Iodine Status of Vulnerable Populations in Henan Province of China 2013–2014 After the Implementation of the New Iodized Salt Standard

Abstract

The standard of salt iodine content in China has been adjusted several times since implementation of the universal salt iodization (USI) in 1995. The new standard of iodized salt content was adjusted from 35 ± 15 to 30 ± 9 mg/kg in Henan province in 2012. We aimed to determine whether the vulnerable populations were iodine sufficient after the adjustment of salt iodine content and to provide a guideline for the adjustment of USI policy in China. Two cross-sectional surveys of iodine status in vulnerable populations, including reproductive-age, pregnant and lactating women, infants <2 years, and children aged 8-10 years, were conducted in Henan province in 2013 and 2014. In 2013, the median urinary iodine concentration (mUIC) of reproductive-age women was 200.1 μg/L and that of school children aged 8-10 years was 221.0 μg/L. These mUICs were considered as "more than adequate." The mUICs of reproductive-age women and school children in 2014 showed a significant decline compared to the mUICs in 2013 (P = 0.012 and P = 0.001, respectively). The mUICs of the pregnant women were 204.2 μg/L in 2013 and 202.5 μg/L in 2014, which both met the requirement level recommended by WHO. In 2013, the mUIC of lactating women was 169.1 μg/L and that of infants <2 years was 203.2 μg/L, which were significantly lower than that of 2014 (P < 0.001 and P < 0.001, respectively). The lactating women and infants in 2013 and 2014 were both regarded as "iodine adequate." Iodine status of the vulnerable populations is still adequate as a whole in Henan province after decreasing the salt iodine content. However, the mUIC of school children aged 8-10 years is slightly above the adequate level. To reduce the risk of iodine excess in the general population and prevent the possibility of iodine deficiency of the vulnerable population, it is necessary to explore the appropriate level of iodized salt content.

Iodine deficiency in pregnant women after the adoption of the new provincial standard for salt iodization in Zhejiang Province, China

“…Chen et al and Wang et al observed re-emerging iodine deficiency during pregnancy after the new standard was implemented in Fujian, one of the coastal provinces, where 25 ppm iodine in salt was also adopted [ 32 , 33 ]. A decreased UIC in pregnant women from 224.9 μg/L in 2011 to 202.5 in 2014 was observed in Henan where the provincial standard for salt iodization was decreased to 30 ppm after 2012 [ 34 ]. Similarly, the UIC in school-age children in Henan dropped from 315 μg/L in 2005 to 204 in 2014 [ 34 ].…”

“…A decreased UIC in pregnant women from 224.9 μg/L in 2011 to 202.5 in 2014 was observed in Henan where the provincial standard for salt iodization was decreased to 30 ppm after 2012 [ 34 ]. Similarly, the UIC in school-age children in Henan dropped from 315 μg/L in 2005 to 204 in 2014 [ 34 ]. In addition, we observed that 94.6% of pregnant women consumed iodized salt and 89.9% used adequately iodized salt, which is close to the goals of IDD elimination for coverage rate of iodized salt at the household level (≥95%) and for rate of adequately iodized salt (> 90%) according to the Chinese National Standard of IDD Elimination (GB 16006–2008).…”

An Increase in Consuming Adequately Iodized Salt May Not Be Enough to Rectify Iodine Deficiency in Pregnancy in an Iodine-Sufficient Area of China

“…Chen et al and Wang et al observed that iodine deficiency in the pregnant population occurred after the new standard was implemented while they were previously iodine-sufficient [32,33]. However, Yang et al reported that the sufficient iodine status in pregnant women did not change before and after adopting the new standard [34]. This difference may be explained as follows: (1) Iodine nutrition status in the population is closely related with salt iodine content.…”

Poor Iodine Knowledge, Coastal Region, and Non-Iodized Salt Consumption Linked to Low Urinary Iodine Excretion in Zhejiang Pregnant Women

“…The results showed that the median UIC was 154.6 μg/L [2], indicating that the pregnant population was iodine sufficient at a country level based on the WHO-recommended criterion of the lowest cut-off value for optimal iodine nutrition (150 μg/L) [1]. However, recent surveillance studies have shown that the distribution of iodine nutrition in Chinese pregnant women displays inter- and intra-provincial differences, due to factors such as different geographical residence characteristics [3,4,5] and dietary habits [5]. Pregnant women identified with iodine deficiency were mainly from the coastal provinces of China [2,6].…”