore potential subgroup differences in this association.

Methods:

A three-year prospective cohort study was conducted among 5,314 university students from a university in Shanghai. Dietary data were collected continuously from April 2020 to March 2023 using the Intelligent Ordering System (IOS), and DII scores were calculated to quantify dietary inflammatory potential. Depressive symptoms were assessed annually from March 2021 to March 2023 using the Beck Depression Inventory-II (BDI-II). Mixed-effects logistic regression was used to analyze the association between DII and depressive symptoms, with subgroup analyses stratified by family relationship and socioeconomic status.

Results:

The baseline prevalence of depressive symptoms was 10.75% (females: 11.36%; males: 10.09%). After adjusting for covariates, compared with the highest DII quartile (most pro-inflammatory diet), lower DII quartiles (more anti-inflammatory or low pro-inflammatory diets) were associated with a reduced risk of depressive symptoms: Q1 (OR: 0.73, 95%CI:0.54–0.98), Q2 (OR: 0.62, 95%CI: 0.48–0.80), and Q3 (OR: 0.67, 95%CI: 0.53–0.85). Subgroup analyses showed that this protective effect was significant only among students with harmonious family relationships and non-poverty-stricken students, but not among those with disharmonious family relationships or poverty-stricken students.

Conclusions:

Adherence to an anti-inflammatory or low pro-inflammatory diet is associated with a lower incidence of depressive symptoms in Chinese university students. However, the protective effect is weakened in students facing familial discordance or socioeconomic deprivation, highlighting the need to integrate dietary interventions with psychosocial support.