Cross‐Sectional and Longitudinal Associations Between Dietary Intake and Depressive Symptoms in Young South African Adults: The African‐PREDICT Study

Introduction

Depression is highly prevalent among young adults worldwide. While research links health behaviours, such as dietary intake, to depression, few studies have examined these associations in low‐ and middle‐income countries (LMICs), including South Africa. This study investigated whether dietary intake was associated with risk of depression in a cohort of young South African adults, aged 20–30 years, as part of the Global burden of disease Lifestyle And mental Disorder (GLAD) project.

Methods

This 5‐year prospective cohort study was conducted in the North West Province of South Africa following the GLAD project protocol (DERR1‐10.2196/65576). Dietary exposures were evaluated using three non‐consecutive 24‐h dietary recalls, measuring daily intake of food groups and nutrients defined by the GBD study. Depression outcomes were assessed at baseline ( n  = 1039) and follow‐up ( n  = 551) using the Patient Health Questionnaire (cut‐off ≥10). Logistic and Poisson regression analyses were performed, reporting odds ratios (ORs) and relative risks (RRs). Four models were tested: unadjusted, sociodemographic‐adjusted, total energy (TE) intake‐adjusted and fully adjusted (both sociodemographic and TE‐adjusted). For longitudinal analyses, baseline depression cases were additionally excluded ( n  = 403).

Results

Participants (mean age 24.55 years; 51.4% female; 48.6% Black) had a 29.45% baseline depression prevalence. Higher milk intake was associated with a lower risk of incident depression (RR = 0.94, 95% CI 0.91–0.98) in the TE‐adjusted model. Cross‐sectionally, higher sugar‐sweetened beverage consumption was associated with higher odds of depression, whereas higher calcium (OR = 0.48, 95% CI: 0.31, 0.76) and vegetable intake (OR = 0.74, 95% CI: 0.61, 0.91) were associated with lower odds after TE adjustment. Higher fibre intake was associated with lower odds in the unadjusted model.

Conclusion

Higher milk intake was associated with lower incident depression, while higher calcium, vegetable and fibre intake were associated with lower depression prevalence, but not when adjusting for sociodemographic information. These findings suggest that sociodemographic context should be considered alongside dietary strategies to support prevention efforts for common mental disorders in young adults.

Trial Registration: ClinicalTrials.gov identifier: NCT03292094