Iodine intake is essential for thyroid hormone production. The recommended iodine intake is 150 μg per day for adults. Much of the iodine in the US diet comes from dairy and grain products. However, most product labels do not list iodine content. Meal replacement products are not required to contain specific vitamins and minerals. Nevertheless, meal replacement products can be fortified with 20 or more vitamins and minerals. They are frequently marketed as good and convenient sources of balanced nutrition. Twenty-seven meal replacements from supermarkets in the Boston area were analyzed to measure their levels of iodine in order to determine how meal replacements may contribute to iodine deficiency or excess. Overall mean ± SD iodine content was 49.7 ± 125.4 μg/serving. However, one meal replacement had 671.9 μg iodine per serving; once this outlier was excluded the mean ± SD was 25.8 ± 16.9 μg iodine serving. The meal replacements were compared by form (liquid, bar, and powder) and by type (vegan and non-vegan). The mean iodine content differed between the forms (liquid, bar, powder) and was highest for the liquids (mean ± SD: 37.4 ± 6.5 μg/serving; p-value 0.02, excluding outliers). The non-vegan meal replacements had a higher mean iodine content compared to the vegan meal replacements (mean ± SD: 31.6 ± 15.78 μg/serving; p-value 0.01, excluding outliers). All of the meal replacements contained detectible amounts of iodine regardless of whether it was listed on their labels (41% did not list iodine). Overall the meal replacements in this study were found to be good sources of iodine. However, consumers should be aware that packaging labels may not accurately reflect the amount of iodine present. One meal replacement was a potential source of excess iodine intake.

No description available.

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Iodine is a biophilic element with one natural long-lived isotope, 129I (t1/2= 15.6 million years), and one stable isotope, 127I. The inventory of 129I in surface environments has been overwhelmed by anthropogenic releases over the past 50 years. The objective of this study is to utilize the elevated concentration and biophilic nature of 129I and the isotopic ratio of iodine (129I/127I) as a tracer of water mass movement and organic matter. Additionally, the significantly elevated values of 129I/127I could provide a geochronometer, similar to the way 14C is used, particularly for terrestrial organic matter that is less than 50 years old. A series of laboratory experiments and field investigations were carried out to characterize the dominant chemical forms of dissolved iodine, i.e., iodide (I-), iodate (IO 3-), and organic iodine (DOI) in natural waters. Sensitive methods were developed for the analysis of nanomolar quantities of 127I species in a variety of environmental systems using high performance liquid chromatography (HPLC) and an organic iodine decomposition technique, dehydrohalogenation. The potential use of 129I/127I as a hydrological tracer was evaluated through measurements of 129I and 127I, which were carried out in wells in the artificially recharged ground water basin of Orange County, California. Literature values of aquifer ages based on 3H/3He and δ18O tracer data, as well as time-series data of chloride and Santa Ana River flow rates over the past decade were compared to values for 129I and 127I. The iodine isotopes demonstrated a conservative behavior in these aquifers, suggesting that the observed variations of these isotopes reflect past river flow conditions during the time of recharge. The feasibility of using 129I/127I ratios to trace terrestrial organic matter across an estuary was tested. A novel analytical technique to determine 129I/127I ratios in DOI was developed for this investigation. The results of a Galveston Bay transect clearly show that 129I/127I ratios in DOI can remain elevated up to salinity of about 15, but that 129I/127I values of inorganic iodine species do not show any trend with change in salinity gradient due to fast isotopic and chemical equilibration in the estuarine waters.

