Study: Iodine Salt Use May Have Increased The American IQ
ATLANTA (CBS ATLANTA) — Although iodine deficiency remains one of the world’s top causes of preventable mental retardation, many Americans don’t realize that its use has increased their IQ’s.
According to a new study from James Feyrer, Dimitra Politi and David N. Weil, Americans’ IQ has increased one full standard deviation – 15 points – since its introduction to the country in 1924.
The study found that for the one quarter of the population most deficient in iodine this intervention raised IQ by approximately one standard deviation during the time of its use. The study finds that the drug increased IQ’s nearly 3 points every decade since its introduction, and likely within just ten years of use.
Iodine is necessary for thyroid function, and thyroid function is crucial to a plethora of other biological processes.
“We find that for the one quarter of the population most deficient in iodine this intervention raised IQ by approximately one standard deviation,” write the researchers, an affect that translates to 15 I.Q. points. “Our results can explain roughly one decade’s worth of the upward trend in IQ in the U.S. (the Flynn Effect).”
In the absence of iodine, one’s thyroid loses the ability to produce two iodine-containing hormones called T3 and T4. In adults, these thyroid hormones are used to regulate metabolism in the body, but they’re also hugely important in neonatal brain development. If a pregnant mom is iodine deficient, her child can suffer cognitively.
According to I09, in the absence of sources like iodized salt, a person’s iodine intake is dictated largely by her geological location. Seawater, for instance, is rich in iodine, so people in coastal areas are often exposed to the nutrient by eating seaweed, or food grown in iodine-rich soil.