Impacts of large-scale food fortification on the cost of nutrient-adequate diets: a modelling study in 89 countries.

Introduction: Large-scale food fortification (LSFF) is a widely accepted intervention to alleviate micronutrient deficiencies, yet policy implementation is often incomplete. Even assuming high implementation of existing mandatory and voluntary standards, the effects of LSFF on least-cost diets have not been established. Diet cost metrics such as the cost of nutrient adequacy offer insights into how policy interventions such as LSFF might change access to nutritious diets around the world. Methods: We estimated the extent to which LSFF reduces the retail cost of nutrient-adequate diets using retail food prices and fortification policy data from 89 countries. In total, we modelled 5874 complete pairs (without fortification vs with fortification) of least-cost diets across 22 sex-age groups and three nutrient-adequacy scenarios: meeting nutrient requirements only, adding minimum intakes for starchy staples and fruits and vegetables, and aligning food group shares with national consumption patterns. Single-vehicle and single-nutrient scenarios highlighted the cost reductions associated with specific fortification approaches. In addition, we used regression methods to estimate the relationship between diet cost reductions and the total quantity of nutrients added to the food supply. Results: Assuming 90% implementation of existing LSFF standards for wheat flour, maize flour, rice and oil, we found median retail cost reductions of 1.6%, 2.4% and 4.5% across the three scenarios. Cost reductions varied widely by sex-age groups, national fortification strategies and food price structures. Results from the regression analysis revealed that intermediate levels of food fortification resulted in the largest potential diet cost reductions. Conclusions: These findings highlight that LSFF may improve economic access to nutritious diets when policies are carefully designed for local contexts, making it a valuable complement to other efforts that improve access to nutritious diets.