Iron Is Well Absorbed by Healthy Adults after Ingestion of Double-Fortified (Iron and Dextran-Coated Iodine) Table Salt and Urinary Iodine Excretion Is Unaffected

Manuscript received 14 April 1998. Initial reviews completed 7 July 1998. Revision accepted 6 October 1998.

Departments of Paediatrics and of Nutritional Sciences, University of Toronto and Division of Gastroenterology/Nutrition and the Research Institute Hospital For Sick Children, Toronto, Ontario, Canada M5G 1X8

Severe deficiencies of iron (Fe) and iodine (I) affect more than one third of the world's population. A table salt, fortified with I and Fe, would be useful in areas in which anemia and goiter coexist. However, interactions between the two minerals have prevented their simultaneous use as fortificants. A method has been developed to coat I with dextran such that after spraying onto table salt, Fe and I do not interact. Our objective was to determine the absorption of Fe and the urinary excretion of I from table salt when provided in meals designed to significantly inhibit or enhance Fe absorption. Subjects (n = 16) ingested Fe-enhancing and Fe-inhibiting meals containing 5 g of table salt with 0.39 µmol dextran-coated I as potassium iodide and 1 mg of Fe (ferrous fumarate labeled with ⁵⁹Fe) per gram of salt. Subjects also received a reference dose of 3 mg of ferrous fumarate labeled with ⁵⁹Fe to "correct" for interindividual variation in iron absorption at a later date. Measured by whole-body counting, Fe-absorption from the Fe-enhancing meal (36.2 ± 12.0%, corrected; 13.5 ± 13.8% uncorrected) was significantly higher than that from the Fe-inhibiting meal (7.4 ± 11.3%, corrected; 4.0 ± 8.4%, uncorrected) (P < 0.0001). Urinary excretion of iodine at baseline and postingestion were not significantly different (0.89 ± 0.5 vs. 1.06 ± 0.39 µmol/L, P < 0.47) and were within the normal range. We conclude that Fe was well absorbed but influenced by the composition of the meal and that urinary excretion of iodine was maintained in the normal range with dextran-coated iodine.

The Journal of Nutrition Vol. 129 No. 1 January 1999, pp. 117-121
Copyright ©1999 by the American Society for Nutritional Sciences

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