Iodine is a biophilic element with one natural long-lived isotope, 129I (t1/2= 15.6 million years), and one stable isotope, 127I. The inventory of 129I in surface environments has been overwhelmed by anthropogenic releases over the past 50 years. The objective of this study is to utilize the elevated concentration and biophilic nature of 129I and the isotopic ratio of iodine (129I/127I) as a tracer of water mass movement and organic matter. Additionally, the significantly elevated values of 129I/127I could provide a geochronometer, similar to the way 14C is used, particularly for terrestrial organic matter that is less than 50 years old. A series of laboratory experiments and field investigations were carried out to characterize the dominant chemical forms of dissolved iodine, i.e., iodide (I-), iodate (IO 3-), and organic iodine (DOI) in natural waters. Sensitive methods were developed for the analysis of nanomolar quantities of 127I species in a variety of environmental systems using high performance liquid chromatography (HPLC) and an organic iodine decomposition technique, dehydrohalogenation. The potential use of 129I/127I as a hydrological tracer was evaluated through measurements of 129I and 127I, which were carried out in wells in the artificially recharged ground water basin of Orange County, California. Literature values of aquifer ages based on 3H/3He and δ18O tracer data, as well as time-series data of chloride and Santa Ana River flow rates over the past decade were compared to values for 129I and 127I. The iodine isotopes demonstrated a conservative behavior in these aquifers, suggesting that the observed variations of these isotopes reflect past river flow conditions during the time of recharge. The feasibility of using 129I/127I ratios to trace terrestrial organic matter across an estuary was tested. A novel analytical technique to determine 129I/127I ratios in DOI was developed for this investigation. The results of a Galveston Bay transect clearly show that 129I/127I ratios in DOI can remain elevated up to salinity of about 15, but that 129I/127I values of inorganic iodine species do not show any trend with change in salinity gradient due to fast isotopic and chemical equilibration in the estuarine waters.

Echinoids (sea urchins and sand dollars) undergo thyroid hormone (TH) regulated larval development and several species can endogenously synthesize these hormones. Although iodine is the essential component for TH synthesis, nothing is known about iodine uptake mechanisms in echinoids. This thesis primarily aimed to characterize integumental iodine uptake in larvae (echinoplutei) of the purple sea urchin Strongylocentrotus purpuratus. The two mechanisms considered were: iodine uptake via sodium dependent transport utilizing orthologs of vertebrate sodium iodide symporter (NIS) and apical iodide transporter (AIT) versus hydrogen peroxide dependent diffusion (PDD) of iodine. Pharmacology and radioiodine (125I) experiments characterized the effects of various compounds on echinoid iodine uptake. The results demonstrate that purple sea urchin echinoplutei acquire iodine from feeding on microalgae and through integumental transfer. Integumental transfer of iodine is inhibited by cyanide and is temperature dependent. Echinoplutei are not affected by perchlorate exposure demonstrating that NIS/AIT is not involved in S. purpuratus iodine uptake. NIS and AIT are both members of the Sodium Solute Carrier 5 (SSF5) transporter family and phylogenetic analysis of various vertebrate and invertebrate SLC5 members (obtained through BLAST searches) indicated that NIS-like transporters might be a vertebrate synapomorphy. Hydrogen peroxide exposure and oxidative stress induced an increase in iodine influx, whereas reducing agents and peroxidase inhibitors disrupted iodine uptake supporting a PDD-based iodine uptake model. In situ hybridization, immunohistochemistry and real time-PCR analysis demonstrate that the sea urchin dual oxidase 1 (Udx1) (an NADPH oxidase that produced hydrogen peroxide) is expressed throughout all stages of larval development in both S. purpuratus and Lytechinus variegatus specifically occurring in epithelial cells. These findings are the first data to demonstrate Udx1 presence and potential activity outside of fertilization and embryogenesis in echinoplutei. The expression patterns and pharmacological results make Udx1 an attractive candidate for involvement in integumental iodine transfer through PDD. These data provide the first evidence for PDD in an animal. The results also suggest that NIS/AIT may be a vertebrate synapomorphy and PDD of iodine across the integument may be widespread across organisms. Future characterization of iodine uptake mechanism in diverse taxa will address this issue. / Studies were funded by the Natural Sciences and Engineering REsearch Council (NSERC) to A.H. [grant number 400230], Equipment purchased with funding from the Caiadian Foundation for Innovation CFI and NSERC [grant number 400587] to A.H.

Thesis (doctoral)--Universität Zürich, 1956.

Thesis (doctoral)--Universität Zürich, 1956.