(P07-028-25) A Meta-Analysis of the Effects of Fortification of Salt With Multiple Nutrients on Health Outcomes in Children, Adolescents and Adults

Objectives: Nutritional deficiencies are prevalent in populations across the world, particularly in women, adolescents, and children living in low- and middle-income countries. Fortification of staple foods has been used as a scalable and effective alternative to supplementation to address many of the deficiencies. One such staple is salt, which has long been fortified with iodine, but more recently with iron, folate, and other micronutrients. Our primary objective was to summarize the effects of double and multiple fortified salts on hemoglobin concentration (Hb) and other nutritional and health outcomes among children, adolescents, and adults.

Methods: We conducted a systematic review of published and unpublished literature in MEDLINE (Ovid), Embase (Ovid), CINAHL (EBSCO), Cochrane Central Register of Controlled Trials (CENTRAL), and ProQuest using a pre-defined search strategy. Abstracts and full texts were screened for randomized trials, quasi-randomized trials, and program effectiveness evaluations of double or multiple fortified salt. We calculated weighted pooled effect sizes for effects of different types of salt on Hb and other outcomes.

Results: Of the 544 studies identified, 31 fit our inclusion criteria. Of these, 23 studied the effects of salt fortified with iron and iodine (DFS), two studied the effects of salt fortified with folic acid and iodine (FIFSA), one studied the effect of triple-fortified salt (TFS), one studied the effect of quadruple-fortified salt (QFS), and five studied the effects of multiple micronutrient fortified salt (MMFS). The majority (74%) of the studies were based in India. Most  DFS, MMFS, TFS, and QFS studies measured Hb as an outcome and pooled effect sizes indicated positive effects [standardized mean difference (95% CI): for DFS: 0.35 (0.21, 0.49), N=25 comparisons; for MMFS: 0.36 (0.20, 0.53), N=4; for TFS: 1.56 (0.15, 2.96), N=1; for QFS: 0.33 (0.02, 0.63), N= 1].

Conclusions: Fortification of salt with iodine and iron, with and without other nutrients, is effective in increasing hemoglobin concentrations. Further research is needed to explore the effectiveness of triple, quadruple and multiple fortified salt on nutritional as well as functional health outcomes.

Funding Sources: The Bill & Melinda Gates Foundation and the Iodine Global Network