Re-exploration of dietary iodine intake in Chinese adult males using a modified iodine balance study

There is still controversy about optimal dietary iodine intake as the Universal Salt Iodization policy enforcement in China. A modified iodine balance study was thus conducted to explore the suitable iodine intake in Chinese adult males using the iodine overflow hypothesis. In this study, thirty-eight apparently healthy males (19 center dot 1 (sd 0 center dot 6) years) were recruited and provided with designed diets. After the 14-d iodine depletion, daily iodine intake gradually increased in the 30-d iodine supplementation, consisting of six stages and each of 5 d. All foods and excreta (urine, faeces) were collected to examine daily iodine intake, iodine excretion and the changes of iodine increment in relation to those values at stage 1. The dose-response associations of iodine intake increment with excretion increment were fitted by the mixed effects models, as well as with retention increment. Daily iodine intake and excretion were 16 center dot 3 and 54 center dot 3 mu g/d at stage 1, and iodine intake increment increased from 11 center dot 2 mu g/d at stage 2 to 118 center dot 0 mu g/d at stage 6, while excretion increment elevated from 21 center dot 5 to 95 center dot 0 mu g/d. A zero iodine balance was dynamically achieved as 48 center dot 0 mu g/d of iodine intake. The estimated average requirement and recommended nutrient intake were severally 48 center dot 0 and 67 center dot 2 mu g/d, which could be corresponded to a daily iodine intake of 0 center dot 74 and 1 center dot 04 mu g/kg per d. The results of our study indicate that roughly half of current iodine intakes recommendation could be enough in Chinese adult males, which would be beneficial for the revision of dietary reference intakes.