Iodized Oil Supplementation During Infancy

In iodine-deficient countries or regions that have inadequate iodized salt distribution, WHO recommends choosing one of two methods to improve iodine intakes in breastfeeding infants:

Method 1) iodine supplement (400 mg as iodized oil; 1/year) to the breastfeeding mother Method 2) iodine supplement (100 mg as iodized oil; 1/year) directly to the infant

However, the relative efficacy of these two methods of providing iodine to the newborn has never been directly compared. Whether the first method of iodine supplementation to the breast feeding mother can significantly improve iodine supply and maintain normal thyroid function in her infant remains unclear.

The mountains of southern Morocco are areas of iodine deficiency. Although the government has been promoting iodization of salt, there are hundreds of small salt producers in the mountains who do not have the funding or infrastructure to iodize their salt, and thus many rural populations still are consuming non-iodized locally-produced salt. At the study site, a 2009 pilot survey of urinary iodine has found that the population in this region is moderately iodine sufficient.

Thus, according to WHO, breastfeeding women and/or their infants should be provided with oral iodine supplementation. But which of the above supplementation methods is preferable? Controlled studies clearly demonstrate that iodine repletion in moderate-to severely iodine deficient school-age children increases insulin-like growth factor (IGF)-1 and insulin-like growth factor binding protein (IGFBP)-3 concentrations and improves somatic growth (height and weight). But whether supplying adequate iodine to iodine deficient infants improves their somatic growth has not been tested.