Protocol for a community-based, household-randomised, dose-response trial to assess the acceptability, nutritional effects and safety of double-fortified salt containing iodine and folic acid compared with iodised salt among non-pregnant Ethiopian women of reproductive age (DFS-IoFA).

INTRODUCTION

The prevalence of neural tube defects (NTDs) is higher in Ethiopia than most other countries, and ~84% of Ethiopian women of reproductive age (WRA) have folate insufficiency, a major risk factor for NTDs. Salt fortification with folic acid is a potential strategy to improve women's folate status, but data are needed on the acceptability, nutritional impact and safety of folic acid fortification of iodised salt.

METHODS AND ANALYSIS

The study is designed as a community-based, household-randomised, dose-response trial. A total of 360 non-pregnant WRA 18-49 years of age will be randomly assigned to one of three intervention arms: (1) iodised salt fortified with 30 ppm folic acid to provide ~200 µg folic acid/day; (2) iodised salt fortified with 90 ppm folic acid to provide ~600 µg folic acid/day; or (3) iodised salt (comparator). The preweighed salts will be delivered to participants' homes biweekly for 26 weeks; unused salt will be collected and weighed. Fasting, venous blood samples will be collected at baseline, end line and a randomly assigned intermediate time point for assessment of folate, iodine, vitamin B and other micronutrient status biomarkers. Women's dietary intakes, including discretionary salt consumption, will be measured using weighed food records; 24-hour urine specimens will be analysed for sodium and iodine excretion. Primary outcomes are women's consumption of study salts, change in biomarkers of folate and iodine status and prevalence of adverse events. Results will be analysed using analysis of covariance models to estimate group mean differences for continuous outcomes, controlling for baseline measurements, and log-binomial or modified Poisson regressions for categorical outcomes. Prespecified effect modifications will be explored.

ETHICS AND DISSEMINATION

The study has been approved by the Ethiopian Public Health Institute's Institutional Review Board, and the protocol has been registered with ClinicalTrials.gov (registration number NCT06223854). Study results will be published in open access scientific journals and disseminated nationally in Ethiopia.

TRIAL REGISTRATION NUMBER

NCT06223854.