Dual fortification of salt with iodine and iron: a randomized, double-blind, controlled trial of micronized ferric pyrophosphate and encapsulated ferrous fumarate in southern India.

BACKGROUND: Dual fortification of salt with iodine and iron could be a sustainable approach to combating iodine and iron deficiencies. OBJECTIVE: We compared the efficacy of dual-fortified salt (DFS) made by using 2 proposed contrasting formulas-one fortifying with iron as micronized ground ferric pyrophosphate (MGFePP) and the other with iron as encapsulated ferrous fumarate (EFF)-with the efficacy of iodized salt (IS) in schoolchildren in rural southern India. DESIGN: After stability and acceptability testing, a double-blind, household-based intervention was conducted in 5-15-y-old children (n = 458) randomly assigned into 3 groups to receive IS or DFS with iron as MGFePP or EFF, both at 2 mg/g salt. We measured hemoglobin, iron status, and urinary iodine at baseline, 5 mo, and 10 mo. RESULTS: Median serum ferritin and calculated median body iron improved significantly in the 2 groups receiving iron. After 10 mo, the prevalence of anemia decreased from 16.8% to 7.7% in the MGFePP group (P < 0.05) and from 15.1% to 5.0% in the EFF group (P < 0.01). The median urinary iodine concentration increased significantly in the IS and EFF groups (P < 0.001) but not in the MGFePP group. Losses of iodine in salt with 1.8% moisture were high for MGFePP, whereas the EFF segregated in salt with 0.5% moisture and caused color changes in some local foods. CONCLUSIONS: Both DFSs were efficacious in reducing the prevalence of anemia and iron deficiency in school-age children. Local salt characteristics should be taken into consideration when choosing an iron fortificant for DFS to achieve optimal iodine stability and color.