Is the current iodine content in edible salt appropriate for eliminating iodine deficiency in China.

OBJECTIVE This study was designed to measure the urinary iodine excretion of volunteers who daily consumed iodized salt and to evaluate whether the current iodine content in salt is appropriate. A field trial study was then conducted to determine how the salt iodization content should be adjusted, either to prevent iodine deficiency or to avoid excess consumption. METHODS A total of 1,099 volunteers from 399 households from urban and rural regions were selected. The levels of salt iodine and urinary iodine were measured prior to the field trial. All the households were randomly divided into four groups according to different salt iodine concentrations: group A, 6+/-2 mg/kg; group B, 15+/-2 mg/kg, group C, 24+/-2 mg/kg; and group D, 34+/-2 mg/kg. The urinary iodine levels of households were determined over five consecutive days, starting on the 27th day after the intervention. RESULTS Before the intervention, the median urinary iodine excretions for urban and rural residents are 294 microg/L and 509 microg/L, respectively. By contrast, urinary iodine excretion in all groups significantly declined after the intervention. The median excretions of urinary iodine on the 28th day after the intervention for all groups were 97.2 microg/L, 199 microg/L, 249 microg/L and 331 microg/L for urban residents, and 101 microg/L, 193 microg/L, 246 microg/L and 308 microg/L for their rural counterparts, respectively. CONCLUSIONS The trial exhibits a tendency of slightly excessive iodine intake among the households under the currently recommended standard.