Longitudinal study of iodine in market milk and infant formula via epiboron neutron activation analysis

Abstract

Iodine is an essential nutrient in the human diet. Its primary role is expressed as a component of thyroxine (T4) and the corresponding deiodinated triiodothyronine (T3) hormones produced by the thyroid as part of the system that regulates growth, mental development and metabolism. The recommended daily allowance (RDA) for iodine ranges from 50 μg/day for infants to 150 μg/day for adults. Reports over the last 15 years have indicated that the U.S. diet provides 2 to 7 times the iodine RDA and that dairy products typically provide 20 to 60 percent of the dietary iodine intake. Measurements of iodine in dietary components and composites reported in FDA studies have been done calorimetrically. These studies have, according to the authors, both under reports (by up to −50%) and over reports (by up to +80%) the iodine, depending on food type, compared to a radiochemical NAA reference method. Milk is typically under reported by −20%. The objective of this study was to utilize epiboron neutron activation analysis (EBNAA) to study the iodine concentrations, and seasonal variations of iodine, and market milk and infant formula, collected 15 years apart, in comparison with the Food and Drug Administration (FDA) market-basket reports.