Why is Our Nation’s Intelligence Dropping?

Iodine Deficiency

Is our Nation’s intelligence dropping? Casual conversation says it is. The CNN newsroom says it is. According to CNN IQ scores have been steadily falling for decades and it is due to environmental, not genetic, factors as once thought. Environmental can be nutrition such as iodine, education, pollution or what not, but it is an environmental influence impacting this decline.


Let’s look at iodine, for example. If sufficient iodine is not consumed even marginally by pregnant women, the cognitive status of the infant can be affected. Now, in general, the US has adequate supplies of iodine as compared to other parts of the world where iodine deficiency is a prevalent problem. The problem with high risk populations such as pregnant women or even children, the requirements may not meet the intake, especially in pockets of impoverished iodine intake.

The iodine requirements of pregnant women increase from 150 µg to 220 µg in pregnancy and then again to 290 µg in breastfeeding. Iodine is an essential component of thyroid hormone, which is necessary for maturation of the central nervous system, thermogenesis, metabolism and cognitive functioning/learning. The fetus is totally dependent on maternal supplies of thyroxine for brain development due to its underdeveloped organs so any deficiency in this time period can affect cognitive status of the newborn.

In North America iodine is obtained from dairy, seafood and salt fortification.

Only about 70% of consumers use iodized salt and sodium obtained from processed foods is not iodized. Only 15% of iodine comes from natural foods in the diet and of the people who buy iodized salt only about 50 µg of iodine would come from a diet containing 5 grams of added iodized salt per day. Now, most women take prenatals vitamins and should take one every day, but of 19 supplements listed in the Physicians’ Desk Reference as prenatal vitamins had the recommended 150 µg of iodine in them.

Recent data suggests that 44% of the breastmilk samples were inadequate in iodine and deemed insufficient to meet the infant’s needs. We generally recommend that women continue to take their prenatal vitamins throughout breastfeeding so whether this was a variable or not is unknown.

According to a recent World Health Organization UNICEF conference, an opinion of experts was noted that the optimum iodine intake for pregnancy and lactation should be 225-375 µg/day.

The American Thyroid Association recommends that all prenatal vitamins contain at least 150 µg of iodine per day and that this is a safe and necessary level to assure optimum birth outcomes until additional outcome data is available.