Iodine and iodized salt in the U.S.
Rather than try to make too much out of a recent study in Thyroid that found significant correlations of iodine intakes with consumption of yogurt and saltwater fish, but no relationship with use of iodized salt, we'll adopt the skepticism of the study's authors, Angela M. Leung et al, who explain their research design "may not have been sufficiently comprehensive" and "further studies are warranted to determine important sources of dietary iodine in the United States."
The study used food consumption questionnaires for 46 Boston, MA-area volunteers (91% middle-aged women). Among the findings, while 89% regularly purchase salt for home use, only 56% considered using iodized salt important; only 24% reported using iodized salt during the previous day (the same percentage used a multivitamin, half of which had the recommended 150 micrograms of iodine. Eighty percent purchased based on brand and 87% based on packaging.
The article provided some valuable reminders about the importance of adequate iodine nutrition:
Globally, iodine deficiency is one of the four major nutritional deficiency disorders and is the single most common cause of preventable mental retardation and brain damage. About 2.2 billion people (38% of the world's population) live in iodine-deficient areas. Although iodine supplementation has virtaully eliminated endemic goiter in the United States, NHANES assessments over the past 30 years have suggested that dietary iodine intake has decreased, especially among women of childbearing age. Adequate maternal iodien is crucial for normal thyroid function in the developing fetus, which in turn is essential for normal neuro-cognitive development both in utero and in infancy.
Whatever the source, these study participants, mostly women in their childbearing years, consumed less than the recommended amounts of iodine (~140 micrograms/day). We need to pay attention.
