Iodine content in meal replacements in the U.S.
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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.