Geopolitical Fertiliser and Energy Shocks Threaten Dietary Health in Vulnerable Populations

Background: Geopolitical disruptions to energy and fertiliser markets can affect food security and health far beyond the immediate conflict zone, yet the extent of these effects across populations, and under shocks of different severity and duration, remains uncertain. We assess the potential global food security and dietary health consequences of stylised energy and nitrogen-fertiliser price shocks such as those that could follow disruption to trade through the Strait of Hormuz, a key corridor for global energy and fertiliser trade.<br><br>Methods: We use a global, spatially resolved, process-based land system model to simulate scenarios of energy and nitrogen fertiliser price shocks associated with a Strait of Hormuz crisis. Scenarios of varying shock longevity and severity are compared with a no-shock baseline. We assess changes in land use (including fertiliser use and crop productivity), food prices, and dietary intake. We estimate changes in undernourishment, and mortality attributable to dietary and weight-related risk factors using a comparative risk assessment framework.<br><br>Findings: Nitrogen fertiliser and energy price shocks reduce fertiliser use, lower crop productivity, raise food prices, and negatively impact diets and dietary health, especially under severe and persistent shocks. Land-use change occurred mainly through reallocation within agriculture rather than expansion into natural land. Sharp declines in calorie intake and dietary diversity have the greatest impact in low- and lower-middle- income countries. By 2030, prolonged disruptions increase diet-related health burdens, with scenario-dependent increases of up to approximately one million additional dietary health-related deaths and 67 million additional people entering the underweight BMI category relative to the Reference scenario. The burden of diet-related mortality is borne substantially by lower-income regions, particularly South Asia, Sub-Saharan Africa, and East Asia &amp; Pacific, but health outcomes change little in higher-income regions.<br><br>Interpretation: Health and food security impacts of geopolitical conflict disproportionately burden people in poorer and more vulnerable regions, revealing a deep inequality in the global distribution of conflict-related food system outcomes.