According to Dr. Kelly Lee and colleagues in Nutrition Reviews, "new data indicate a sharp decline in iodine intake in the U.S. during the last 20 years, especially in women of reproductive years."
Iodine deficiency can occur when daily intake falls below 150 mcg per day, the Recommended Daily Allowance (RDA). It is for this reason that healthcare professionals should inform their patients of the potential therapeutic uses of iodine, especially in the prevention and treatment of hypothyroidism.
However, high levels of iodine intake (1,000 to 2,000 mcg per day) temporarily cease production of thyroid hormones. Thus, excessive iodine intake has also been associated with the increased incidence of hypothyroidism.
The U.S. "has a unique set of public health concerns regarding both iodine deficiency, especially in women, which may result in goiter formation, and the effects of too much iodine on certain individuals who are at risk" for certain thyroid conditions. For this reason, it is important that patients and healthcare professionals keep in mind the RDA of dietary iodine.
Nutr Rev 1999;57(6):177-81.