Researchers enrolled 184 children with mild iodine deficiency into a placebo-controlled double-blind trial on iodine supplementation. The children were between 10 and 13 years old and received either 150 mcg of iodine per day or a placebo. Children were tested before and after supplementation on measures of brain (cognitive) function, including tests of picture concepts, matrix reasoning, letter-number sequencing, and symbol search.
After 28 weeks, the children who received iodine supplements had significantly greater improvements in the picture concepts and matrix-reasoning tests compared with the children receiving placebo (no iodine). No improvements in letter-number sequencing and symbol search tests were noted. The children who had received iodine supplements also showed significant increases in iodine levels, as measured by urine and blood tests.
This research is encouraging, because the children studied were past the period of rapid brain development that occurs early in life. This suggests that even if iodine supplements are provided relatively late in the childhood development period, it still can benefit children with mild deficiency. It is always better to prevent deficiency or correct it in infancy and early childhood, but for many children “better late than never” is true for addressing iodine deficiency.
While many people in the US are not aware of iodine deficiency as a public health problem, the numbers are sobering. Globally, about 2 billion people have insufficient iodine intake for good health. The hardest hit areas are South Asia and sub-Saharan Africa, but about 50% of Europeans are iodine deficient too. Even in the US, iodine intake has fallen in recent years, putting more people at risk for deficiency.
Infants and children suffer the greatest harm from iodine deficiency. When pregnant women don’t get enough iodine, their children may be born with serious health problems, including a condition called cretinism, which is characterized by stunted physical growth and mental retardation.
In the US, iodized salt is the best source of iodine. But many people are eating less salt for other health reasons. In these cases the best bet for getting enough iodine may be a multivitamin and mineral supplement. Check the label to make sure yours contains iodine.
Other sources of iodine include seafood, sea vegetables, and seaweed. A 3-ounce portion of ocean fish, such as haddock, can provide about 325 mcg of iodine. This is more than twice the recommended intake of 150 mcg for all people 14 years and older. Flaked seaweed seasoning products can provide iodine as well.
If you have concerns about how much iodine you and your children are getting, talk to your doctor about ways to get more of this vital mineral into your diet.
(Am J Clin Nutr 2009;90:1264–71; Endocr Rev 2009;30:376–408)