Iodized salt. Because iodine deficiency remains the greatest global cause of mental retardation, buy only iodized salt, and avoid sea salt unless it is infused with iodine, because processing removes its natural iodine. If you adopt a low-salt diet for health reasons, ask your doctor to recommend alternative sources of iodine. Some European salt and Himalayan salt contains fluoride, additional amounts of which should be avoided by pregnant women and very small children. Water in the United States is already fluoridated, and more than fifty studies suggest that additional fluoride may cause an IQ drop in the very young.

Harriet A. Washington, A Terrible Thing to Waste, loc. 446401