Government experts, once concerned that Americans might be consuming too much iodine, now warn that iodine deficiencyâ€"a serious health threat in developing nationsâ€"could resurface in this country.

Researchers suggest several reasons for the overall drop in iodine levels first observed in the late ’90s:

• People who cut back on salt to control hypertension could also be inadvertently reducing their iodine levels. Iodized salt is rarely found in packaged foods, and most salt substitutes are not fortified with the important mineral.

• More meals are being eaten outside the home. Restaurants usually order salt in bulk, and it’s often the plain version.

• Companies now use iodine-free disinfectants to clean food-processing equipment. In the past, iodine-based solutions added iodine to meat, dairy, and grain products.

Iodine supports fetal and infant brain development and is critical to thyroid function in adults. The normal daily requirement for adults is 150 mcg per day; pregnant women need more to prevent cretinism, a form of physical and mental retardation, in their babies. Inadequate iodine intake can cause population-wide drops in IQ in areas where deficiency is common.

Two servings of fish each week provide healthy amounts of iodine (as well as beneficial omega-3 fatty acids). People on salt-restricted diets might also consider taking a multivitamin that contains iodine.