Bioavailability of iodine from normal diets rich in dairy products resultsof balance studies in women

During the last decade the iodine supply in Germany has increased significa ntly, but there is still a high frequency of goitre. Therefore the question of iodine bioavailability has arisen. In a two-period study 12 women were given a mixed diet of ordinary foods with milk and milk products of differe nt batches. None of the volunteers suffered from an iodine deficiency accor ding to WHO-criteria. Each period ended with a 9-day balance-study protocol in which all foods were provided. Food and fluid intake were registered, a nd urine and faeces were quantitatively collected. The iodine content was d etermined by ICP-MS. The mean intake in the form of solid food amounted to 175 +/- 10 mug I/d and to 27+/-15 mug I/d in fluid form. Milk and dairy pro ducts represented the main source of iodine (37%). Iodine was predominantly excreted in the urine (89%, 171+/-45 mug I/d) and the faeces 11% (20+/-11 mug I/d). The resulting iodine balance was approximately +5%. In one case a n iodine-rich erythrosine preparation with a low iodine bioavailability was used. Between the two periods of consuming different batches of milk and m ilk products no differences were observed concerning the high bioavailabili ty of iodine.