Salt iodization beginning in 1924 raised IQ by approximately one standard deviation (15 points) for the quarter of the population most deficient in iodine.

Evidence

The Cognitive Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States (Journal of the European Economic Association)

Categorization

• corroborated: 3 independent passages support this claim
• XREF: connects to: Adding iodine to salt closed a 15-point IQ gap cheaply — Harriet A. Washington, A Terrible Thing to Waste, 18; Results are consistent with iodization raising IQ by 15 points in iodine-deficient areas and a nationwide average increase of ~3.5 IQ points. — The Cognitive Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States; We find that for the one quarter of the population most deficient in iodine this intervention raised IQ by approximately one standard deviation. — The Cognitive Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States (+23 more)

Related

• We find that for the one quarter of the population most deficient in iodine this intervention raised IQ by approximately one standard deviation. (similarity 0.98)
• Introduction of iodized salt increased IQ by approximately 15 points for those most deficient in iodine. (similarity 0.98)
• Results are consistent with iodization raising IQ by 15 points in iodine-deficient areas and a nationwide average increase of ~3.5 IQ points. (similarity 0.96)
• A 2017 study found that the introduction of iodized salt in 1924 raised IQ for the one-quarter of the population most deficient in iodine. (similarity 0.95)
• Salt iodization raised IQ scores of millions of people by 15 IQ points in iodine-deficient regions and is highly cost-effective at pennies per person per year. (similarity 0.95)
• Americans gained up to 15 IQ points after iodized salt became mandatory in 1924. (similarity 0.95)
• A 2013 study found a gradual increase in average intelligence of 1 standard deviation, 15 points in iodine-deficient areas and 3.5 points nationally after the introduction of iodised salt. (similarity 0.94)
• Adding iodine to salt beginning in 1924 increased IQ in America by as much as 15 points and boosted the U.S. economy. (similarity 0.94)
• The lower range of estimates is consistent with iodization raising IQ by 15 points, but also documents at least 10,000 excess deaths from iodine-induced hyperthyroidism. (similarity 0.93)
• Iodized salt raised IQs by a full standard deviation (15 points) in iodine-deficient areas, and may explain a decade’s worth of the Flynn effect. (similarity 0.92)
• Iodine played a substantial role in cognitive improvements across the American population in the 20th century. (similarity 0.92)
• Men from the lowest-iodine areas born in 1924 or later had an average IQ that was 15 points higher than their predecessors. (similarity 0.91)
• For the quarter of the population most deficient in iodine, salt iodization raised IQ by approximately one standard deviation, explaining roughly a decade’s worth of the Flynn Effect. (similarity 0.90)
• In low-iodine counties, the probability of assignment to the Air Forces rose significantly after the introduction of iodized salt. (similarity 0.90)
• Morton Salt began nationwide iodized salt distribution in 1924; access to iodine, a key determinant of cognitive ability, rose sharply. (similarity 0.90)