Analysis of food supplements containing iodine: a survey of Italian market

Abstract

Iodine is an essential nutrient for humans as a critical constituent of thyroid hormones; both iodine deficiency and excess have adverse consequences for the thyroid gland. The aims of this research were to compare claimed concentrations of iodine with measured ones in various iodine-supplemented products, estimate the amount of iodine ingested by Italian consumers who use these products, and compare the calculated intakes to the Recommended Daily Allowance and tolerable Upper Level. A convenience sample of 43 food supplements was analyzed for iodine concentration. Analytical values resembled those declared in the label in fewer than half of the examples; in four cases, the maximal daily dose was higher than the tolerable upper level for iodine of 600 microg/day. Labeling of iodine-rich food supplements appears to be unreliable and caution should be exercised in the consumption of food supplements rich in iodine as there is a risk of exceeding the established safe upper level of daily intake.