Fortification of salt with iodine is considered to be one of the most effective means to reduce childhood undernutrition. Though there exists a strong biologic basis for a role of iodine in somatic growth failure in childhood this relationship has not been studied on a large scale yet and existing evidence shows very mixed results. We investigate if there exists a general pattern of the association between household unavailability of iodized salt and child undernutrtion across countries.
We use 87 nationally representative, repeated cross-sectional and mutually comparable Demographic and Health Surveys (DHS), conducted between 1994 and 2012 across 46 low- and middle-income countries. We analyzed the data for stunting (low height-for-age), underweight (low weight-for-age), wasting (low weight-for-height) and low birth weight in children aged between 0 and 59 months at the time of the interview. Our main variable of interest is the unavailability of iodized salt within a household. By including individual, maternal and household covariates and fixed effects on the level of the primary sampling unit we control for potential confounders.
In fully adjusted models unavailability of iodized salt was associated with 3.2 percent higher odds of being stunted (p=0.029; 95% CI: 1.003,1.062), 5.8 percent higher odds of being underweight (p=0.001; 95% CI: 1.024,1.092) and 3.6 percent higher odds of being wasted (p=0.099; 95% CI: 0.993, 1.081). However, the global association is largely driven by the India sample.
Since results are largly driven by India we can only cautiously conclude that iodized salt alone can be potentially beneficial for reducing childhood undernutrition, but that these potential benefits depend on the country context.