Effect of Reduction in Iodine Content of Edible Salt on the Iodine Status of the Chinese Population.

Objective The aim of this study was to evaluate the impact of the revised Chinese National Standard GB26878-2011 'Iodine Content in Edible Salt' on the iodine status among the Chinese population. Methods In 2011 and 2014, the probability proportionate to size sampling (PPS) was used in each Chinese province to obtain the representative data. In each sampling unit, school children aged 8-10 years and pregnant women were selected. Key indicators included urinary iodine concentration (UIC), thyroid volume (TV), and the iodine content in edible household salt. Results The median urinary iodine concentration (MUIC) decreased between 2011 and 2014 from 238.6 to 197.9 mu g/L in school-age children. The number of provinces with iodine excess decreased to zero. The proportion of children whose UIC was > 300 mu g/L was 18.8% and decreased to 11% compared with 29.8% in 2011. There was no significant difference in UIC < 50 mu g/L between 2014 (4.3%) and 2011 (3.7%) (P > 0.05). The MUIC among pregnant women in 2014 was more concentrated between 110 and 230 mu g/L. The goiter rate among children aged 8-10 years was unchanged, both the goiter rate of 2011 and 2014 remaining below 5%, in view of the sustainable elimination of iodine deficiency disorders. Conclusion The National Standard GB26878-2011 'Iodine Content in Edible Salt' that was introduced in March 2012 resulted in an overall improvement in iodine status, reducing the risk of excessive iodine intake in the Chinese population.