Income-health related behaviour thresholds and stress-contingent effects on willingness to pay for safe and nutritious food among smallholder farmers in Southwest, Nigeria

In resource-constrained agrarian economies, the demand-side barriers to safe and nutritious food remain critically understudied. This study investigates the behavioural-economic determinants of smallholder farmers’ willingness to pay (WTP) for safe and nutritious food in Southwest Nigeria, integrating insights from the Bandwidth Tax Model and Dual-System Decision Theory. Using a multi-stage stratified sample of 294 farmers, we identify a pivotal income threshold (₦79,220.37/month: €1=₦1,690.90) below which health-related behaviour (HRB) fails to influence WTP (B = 0.529, p = 0.041), validating nonlinear income-behaviour dynamics. Poverty-induced stress significantly suppresses WTP (B = −45.383, p = 0.001), while market information asymmetry exacerbates quality-conscious purchasing barriers (Exp(B) = 0.002–0.009). Consistent with theoretical and empirical evidence, social networks (B = 13.379, p = 0.038) and education (B = 0.059, p = 0.032) significantly enhanced willingness to pay (WTP). These findings challenge conventional supply-side food security policies, demonstrating that cognitive load from financial scarcity and stress distorts rational food choices. The framework prioritizes leveraging social networks and education programmes to amplify impact. We propose a tripartite policy framework: (1) income-sensitive interventions, (2) stress-mitigation strategies, and (3) nudge-based market reforms. By bridging behavioural science and agricultural economics, this study advances scalable solutions for SDGs 2 and 3, offering a paradigm shift in addressing the malnutrition-food safety nexus in low-income agrarian settings.