Iodine deficiency is a major unrecognized cause of lowered intelligence
Evidence
For just a few dollars a ton, adding iodine to salt (in the form of potassium iodide) greatly lowered the incidence of deficiency and goiters. But during World War II, when a new crop of Air Force recruits was tested with the Army General Classification Test, scientists noticed a pattern: men from low-iodine areas who showed improved thyroid health also scored substantially higher on the intelligence test. It turns out that iodine deficiency is an unrecognized cause of mental retardation, especially, but not exclusively, in unborn children. — Harriet A. Washington, A Terrible Thing to Waste, 21
Categorization
- corroborated: 825 independent passages support this claim — Harriet A. Washington, A Terrible Thing to Waste, 21
- XREF: connects to: Adding iodine to salt closed a 15-point IQ gap cheaply — Harriet A. Washington, A Terrible Thing to Waste, 18; Toxocara canis infection lowers IQ independent of socioeconomic and racial factors — Harriet A. Washington, A Terrible Thing to Waste, 980; Intelligence develops from environment and experience rather than genetic inheritance (+23 more)