A CENTURY AGO, a lot of northern America was generally known as the goitre belt. In some areas, wherever from 26% to 70% of school-aged kids had the attribute neck swellings, or goitres, attributable to an enlargement of the thyroid gland. After trials confirmed that dietary supplements of iodine might stop goitre, iodised salt was rolled out commercially in 1924, beginning in grocery shops in Michigan. By the Nineteen Forties, the goitre belt had vanished.
