INTRODUCTION:
Food insecurity is a persistent public health challenge in South Africa. While it is widely understood to contribute to poor mental health and exacerbate chronic conditions, the relationship may also be bidirectional. This study examines the prevalence of food insecurity and its bidirectional relationships with mental health and comorbidities.

METHODS:
We analyzed nationally representative data from 3,095 South African adults aged 16 years or older in 2025. Household food insecurity was measured using a single-item question. Mental illness, diabetes, and hypertension were based on respondents’ self-reported professional diagnoses. As a sensitivity analysis, we also examined a self-rated mental health measure. Prevalence estimates, bivariate associations, and multivariable regression models were used to examine sociodemographic predictors of food insecurity and its associations with these conditions. A generalised structural equation model (GSEM) was used to assess bidirectional relationships with mental health and the comorbidities of hypertension and diabetes. Statistical significance was set at p < 0.05.

RESULTS:
Overall, 37.4% (95% CI: 34.5–40.5) of adults reported household food insecurity. Mental illness showed a strong independent association with food insecurity (PR = 2.31; 95% CI: 1.42–3.75), and sensitivity analyses yielded consistent results. The GSEM further demonstrated that socioeconomic status was the strongest predictor of food insecurity and identified a reciprocal association between food insecurity and mental illness.

CONCLUSIONS:
These findings highlight the urgent need for integrated policy responses that address structural inequities, positioning food insecurity reduction as a core component of South Africa’s broader public mental health strategy.